U.S. Department of the Interior

U.S. Geological Survey

Prepared by the U.S. Geological Survey Office of Water Quality, National Water Quality Laboratory

Determination of Semivolatile Organic Compounds and 

Polycyclic Aromatic Hydrocarbons in Solids by Gas 

Chromatography/Mass Spectrometry

Techniques and Methods 5–B3
Determination of Semivolatile Organic 

Compounds and Polycyclic Aromatic 

Hydrocarbons in Solids by Gas 

Chromatography/Mass Spectrometry

By Steven D. Zaugg, Mark R. Burkhardt, Teresa L. Burbank, Mary C. Olson, 

Jana L. Iverson, and Michael P. Schroeder

Techniques and Methods 5–B3

U.S. Department of the Interior

U.S. Geological Survey

Chapter 3

Section B, Methods of the National Water Quality Laboratory

Book 5, Laboratory Analysis
U.S. Department of the Interior

Dirk Kempthorne, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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Suggested citation:

Zaugg, S.D., Burkhardt, M.R., Burbank, T.L., Olson, M.C., Iverson, J.L., and Schroeder, M.P., 2006, Determination of 

semivolatile organic compounds and polycyclic aromatic hydrocarbons in solids by gas chromatography/mass spectrometry: U.S. Geological Survey Techniques and Methods, book 5, chap. B3, 44 p.
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope .......................................................................................................................................3

Analytical Method..........................................................................................................................................4

1. Scope and Application ..............................................................................................................4

2. Summary of Method...................................................................................................................5

3. Safety Precautions and Waste Disposal................................................................................5

4. Interferences...............................................................................................................................5

5. Apparatus and Equipment.........................................................................................................5

6. Reagents and Consumable Materials.....................................................................................6

7. Sample Preparation Procedure ...............................................................................................8

8. Instrumental Analysis ..............................................................................................................12

9. Calculation and Reporting of Results....................................................................................17

10. Quality Assurance and Quality Control.................................................................................18

11. Results and Discussion of Method Validation.....................................................................19

Summary and Conclusions.........................................................................................................................40

References Cited..........................................................................................................................................42

Glossary.........................................................................................................................................................44

Figures

1–2. Photographs showing:

 1. Solid-phase extraction assembly for accelerated solvent extracts for use in

determining semivolatile organic compounds and polycyclic aromatic 

hydrocarbons. ......................................................................................................................11

 2. Solid-phase elution module assembly used in the analytical method for determining semivolatile organic compounds and polycyclic aromatic 

hydrocarbons. ......................................................................................................................12

3. Graph showing least squares regression plots for concentrations of naphthalene

(A) and benzo[a]pyrene (B) determined in 28 sediment samples by accelerated

solvent extraction (ASE) and by Soxhlet extraction. ............................................................40

4. Boxplot showing results for analysis of 28 environmental soil and sediment 

samples. .......................................................................................................................................41

Tables

1. Semivolatile and polycyclic aromatic hydrocarbon compounds determined using

this method. ...................................................................................................................................3

2. Alkylated polycyclic aromatic hydrocarbon homolog groups determined using this

method and reported with estimated concentrations............................................................4

3. An example of an accelerated solvent extraction (ASE) schedule for 13 cells.................9
iv

4. An example of an accelerated solvent extraction (ASE) method for a 120°C 

extraction. ....................................................................................................................................10

5. Retention times, relative retention times, gas chromatography/mass spectrometry

quantitation ions, confirmation ions, and percent relative abundance of

confirmation ions for individual method compounds and alkylated polycyclic

aromatic hydrocarbon homolog groups. ................................................................................13

6. Gas chromatography/mass spectrometry analytical sequence suggested for use

with this method..........................................................................................................................16

7. Compounds with relative response factors used for the quantitation of alkylated

polycyclic aromatic hydrocarbon homolog groups. .............................................................18

8. Semivolatile and polycyclic aromatic hydrocarbon compounds detected in

unfortified reagent-sand, stream-sediment, and topsoil samples. ....................................20

9. Polycyclic aromatic hydocarbon and semivolatile compound mean bias and

precision of spike recovery data for nine replicates with compounds spiked at 

15 micrograms per sample in reagent-sand, stream-sediment, and topsoil 

samples. .......................................................................................................................................21

10. Polycyclic aromatic hydrocarbons and semivolatile compound mean bias and

precision of spike recovery data for nine replicates with compounds spiked at 

1.5 micrograms per sample in reagent-sand, stream-sediment, and topsoil 

samples. .......................................................................................................................................22

11. Mean bias and precision of spike recovery data for nine replicates with

compounds spiked at 1.5 and 15 micrograms per sample in reagent-sand,

stream-sediment, and topsoil samples for compounds that are not included in this

method..........................................................................................................................................24

12. Initial method detection limits calculated from the precision data reported in table

10 for the nine replicate reagent-sand samples spiked at 60 micrograms per

kilogram per compound.............................................................................................................25

13. Concentrations certified by the National Institute of Standards and Technology for

Standard Reference Material 1944 determined by Soxhlet extraction and this

method..........................................................................................................................................27

14. Concentrations of alkylated homolog groups detected in Standard Reference

Material 1944 determined by Soxhlet extraction and this method, but not reported

by the National Institute of Standards and Technology. ......................................................28

15. Replicate environmental sample results, in micrograms per kilogram, using

accelerated solvent extraction. ...............................................................................................29

16. Mean average deviation and range of average deviations for compounds detected

in nine duplicate sediment samples and one triplicate sample extracted using

accelerated solvent extraction. ...............................................................................................32

17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per

kilogram, for 28 sediment samples. .........................................................................................33

18. Correlation of Soxhlet and accelerated solvent extraction results for 28 sediment

samples. .......................................................................................................................................39

Tables—Continued
Conversion Factors

Multiply By To obtain

centimeter (cm) 3.94 x 10-1 inch

gram (gm) 3.53 x 10-2 ounce, avoirdupois

kilogram (kg) 3.53 x 101 ounce, avoirdupois

kilopascal (kPa) 1.45 x 10-1 pounds per square inch

liter (L) 3.38 x 101 ounce, fluid

meter (m) 3.281 foot

microgram (μg) 3.53 x 10-8 ounce, avoirdupois

microliter (μL) 3.38 x 10-5 ounce, fluid

micrometer (μm) 3.94 x 10-5 inch

milligram (mg) 3.53 x 10-5 ounce, avoirdupois

milliliter 3.38 x 10-2 ounce, fluid

millimeter (mm) 3.94 x 10-2 inch

nanogram (ng) 3.53 x 10-11 ounce, avoirdupois

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F=(1.8×°C)+32

Abbreviated water-quality units used in this report

% percent

°C degree Celsius

°C/min degree Celsius per minute

μg/kg microgram per kilogram (parts per billion)

μg/mL microgram per milliliter

mL/min milliliter per minute

ng/μL nanogram per microliter

amu atomic mass unit

AD average deviation

ASE accelerated solvent extraction

ASMB Alberta Sweet Mix Blend

BHT butylated hydroxy toluene

CAS Chemical Abstracts Service

CASRN Chemical Abstracts Service registry number

CCV continuing calibration verification solution

DCM dichloromethane

DEE diethyl ether

DFTPP decafluorotriphenylphosphine

E estimated remark code

EI electron impact

dPAHIS perdeuterated polycyclic aromatic hydrocarbon internal standard

eV electron volts

FS full-scan ion monitoring

GC gas chromatography (or gas chromatograph)
vi

GC/MS gas chromatography/mass spectrometry

ID identification number

IDL instrument detection limit

IPA isopropyl alcohol

IS internal standard

Lab ID laboratory identification number

LRB laboratory reagent blank

LRS laboratory reagent spike

LT–MDL long-term method detection level

MDL method detection limit

MRL minimum reporting level

MS mass spectrometry (or mass spectrometer)

m/z mass-to-charge ratio

n number of samples

NAWQA National Water-Quality Assessment Program

N-evap nitrogen gas evaporator

NIST National Institute of Standards and Technology

ND not determined

nd not detected

no. number

NPE number of points excluded

NR not reported

NWIS National Water Information System

NWQL National Water Quality Laboratory

OC organic carbon

PAH polycyclic aromatic hydrocarbon

PLE pressurized liquid extraction

PLEHW pressurized liquid extraction with subcritical heated water

QA/QC quality assurance/quality control

QA quality assurance

QC quality control

r 2 correlation coefficient

RR retention reference

RRF relative response factor

RRT relative retention time

RSD relative standard deviation

RT retention time

sed sediment

SOX Soxhlet

SPE solid-phase extraction

SRM Standard Reference Material 

TPC third-party check solution

Abbreviated water-quality units used in this report—

Continued
vii

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

± plus or minus

< less than

v/v volume-to-volume ratio

Abbreviated water-quality units used in this report—

Continued

Determination of Semivolatile Organic Compounds and 

Polycyclic Aromatic Hydrocarbons in Solids by Gas 

Chromatography/Mass Spectrometry

By Steven D. Zaugg, Mark R. Burkhardt, Teresa L. Burbank, Mary C. Olson, Jana L. Iverson, and 

Michael P. Schroeder

Abstract

A method for the determination of 38 polycyclic aromatic 

hydrocarbons (PAHs) and semivolatile organic compounds in 

solid samples is described. Samples are extracted using a pressurized solvent extraction system. The compounds of interest 

are extracted from the solid sample twice at 13,800 kilopascals; first at 120 degrees Celsius using a water/isopropyl 

alcohol mixture (50:50, volume-to-volume ratio), and then the 

sample is extracted at 200 degrees Celsius using a water/isopropyl alcohol mixture (80:20, volume-to-volume ratio). The 

compounds are isolated using disposable solid-phase extraction (SPE) cartridges containing divinylbenzene-vinylpyrrolidone copolymer resin. The cartridges are dried with nitrogen 

gas, and then sorbed compounds are eluted from the SPE 

material using a dichloromethane/diethyl ether mixture (80:20, 

volume-to-volume ratio) and through a sodium sulfate/Florisil 

SPE cartridge to remove residual water and to further clean up 

the extract. The concentrated extract is solvent exchanged into 

ethyl acetate and the solvent volume reduced to 0.5 milliliter. 

Internal standard compounds are added prior to analysis by 

capillary-column gas chromatography/mass spectrometry.

Comparisons of PAH data for 28 sediment samples 

extracted by Soxhlet and the accelerated solvent extraction (ASE) method described in this report produced similar 

results. Extraction of PAH compounds from standard reference material using this method also compared favorably 

with Soxhlet extraction. The recoveries of PAHs less than 

molecular weight 202 (pyrene or fluoranthene) are higher by 

up to 20 percent using this ASE method, whereas the recoveries of PAHs greater than or equal to molecular weight 202 are 

equivalent.

This ASE method of sample extraction of solids has 

advantages over conventional Soxhlet extraction by increasing 

automation of the extraction process, reducing extraction time, 

and using less solvent. Extract cleanup also is greatly simplified because SPE replaces commonly used gel permeation 

chromatography.

The performance of the method (as expressed by mean 

recoveries and mean precision) was determined using Ottawa 

sand, a commercially available topsoil, and an environmental stream sediment, fortified at 1.5 and 15 micrograms per 

compound. Recoveries of PAH and semivolatile compounds 

in Ottawa sand samples fortified at 1.5 micrograms averaged 

88 percent ± 9.4 percent relative standard deviation, and calculated initial method detection limits per compound averaged 

14 micrograms per kilogram, assuming a 25-gram sample size. 

The recovery for 1,2,4-trichlorobenzene is less than 60 percent; thus, the concentration of this compound will always be 

reported as estimated with the “E” remark code.

The analysis of 25 alkylated PAH homolog groups also 

can be determined with this method with extra data analysis and review, but because of the lack of authentic reference standard compounds, these results are considered to be 

semiquantitative. The PAH homolog groups are quantitated 

using the response factor of a parent PAH method compound, 

if available. Precision data for the alkylated PAH homologs 

detected in a marine sediment standard reference material 

(SRM 1944) also are presented to document and demonstrate 

method capability.

Introduction

Pressurized liquid extraction (PLE) of solid samples 

offers advantages for automated sample preparation and 

reduced extraction time, and it uses less solvent compared 

to conventional Soxhlet extraction. Recently, Hawthorne, 

Trembley, and others (2000) used PLE with subcritical heated 

water (PLEHW) at moderate temperatures (about 100oC) 

for extracting polar to moderately polar organic compounds 

from sediments. The solubility of solutes in subcritical water 

increases dramatically (about a threefold increase with every 

25oC increase), which is largely a function of the decreasing 

dielectric constant of water (Hawthorne, Trembley, and others, 

2000). Using PLEHW above 250oC, they demonstrated that 

the extraction of nonpolar high molecular weight compounds, 

such as polycyclic aromatic hydrocarbons (PAHs) from environmental solids, is feasible.
Currently (2006), PLEHW above 250oC has been performed using home-made instruments because of the lack of 

commercially available options. The ASETM 200 is a commercially available PLE instrument produced by Dionex (Sunnyvale, Calif., USA), and the process, which also has been 

termed “accelerated solvent extraction” (ASE), generally uses 

conventional organic solvents at about 100oC. The ASETM 200 

has an upper operating limit of 200oC, which is too low to 

effectively extract nonpolar high molecular weight organic 

compounds, such as PAHs having molecular weights of 202 or 

higher, using only subcritical water. However, the addition of 

an organic cosolvent generally has a similar effect on increasing compound solubility as increasing temperature (Curren 

and King, 2001). Thus, a cosolvent is required to effectively 

extract high molecular weight PAH compounds. Even though 

temperature and cosolvents greatly affect solubility, pressure 

has little effect on solubility (U.S. Environmental Protection 

Agency, 2000) but must be high enough to maintain water 

in the liquid state. However, the elevated ASETM 200 system 

pressure substantially increases solvent permeation into the 

sediment matrix and thereby greatly improves extraction 

efficiency.

The PLEHW of sediments provides more selectivity for 

analytes than conventional Soxhlet extraction using organic 

solvents as supported by a dramatic reduction in the extraction 

of the bulk organic nonpolar matrix and noticeable improvement in the quality of the extract (Hawthorne, Grabanski, and 

others, 2000). It is possible to gain some degree of selectivity 

using solvent modified PLEHW by varying the modifier concentration. However, the use of cosolvents produces somewhat 

dirtier extracts than if pure water could be used, and generally 

requires cleanup steps prior to analysis. In a production laboratory, extract quality (low matrix background) is desirable to 

facilitate a reproducible instrument response and minimize gas 

chromatography/mass spectrometry (GC/MS) maintenance.

Environmental sediment samples generally require 

extensive extract clean-up steps to provide a low matrix background amenable to analysis and yet retain the compounds 

of interest. Even though ASE extracts are noticeably cleaner 

than methylene chloride Soxhlet extracts, it is still advantageous to perform additional extract cleanup. Coupling PLE 

and SPE allows for complex matrices to be extracted, matrix 

interferences minimized, and full-scan GC/MS analysis to be 

performed.

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic compounds composed of two or more fused conjugated 

benzene rings that often have attached alkyl substituent(s), 

referred to as alkylated PAHs. These compounds commonly 

are associated with fossil fuels or combustion of fossil fuels. 

There are many possible environmental sources for PAHs 

(Walker and others, 2005) and many are considered to be toxic 

and carcinogenic (Nauss, 1995), thus indicating that long-term 

exposure poses a risk to aquatic and terrestrial organisms. The 

natural processes and combustion of fossil fuels that form 

alkylated PAHs normally can favor specific homolog groups 

according to the predominant conditions. The analysis of 

alkylated PAH homolog groups often can help deduce possible 

mechanisms or conditions required for their formation.

Alkylated PAHs are categorized by the total number of 

alkyl carbon atoms present, so that a particular homolog group 

includes all the isomers with the same number of carbon atoms 

in the substituents attached to the parent PAH. Thus, various combinations of parent PAHs and alkyl substituents can 

occur. For example, the possible substitutions for a C3-PAH 

could include propyl- (n-propyl-, isopropyl-), trimethyl-, or 

ethylmethyl. Alkylated PAH homolog series from C1 through 

C5 substituent(s) having the same parent PAH are of particular 

interest. For example, an alkylated PAH homolog series for 

naphthalene follows: C1-alkylated naphthalene, C2-alkylated 

naphthalene, and so forth up to C5-alkylated naphthalene.

If the parent PAH also is an isomer of another parent PAH, their homolog groups are combined for reporting 

purposes. The parent PAH compounds phenanthrene/anthracene, fluoranthene/pyrene, benz[a]anthracene/chrysene, and 

benzo[a]pyrene/perylene are isomers, so their alkyl homolog 

groups are combined and reported together, for example, as 

C3-alkylated phenanthrene/anthracene.

Isomers within a homolog group have common physical 

properties, such as the same molecular weight and fragmentation patterns in a mass spectrometer. The fragment ions 

produced for each isomer within the same homolog group 

typically are identical, although the abundance ratios can be 

different. This results in a complex chromatographic pattern of 

partially resolved isomers. The total response of the isomers 

for a particular alkyl substituted PAH group is summed to 

calculate the relative response factor (RRF) from the calibration curve of a related method compound. The RRF, although 

from a related compound, may or may not reflect each 

individual isomer’s response. Wang and others (1994) found 

that by using the RRF produced from the parent naphthalene 

standard’s calibration curve, a quantitation error of 30 to 

150 percent was typical for alkylated naphthalene homolog 

groups. For this reason, and because authentic standards are 

not available for every alkylated PAH isomer, the total concentration of each homolog group is reported by the NWQL 

as estimated as indicated by an “E” remark code. Reference 

standard compounds for the alkylated PAH homolog groups 

are not routinely available, and thus, they are set apart from 

the method compounds, whose concentrations are calculated 

using authentic reference standards.

The U.S. Geological Survey (USGS) National Water 

Quality Labotatory (NWQL) developed a method to determine 

38 semivolatile organic compounds and polycyclic aromatic 

hydrocarbons (table 1) and 25 alkylated PAH homolog groups 

(table 2) in solids. The alkylated PAH homologs are qualitatively identified and semiquantitated using the response 

factor and calibration curve from a closely related reference 

compound within its homolog series or the appropriate parent 

PAH. Reference mass spectral agreement and isotopic patterns 

are used to qualitatively identify the alkylated PAH homolog 

groups, which then can be reported semiquantitatively as the 

 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Table 1. Semivolatile and polycyclic aromatic hydrocarbon compounds determined using this method (schedule 5506).

[NWIS, National Water Information System; CAS, Chemical Abstracts Service Registry Number]

Compound name

NWIS 

parameter 

code

CAS

number1

Acenaphthene 64108 83-32-9

Acenaphthylene 64109 208-96-8

Anthracene 63180 120-12-7

Anthraquinone 63181 84-65-1

Benz[a]anthracene 63610 56-55-3

Benzo[b]fluoranthene 64111 205-99-2

Benzo[k]fluoranthene 64114 207-08-9

Benzo[g,h,i]perylene 64113 191-24-2

Benzo[a]pyrene 63183 50-32-8

Benzo[e]pyrene 64112 192-97-2

Bis(2-ethylhexyl) phthalate 63187 117-81-7

9H-Carbazole 63194 86-74-8

Chrysene 64115 218-01-9

Dibenz[a,h]anthracene 64116 53-70-3

Dibenzothiophene 64117 132-65-0

Diethyl phthalate 63202 84-66-2

1,2-Dimethylnaphthalene 64097 573-98-8

1,6-Dimethylnaphthalene 64099 575-43-9

2,6-Dimethylnaphthalene 63167 581-42-0

2-Ethylnaphthalene 64104 939-27-5

Compound name

NWIS 

parameter 

code

CAS

number1

Fluoranthene 63208 206-44-0

9H-Fluorene 64107 86-73-7

Hexachlorobenzene 63631 118-74-1

Indeno[1,2,3-cd]pyrene 64118 193-39-5

2-Methylanthracene 64105 613-12-7

1-Methyl-9H-fluorene 64100 1730-37-6

1-Methylphenanthrene 64101 832-69-9

1-Methylpyrene 64102 2381-21-7

4,5-Methylenephenanthrene 64106 203-64-5

Naphthalene 63220 91-20-3

Pentachloroanisole 64119 1825-21-4

Pentachloronitrobenzene 63650 82-68-8

Perylene 64120 198-55-0

Phenanthrene 63224 85-01-8

Phenanthridine 64121 229-87-8

Pyrene 63227 129-00-0

1,2,4-Trichlorobenzene 64095 120-82-1

2,3,6-Trimethylnaphthalene 64103 829-26-5

2-Fluorobiphenyl (method surrogate) 90754 321-60-8

Nitrobenzene-d5 (method surrogate) 90755 4165-60-0

Terphenyl-d14 (method surrogate) 90756 1718-51-0

1

CAS Registry Number® (CASRN) is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through 

CAS Client Services.

summed C1-, C2-, C3-, C4-, C5-alkylated homolog groups of the 

parent PAH(s).

Purpose and Scope

This report describes all aspects of a method, from 

sample preparation through calculation and reporting of 

results, to determine semivolatile organic compounds and 

polycyclic aromatic hydrocarbons in solids by GC/MS using 

ASE. The new ASE method, USGS NWQL analytical method 

O-5506-06, has two schedules. NWQL schedule 5506 contains 

38 semivolatile organic compounds and PAHs (table 1), and 

schedule 5507 contains all compounds in schedule 5506 plus 

25 alkylated PAH homolog groups (table 2). This new ASE 

method is applicable for determining semivolatile organic 

compounds and PAHs in 25 g of solid sample (a minimum of 

0.5 g of material is required). If it is difficult to obtain a minimum amount of material (as can be the case for collecting suspended sediment on glass-fiber filter paper), filtration of larger 

amounts of water using Teflon filters (Mahler and Van Metre, 

2003) might be preferred and likely will yield sufficient material, which can then be easily removed from Teflon filter paper 

and weighed prior to analysis. The method is rapid, efficient, 

and was developed potentially to replace Soxhlet samplepreparation techniques, such as NWQL method 2502 (Furlong 

and others, 1996) and method 5505 (Olson and others, 2004). 

Because of the inherent complexity of sediment matrices, the 

NWQL strongly suggests that any sampling and analysis plan 

must include matrix spike QC samples for appropriate interpretation of the data. The method is designed so that sample 

extracts also may be used to determine other compounds in 

sediments simply by reprocessing the GC/MS data, without 

requiring additional sample preparation or analysis.

Purpose and Scope 
Table 2. Alkylated polycyclic aromatic hydrocarbon homolog 

groups determined using this method and reported with estimated 

concentrations (schedule 5507).

[NWIS, National Water Information System]

Compound name NWIS

parameter 

C1-alkylated naphthalene 64122

C2-alkylated naphthalene 64123

C3-alkylated naphthalene 64124

C4-alkylated naphthalene 64125

C5-alkylated naphthalene 64126

C1-alkylated phenanthrene/anthracene 64127

C2-alkylated phenanthrene/anthracene 64128

C3-alkylated phenanthrene/anthracene 64129

C4-alkylated phenanthrene/anthracene 64130

C5-alkylated phenanthrene/anthracene 64131

C1-alkylated fluoranthene/pyrene 64132

C2-alkylated fluoranthene/pyrene 64133

C3-alkylated fluoranthene/pyrene 64134

C4-alkylated fluoranthene/pyrene 64135

C5-alkylated fluoranthene/pyrene 64136

C1-alkylated benz[a]anthracene/chrysene 64137

C2-alkylated benz[a]anthracene/chrysene 64138

C3-alkylated benz[a]anthracene/chrysene 64139

C4-alkylated benz[a]anthracene/chrysene 64140

C5-alkylated benz[a]anthracene/chrysene 64141

C1-alkylated benzopyrene/perylene 64142

C2-alkylated benzopyrene/perylene 64143

C3-alkylated benzopyrene/perylene 64144

C4-alkylated benzopyrene/perylene 64145

C5-alkylated benzopyrene/perylene 64146

This method, when combined with other methods of the 

USGS for the determination of organic substances in water 

described previously (Wershaw and others, 1987; Fishman, 

1993; Zaugg and others, 2002), can be used to help evaluate 

environmental fate and transport of more than 200 semivolatile 

organic compounds.

This report describes method performance for the quantitative determination of 38 semivolatile compounds (most of 

which are PAHs). The semiquantitation of 25 alkylated PAH 

homolog groups associated with five parent PAHs also is 

described, but results must be obtained by means of a separate 

request to the NWQL. Method performance (mean bias and 

variability) was determined using Ottawa sand, a commercially available topsoil, and an environmental stream sediment, 

fortified at 1.5 and 15 micrograms per compound. Method 

detection limits (MDLs) were determined according to an 

accepted statistical procedure (U.S. Environmental Protection 

Agency, 1997) using 25-g samples. Although no method performance data are presented for the 25 alkylated PAH homolog groups because of the lack of reference standards, reproducibility data using standard reference material are provided.

Finally, the reproducibility of the method was evaluated 

by using 10 environmental sediment samples. Results for this 

method also were compared to the existing Soxhlet method at 

the NWQL using 28 environmental sediment samples.

This new ASE method is more efficient and cost effective 

for extracting PAH compounds from solids than the NWQL 

Soxhlet method (Olson and others, 2004). It officially was 

approved and implemented at the NWQL in 2006.

Analytical Method

Organic Compounds and Parameter Codes: Polycyclic 

aromatic hydrocarbons, bottom sediment, soils, and solids 

mass per mass, pressurized solvent extraction, solid-phase 

extraction, gas chromatography/mass spectrometry, 

O-5506-06 (see tables 1 and 2)

1. Scope and Application

This new ASE method is suitable for the determination 

of 38 semivolatile organic compounds and polycyclic aromatic 

hydrocarbons (NWQL schedule 5506) and 25 alkylated PAH 

homolog groups (NWQL schedule 5507) in solids by GC/MS. 

The method extracts 25 g of bed sediment (stream and lakebeds), soil, or aqueous suspended sediment (minimum of 0.5-g 

material) to determine the method compounds in microgramper-kilogram concentrations. The method is applicable to 

compounds that are (1) efficiently extracted from sediment 

samples using high-pressure water/isopropyl alcohol, (2) partitioned from the resulting water/isopropyl alcohol extract onto 

the divinylbenzene-vinylpyrrolidone copolymer organic phase, 

(3) volatile and thermally stable for gas chromatography (GC), 

(4) sufficiently stable to chemical and thermal degradation, 

and (5) are amenable to electron impact (EI) mass spectrometry (MS) analysis.

The names of the semivolatile and PAH compounds 

determined using this method, the National Water Information 

System (NWIS) parameter code, and Chemical Abstracts Service (CAS) number for each compound are listed in table 1. 

The alkylated PAH homolog groups that also can be determined using this method (NWQL schedule 5507) and their 

NWIS parameter codes are listed in table 2.

 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
2. Summary of Method

Soil or sediment samples are collected in the field by 

using the sample-collection techniques outlined by Radtke 

(1997), Shelton and Capel (1994), and Mahler and Van Metre 

(2003). Core samples are collected using field techniques 

outlined by Van Metre and others (2004), and suspended sediments are collected using field techniques outlined by Mahler 

and Van Metre (2003). Samples are preserved by freezing 

at −20oC with a 1-year sample-holding time limit (prior to 

sample extraction) from the date of sample collection (U.S. 

Environmental Protection Agency, 1998). This sample-holding 

time limit is provisional until a validated method can be used 

to determine the effectiveness of the sample-freezing procedure.

Surrogate compounds are added to the thawed sample 

prior to extraction using water/isopropyl alcohol on a pressurized solvent extraction system. The method compounds are 

isolated from the water/isopropyl alcohol extracts using disposable, polypropylene solid-phase extraction (SPE) cartridges 

that contain a divinylbenzene-vinylpyrrolidone copolymer 

phase. The SPE cartridges are partially dried for 5 minutes. 

The compounds of interest are eluted from the SPE cartridge 

with a mixture of dichloromethane (DCM) and diethyl ether 

(DEE) at an 80:20, volume-per-volume ratio. The DCM–DEE 

eluent is passed through a sodium sulfate/Florisil SPE cartridge to dry and further clean up the extract. The extract 

volume is reduced to 500 μL, and internal standard compounds 

are added prior to compound determination by capillarycolumn GC/MS.

The instrumental analysis consists of GC separation of 

the compounds followed by mass spectrometric (MS) identification and quantitation. The compounds are separated by GC 

on a fused-silica capillary column using temperature programming to optimize compound resolution. The compounds are 

identified by retention time on the GC column and by comparison of mass spectra to reference spectra obtained from 

authentic standards. The internal standard method is used to 

quantitate the compounds using a multipoint calibration curve.

3. Safety Precautions and Waste Disposal

3.1 Conduct all steps in the method that require the use of 

organic solvents, such as cartridge cleaning, bottle rinsing, 

cartridge elution, and extract concentration, in a fume hood. 

It is necessary to wear eye protection, gloves, and protective 

clothing in the laboratory area and when handling reagents, 

solvents, or any corrosive materials. Typical laboratory disposable nitrile gloves do not provide adequate protection from 

DCM, so be careful to avoid contact with DCM.

3.2 The liquid waste stream produced during sample preparation is about 95-percent water (pH 7 buffer), with the rest 

of the volume made up of organic solvents. These solvents 

include isopropyl alcohol, DEE, acetone, and DCM. 

Collect the wastestream in thick-walled carboys, and dispose 

according to local regulations for chlorinated wastestreams. 

Dispose of solvents used to clean or rinse glassware, equipment, and cartridges in the appropriate waste containers. 

The solid-waste stream produced during sample analysis is 

composed of used SPE cartridges, extracted sediment or soil, 

and assorted glassware (sample vials and pipettes). Dispose of 

the solid-waste stream according to NWQL policy (Maloney, 

2005, section 3.6.6, “Sample Disposal”).

4. Interferences

Samples, collection equipment, ASE extraction cells, 

or SPE cartridges that are handled improperly might become 

contaminated [sample-collection protocols and cleaning procedures for field equipment (Radtke, 1997) must be followed 

(phosphate-free detergent, followed by copious amounts of tap 

water, and then deionized water) as well as thorough cleaning of laboratory equipment]. Compounds that compete with 

or displace the compounds of interest from the SPE cartridge 

materials (divinylbenzene-vinylpyrrolidone copolymer 

phase and Florisil) might cause interferences or low method 

recovery, or both. In addition, coextracted dissolved organic 

material, such as humic and fulvic acids, might reduce the 

SPE extraction efficiency and recoveries of the compounds of 

interest.

Phthalates and preservatives [butylated hydroxy toluene 

(BHT) and related compounds] in the SPE cartridge material 

and housing can potentially contribute to low-concentration 

contamination. For this reason, the analyses of laboratory 

reagent blanks are particularly important to provide information about the presence of laboratory contaminants (most of 

which are not method compounds). A field blank (reagent 

sand heated to 450°C for 4 hours) can be used to help determine if sample collection and equipment-cleaning procedures 

are sufficient to prevent contamination. Comparison of the 

sample with the laboratory blanks is especially important if 

compounds other than method compounds are to be identified 

in full-scan spectra. If interferences are identified in laboratory 

blanks (particularly method compounds), cleaning or replacement of parts might be necessary to remove interference(s) as 

much as possible.

Compounds that have gas-chromatographic retention 

times and characteristic ions with mass-to-charge ratios identical to, or similar to, the compounds of interest might interfere. 

Again, because of the complex nature of sediment and soil 

samples, this background interference might occur frequently.

5. Apparatus and Equipment

The equipment required, along with specific models and 

sources that were used to develop this method, are listed as 

follows.

Analytical Method   
5.1 Cleaning and elution module — For cleaning and preparation of SPE cartridges, Supelco, Inc., Visiprep Solid-Phase 

Extraction Vacuum Manifold or equivalent.

5.2 Pressurized extraction system — Dionex ASETM 200 

Accelerated Solvent Extractor capable of maintaining a pressure of 13,800 kPa (2,000 lb/in2

), and 200°C or equivalent.

5.3 Vacuum tubing — 1.27-cm (0.5 in.) outside diameter 

(OD) by about 3 m (118 in.) length, for drawing sample 

extracts by vacuum through SPE cartridges.

5.4 Extraction cells — Dionex ASE 200 stainless steel 22-

mL extraction cells and end caps with PEEK (PolyEtherEtherKetone).

5.5 Carboy — NalgeneTM, high-density polyethylene, thickwalled, capable of sustaining 200 kPa (29 in. of mercury) mercury vacuum, 10-L volume, Van Waters & Rogers Scientific, 

Inc. (VWR), VWR part no. 36494-090 or equivalent.

5.6 Bottle-top solvent dispensers — Adjustable from 2 to 

5 mL, 5 to 25 mL, and 10 to 100 mL; Brinkman Dispensette, 

VWR or equivalent.

5.7 40-mL receivers (concentrator tubes) — Receivers that 

fit inside the SPE manifold (13 cm in length and 2.5 cm wide), 

tapered for solvent exchange, Allen Scientific Glassblowers, 

Inc. or equivalent.

5.8 Solvent reservoirs for the ASE — Amber glass, 

2,000 mL, Dionex.

5.9 Vacuum pump — Any adjustable vacuum pump with 

sufficient capacity to maintain a vacuum of 200 kPa (29 in. of 

mercury).

5.10 Analytical balances — Balance for accurately weighing samples, 1,000 ± 0.1 g. Balance for standard preparation 

accurately weighs 10 ± 0.01 mg.

5.11 Nitrogen evaporative concentrator — Organomation 

N-Evap Model 124 or equivalent.

5.12 Micropipettes — 50-, 100-, and 200-μL fixed-volume 

and variable-volume micropipettes with disposable glass 

bores; VWR Scientific or equivalent.

5.13 Glass syringes and stepper syringe dispensers — 10- to 

500-μL volumes, Hamilton part no. 83701 or equivalent.

5.14 Adapters and valves — Teflon, connects SPE cartridge 

barrel to male Luer fitting.

5.15 Positive pressure nitrogen manifold — 12-port, 

Supelco.

5.16 Freezer — Upright, capable of storing 100 or more 

1,000-mL widemouthed jars at −20°C.

5.17 Gas Chromatography/Mass Spectrometry Analysis

5.17.1 Gas chromatograph/mass spectrometer— Agilent 

Technologies 5973B MSD coupled to an Agilent Technologies 

6890 GC and equipped with an autosampler, a split/splitless 

injector, and a computer controller (ChemStation instrument 

control and Target data review software) or equivalent. The 

GC system must be suitable for use with capillary-column 

GC analysis (GC conditions, section 8.1.1). Full-scan massspectral data are acquired using this system (MS conditions, 

section 8.2.3).

5.17.2 Syringe — 10 μL; Hamilton Co. Model 80377 for GC 

autosampler.

6. Reagents and Consumable Materials

6.1 Consumable Materials

6.1.1 Helium carrier gas (99.999 percent) — Gas chromatography carrier gas.

6.1.2 Glass fiber thimble — Whatman glass fiber thimble, 

item number 2814199 or equivalent.

6.1.3 Nitrogen gas — For extract concentration, 99.999 

percent pure.

6.1.4 Collection vials — Dionex 60 mL, clear or amber collection vials or equivalent.

6.1.5 Florisil SPE cartridges — 6-mL barrel, packed with 1 

g of Florisil, Argonaut Technologies, catalog number 712-

0100-C or equivalent.

6.1.6 Column reservoir — Teflon 150 mL, empty column, 

custom.

6.1.7 Isolation SPE cartridges — 20-mL barrel, packed with 

1g of divinylbenzene-vinylpyrrolidone copolymer; Oasis HLB 

material, Waters Inc., catalog number 186000117 or equivalent.

6.1.8 Glass sample collection bottles — Amber, 118 to 

472 mL (4 to16 ounces), wide mouth, heated to 450°C for 

4 hours, fitted with Teflon-lined screw caps or equivalent.

6.1.9 Solvents — Dichloromethane (DCM), pentane, 

acetone, isopropyl alcohol, diethyl ether (DEE), ethyl acetate; 

Burdick and Jackson, pesticide grade or equivalent.

   Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
6.1.10 Organic free water — Prepared by Solution 2000 

purification system or equivalent.

6.1.11 Potassium phosphate buffer — pH 7.0 (dilute 10 g 

dipotassium hydrogen phosphate and 7 g potassium dihydrogen phosphate in 1 L reagent water).

6.1.12 Dichloromethane: diethyl ether mixture — 80:20 

(volume-per-volume ratio).

6.1.13 Water: isopropyl alcohol mixtures — 50:50 volumeper-volume, and 20:80 volume-per-volume ratio (v/v).

6.1.14 Sodium sulfate — Aldrich Chemical Co. reagent 

grade or equivalent, heated to 450°C for at least 4 hours.

6.1.15 Reagent sand — Ottawa reagent sand or equivalent, 

Fisher Scientific, Inc., for samples, set spikes, and reagent 

blanks, heated to 450°C for 4 hours.

6.1.16 Glass fiber filter thimbles — 79-mm by 19-mm inside 

diameter by 1.5-mm thickness, heated to 450°C for 4 hours, 

Whatman, Inc., part no. 2814199.

6.1.17 Disposable glass capillaries — To fit the 50- and 

100-μL fixed-volume micropipettes, heated to 450°C for 

4 hours.

6.1.18 PAH surrogate solution — Containing 2-fluorobiphenyl, nitrobenzene-d5

, and terphenyl-d14 obtained as a mixed 

solution at 1,000 μg/mL per component from Supelco, Inc. 

Dilute purchased intermediate concentration solutions to a 

final mixed solution concentration of 40 ng/μL in methanol. 

Other appropriate surrogate compounds and levels can be 

added or substituted after demonstrating acceptable method 

performance.

6.1.19 PAH spike solution — Contains the individual 

semivolatile compounds and PAH compounds listed in table 

1. Four solutions were obtained from Absolute Standards, 

Inc., each containing a subset of the semivolatile compounds. 

Individual compounds in each solution are at concentrations 

of 2,000 ng/μL. Dilute an aliquot of each solution into a single 

final spike solution. The final selected concentration of each 

component is 150.0 ng/μL in ethyl acetate.

6.1.20 Standard reference material (SRM) — Any sediment or soil reference material available to test the method for 

recovery of some or all of the selected compounds may be an 

appropriate quality assurance material. SRM 1944 (a natural 

marine sediment) from the National Institute of Standards and 

Technology (NIST) certified for specific PAH compounds with 

additional uncertified values was used for this study. No single 

SRM currently (2006) available contains all of the compounds 

determined using this method.

6.1.21 Perdeuterated PAH internal standard (dPAHIS) 

solution — Contains the following: 1,4-dichlorobenzene-d4, 

naphthalene-d8, phenanthrene-d10, perylene-d12, acenaphthened10, and chrysene-d12, all at 100 ng/μL in ethyl acetate.

6.2 Gas Chromatograph/Mass Spectrometer

6.2.1 Capillary GC column — Fused-silica, 25 m long by 

0.20-mm inside diameter, internally coated with a 5-percent 

diphenyl and 95-percent dimethyl polysiloxane stationary 

phase with a 0.33-μm film thickness; J&W Scientific columns 

from Agilent Technologies, Ultra 2TM or equivalent.

6.2.2 GC injection-port glass liner — Use any instrumentspecific splitless or direct injection-port liner that provides 

acceptable peak shape and detector response.

6.2.3 GC/MS PAH calibration solution — Prepare working 

solutions of the entire suite of individual PAH compounds 

listed in table 1 at 0.1, 0.2, 0.5, 1.0, 2.5, 5.0, 8.0, 10.0, and 

20.0 ng/μL per component in ethyl acetate using mixed stock 

solutions, including PAH surrogate solution (section 6.1.18). 

Obtain stock solutions from Absolute Standards, Inc., Supelco, 

Inc. or equivalent. Aliquots of the dPAHIS solution (section 6.1.21) are added to each of the calibration solutions 

to produce individual dPAHIS compound concentrations of 

10 ng/μL.

6.2.4 Alkylated PAH homolog retention time source material — Almost any crude oil sample can be used to assign GC 

retention times for alkylated PAH homolog groups and create 

reference mass spectra. The original material used was a sediment sample from the Powell Stream near Knoxville, Tennessee. It was submitted to the NWQL for the National WaterQuality Assessment Program (Station 03532000; sampled 

on December 13, 1995). Optionally, use Alberta Sweet Mix 

Blend (ASMB). ASMB crude is the standard oil used for dispersant-treating tests in the Emergencies Science Division of 

Environment Canada (Wang and others, 1994).

6.2.5 GC/MS quality control/quality assurance solutions — 

Concentrations of selected PAHs in these solutions are measured at periodic intervals within the analytical sequence to 

monitor instrument performance.

6.2.6 Continuing calibration verification (CCV) solution — 

A CCV solution, having individual compound concentrations 

of 2.5 ng/μL, is analyzed between every 10 environmental and 

laboratory quality control (QC) samples, verifying that the 

initial quantitation calibration is maintained.

6.2.7 Instrument detection limit (IDL) solution — An IDL 

solution, having individual compound concentrations of 

0.2 ng/μL, is analyzed (1) at the beginning of the GC/MS 

sequence, and (2) at the end of the analytical sequence. This 

analysis is used to verify instrument performance near the 

Analytical Method 
lowest concentrations of the calibration curve during the entire 

analytical sequence.

6.2.8 Mass spectrometer calibration — A solution of decafluorotriphenylphosphine (DFTPP) is analyzed before the first 

CCV analysis. This analysis verifies the initial mass spectrometer axis calibration and the relative abundance of ions formed 

over the mass range of the analysis. Prepare this solution from 

commercially available neat standards, Ultra Scientific or 

equivalent.

6.2.9 Third-party check (TPC) — A solution of all compounds or selected compounds. The TPC is analyzed after the 

initial calibration sequence to independently verify the instrument calibration. This solution is prepared from a source other 

than that used for preparing calibration standards. Currently 

(2006), a 0.4 ng/μL standard (stock solution from Supelco, 

Inc.) is used.

7. Sample Preparation Procedure

Samples are grouped into sets of up to 10 environmental 

samples (9 samples if an SRM is included), a laboratory spike, 

a laboratory blank, and possibly an SRM.

7.1 Sample Preparation and Quality Control

Retrieve samples that can be stored up to 1 year in a 

freezer, and allow them to thaw completely in a refrigerator 

prior to extraction.

NOTE: Do not allow samples to remain thawed prior to 

extraction in a refrigerator for more than 48 hours.

Thoroughly homogenize each sample with a clean 

spatula or scoopula. If total carbon or organic carbon has been 

requested, remove about a 20-g wet-weight aliquot of sample 

and place in an appropriate container (Wershaw and others, 

1987). Retrieve all paperwork and sample bottles from their 

storage areas. Check that all paperwork has corresponding 

sediment sample, and vice versa.

7.1.1 The ASE 22-mL stainless-steel extraction cells are 

used for this procedure. Obtain 13 cells for up to nine environmental samples, spike, blank, SRM, and an empty cell for 

instrument cleaning. Fill the cleaning cell with sand because 

the extract will not need to be analyzed.

7.1.2 Use a clean razor blade to cut a pre-baked, glass fiber 

extraction thimble (79-mm by 19-mm inside diameter by 

1.5-mm thickness) lengthwise and slightly overlap the edges 

to fit inside a 22-mL extraction cell. Cut off the excess thimble 

(about 10 mm). Place thimbles in all but the instrument cleaning cell.

7.1.3 Record the cell plus thimble weight as the pre-extraction weight.

7.1.4 Fill the laboratory reagent blank and laboratory reagent 

spike cells with sand. Add about 5 to 10 mL of sand to the bottom of the SRM cell. Place 1 to 2 g (dry weight) of SRM 1944 

into an extraction cell with thimble and finish filling the cell 

with sand. Load wet sediment samples into cells while tapping 

gently to ensure cell is full.

NOTE: If the sample is rich in organic content (sooty or 

obviously petroleum based, or organic carbon content has 

previously been determined by analysis to be greater than 

about 5 percent), only add about 1 g of sample (dry weight) 

sandwiched between sand. This is the same procedure used for 

loading the cell containing the SRM.

7.1.5 Bring method PAH surrogate solution (section 6.1.18) 

and spike solutions to room temperature. Vortex each for 

10 seconds to ensure homogeneity. Dispense 100 μL of the 

surrogate mixture into each sample, blank, and spike using a 

100-μL stepper-syringe. Dispense 100 μL of the spike mixture 

into the spike sample with a separate micropipette.

7.1.6 Label two 60-mL collection vials for each sample by 

marking the laboratory ID “ID – 120” for the 120°C extract 

on one vial and “ID – 200” for the 200°C extract on the other 

vial.

7.1.7 Add 3 mL of pentane to the “ID – 200” vials.

7.1.8 Place the extraction cells in the following order on the 

ASE cell tray (upper tray): cleaning cell (filled with sand), 

spike, blank, up to nine environmental samples, and SRM.

7.1.9 Place the 60-mL extract collection vials (labeled as 

in section 7.1.6) on the ASE vial collection tray (lower tray). 

Place the vial for collecting the first ASE cleaning extract in 

the first tray position. Then place 12 appropriately labeled 

vials for collecting the 120°C ASE extracts in the next 12 tray 

positions. Then place 12 more appropriately labeled (in the 

same order) collection vials in tray positions 13 through 25 for 

collecting the 200°C extracts. Place an additional empty vial 

for collecting the ASE cleaning extract in the final position.

7.2 ASE Extraction

7.2.1 Load the Dionex AutoASE sequence (schedule) 

“pah_sediment.sched” for a full set of samples (cleaning cell, 

spike, blank, and up to 10 samples; see table 3). If the set 

contains less than 10 environmental samples, edit the schedule 

to remove extraction cells as needed.

The procedure uses two ASE extraction methods 

(sed120.met and sed200.met, see table 4) so that each sample 

is first extracted at 120oC with isopropyl alcohol (IPA)/water 

(50:50, v/v) and at 200oC with IPA/water (80:20, v/v). The 

method for the extraction at 200oC is identical to the method 

for the 120oC extraction listed in table 4 except the tempera-

 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
ture is set at 200oC and a different solvent bottle is used, which 

contains IPA/water (80:20, v/v).

NOTE: Ensure that two ASE solvent bottles contain sufficient 

IPA/water mixture to complete the extraction (allow about 1 L 

for a full set of 10 samples).

7.2.3 After extraction (allow about 1.5 hours for each 

sample), visually verify that there is between 40 to 50 mL in 

the two 60-mL collection vials for each sample, and check 

the computer-generated ASE sample log to determine if any 

potential problems (leaks, plugging, or mechanical failures) 

were reported that would require the sample extraction to be 

repeated if a sufficient amount of sample is available.

Table 3. An example of an accelerated solvent extraction (ASE) schedule for 13 cells.

[mL, milliliters; ID, identification; SRM, standard reference material]

Vial Cell Method file Rinse (on/off) Rinse bottle Rinse volume 

(mL) Sample ID

1 1 Sed120.met On B 5 Cleaning cell

2 2 Sed120.met On B 5 Set spike

3 3 Sed120.met On B 5 Set blank

4 4 Sed120.met On B 5 Sample 1

5 5 Sed120.met On B 5 Sample 2

6 6 Sed120.met On B 5 Sample 3

7 7 Sed120.met On B 5 Sample 4

8 8 Sed120.met On B 5 Sample 5

9 9 Sed120.met On B 5 Sample 6

10 10 Sed120.met On B 5 Sample 7

11 11 Sed120.met On B 5 Sample 8

12 12 Sed120.met On B 5 Sample 9

13 13 Sed120.met On B 5 Sample 10 (SRM)

14 2 Sed200.met On B 5 Set spike

15 3 Sed200.met On B 5 Set blank

16 4 Sed200.met On B 5 Sample 1

17 5 Sed200.met On B 5 Sample 2

18 6 Sed200.met On B 5 Sample 3

19 7 Sed200.met On B 5 Sample 4

20 8 Sed200.met On B 5 Sample 5

21 9 Sed200.met On B 5 Sample 6

22 10 Sed200.met On B 5 Sample 7

 23 11 Sed200.met On B 5 Sample 8

 24 12 Sed200.met On B 5 Sample 9

 25 13 Sed200.met On B 5 Sample 10 (SRM)

 26 1 Sed200.met On B 5 Cleaning cell

NOTE: It is generally necessary to empty the ASE 60-mL 

rinse collection vials at the end of the day if the extraction is 

scheduled to continue overnight.

7.2.4 After checking that sample extract volumes are acceptable, weigh the cell plus thimble plus dry sample. This weight 

minus the pre-extraction weight is the dry sample weight 

because the final ASE extraction is at 200°C and is followed 

by a 150-second purge using nitrogen gas.

NOTE: When the instrument is performing optimally, the 

sample is dry (as verified by comparing weights to a drying 

balance). However, if the thimble is damp or appears to contain moisture, it indicates that there was a problem during the 

extraction (leak or incomplete extraction), and the extraction 

must be repeated.

Analytical Method 
7.2.5 Refrigerate the ASE extracts (up to 5 days) prior to 

SPE isolation and cleanup. 

7.3 SPE Cartridge Cleaning

7.3.1 Place Teflon adapters on top of the 20-mL Oasis 

SPE cartridges obtained from a vacuum-sealed bag received 

from the manufacturer. Insert the tip of a 150-mL reservoir 

(polypropylene or Teflon) into a Teflon stopcock. Insert the 

reservoir with stopcock in the adapter above the Oasis SPE 

cartridge, and place the assembly on the SPE cleaning and elution module as shown in figure 1.

NOTE: Ensure waste carboy has sufficient empty volume to 

accommodate about 1 L.

7.3.2 Add 20 mL (the SPE barrel volume) of the elution solvent (DCM–DEE, 80:20 v/v) to rinse the Oasis SPE cartridges 

and reservoirs. Allow the solvent to drain by gravity until the 

phase is completely saturated. Then open the Luer-Lok flowcontrol valves on the vacuum manifold by turning them counterclockwise to allow the remaining solvent to be removed 

from the Oasis SPE cartridges by vacuum.

7.3.3 Rinse the cartridges with an additional 10 mL of 

DCM–DEE and allow 5 to 10 minutes for any residual solvent 

to be removed by vacuum (preferably just until visibly dry).

NOTE: Vacuum applied to the SPE cartridges must not 

exceed 10 minutes because laboratory air contains low 

concentrations of some of the method compounds that might 

introduce process contamination.

7.3.4 Attach Florisil SPE cartridges to the cleaning and elution module. Add 10 mL (the SPE barrel volume) of acetone 

to rinse the Florisil SPE cartridges. Allow the solvent to drain 

by gravity until the phase is completely saturated. Then, open 

the Luer-Lok flow-control valves on the vacuum manifold by 

turning them counterclockwise to allow the remaining solvent 

to be removed from the cartridges by vacuum. Rinse the cartridges with an additional 10 mL of acetone, and allow about 

10 minutes for the vacuum to remove residual solvent (preferably just until visibly dry; see previous note).

7.4 SPE Extraction

Set up the SPE extraction module in preparation for 

extracting the ASE extracts according to figure 1.

7.4.1 Place lab ID labels matching the 60-mL collection 

vials on each corresponding cleaned reservoir and Oasis SPE 

cartridge assembly and ensure Teflon stopcocks are in the 

closed position (see fig. 1).

7.4.2 Add the 200°C ASE extract from the 60-mL collection vial to each corresponding reservoir. Add 50 mL of the 

phosphate buffer solution to the empty ASE collection vial. 

Cap and shake collection vial for 5 to 10 seconds. Add this 

rinse to each corresponding reservoir. Repeat the phosphate 

buffer rinse step one additional time, adding it to the appropriate reservoir. Open the Teflon stopcock between the Oasis SPE 

cartridge and the reservoir (fig. 1) to allow gravity to draw the 

ASE extract and buffer rinses through the Oasis SPE cartridges. A small vacuum might have to be applied to start flow 

through the SPE cartridge. Obtain the desired extraction flowrate range (between 10 to 50 mL/min) by opening the vacuum 

manifold Luer-Lok flow-control valves. A small amount of 

vacuum might need to be applied once or twice during sample 

extraction.

7.4.3 Repeat this process (section 7.4.2) with the 120°C ASE 

extract.

NOTE: Reasonable extraction times range from 10 to 20 minutes for each of the 120°C and 200°C ASE extracts.

7.5 SPE Cartridge Drying

Disconnect the SPE cartridges from the reservoir assembly and dry them (but not completely dry) for 5 to 10 minutes 

on a positive pressure nitrogen manifold.

Table 4. An example of an accelerated solvent extraction (ASE) method for a 120°C extraction.

[lb/in2, pounds per square inch; kPa, kilopascal; %, percent; IPA, isopropyl alcohol]

Extraction condition Parameter set point

Pressure 2,000 lb/in2 (13,800 kPa)

Temperature 120°C

Preheat time 0 minutes

Purge during preheat Off

Heat time 6 minutes

Static time 10 minutes

Flush volume 50%

Extraction condition Parameter set point

Purge time 150 seconds

Static cycles 3

Solvent A IPA/water (50:50; volume per volume)

Solvent B 0%

Solvent C 0%

Solvent D 0%

10 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Figure 1. Solid-phase extraction assembly for accelerated solvent extracts 

for use in determining semivolatile organic compounds and polycyclic aromatic 

hydrocarbons.

Teflon stopcock

Teflon adapter

20-milliliter Oasis

solid-phase extraction (SPE) cartridge

SPE cleaning and

elution module

Accelerated solvent

extraction extract in

150-milliliter reservoir

Luer-Lok

flow-control

valves

NOTE: As the SPE phase dries, a lighter color can be 

observed at the wet/dry boundary layer. It is not necessary or 

desirable for the cartridge to dry completely. After the drying 

step, proceed immediately to the SPE elution step. The extract 

is not allowed to be held on the SPE cartridge for this method.

7.6 SPE Cartridge Elution

Set up the SPE extraction module in preparation for cartridge 

elution according to figure 2.

7.6.1 Place a 40-mL SPE receiver for each sample in the 

SPE cleaning and elution module.

7.6.2 Attach the corresponding 150-mL reservoirs (polypropylene or Teflon) to Oasis SPE cartridges with a Teflon 

adapter.

7.6.3 Add ~ 2.5 g baked sodium sulfate to the cleaned Florisil cartridge.

7.6.4 Attach the Florisil cartridge (with sodium sulfate) to 

the bottom of the dried Oasis SPE cartridge. Place this cartridge assembly on the SPE elution module directly above the 

40-mL receiver (fig. 2).

7.6.5 Add 5 mL of the DCM–DEE elution mixture to the 

60-mL ASE collection vial (not shown). Cap and shake collection vial for 5 to 10 seconds by rotating to ensure all the glass 

surfaces have been rinsed. Add this rinse to the corresponding 

reservoir.

7.6.6 Add 10 mL of DCM–DEE to the 150-mL solvent 

reservoir and elute the Oasis SPE cartridge by gravity into 

the 40-mL receiver. Add another 10 mL of the DCM–DEE 

and allow gravity to draw the elution solvent into the 40-mL 

receivers, making sure to thoroughly rinse the sides of the 

reservoir (fig. 2). Repeat this process one more time with 5 mL 

of DCM–DEE.

7.6.7 Using a large syringe or small amount of vacuum, 

force all residual DCM–DEE from the two SPE cartridges. 

The addition of 30 mL of DCM–DEE will result in the collection of about 25 mL of elution solvent. About 5 mL of the 

DCM–DEE will be retained on the SPE beds.

7.6.8 Transfer label from cartridge to receiver and cap 

receiver. Store capped receivers at 4°C or less, or proceed to 

the concentration step.

7.7 Concentration of Extract and Transfer to Vial

7.7.1 Using a nitrogen gas evaporator (N-evap), slowly 

evaporate the sample sxtracts to about 4 mL and add 20 μL of 

the dPAHIS internal standard solution (section 6.1.21).

Analytical Method 11
Solvent

reservoir

Oasis solid-phase 

extraction (SPE) 

cartridge

SPE cleaning 

and elution 

module

Teflon stopcock

Teflon adapter

Teflon adapter

Sodium sulfate

Florisil

40-milliliter

receiver

Figure 2. Solid-phase elution module assembly used in the analytical 

method for determining semivolatile organic compounds and polycyclic 

aromatic hydrocarbons.

7.7.2 Continue evaporation of the extract until the volume is 

reduced to 500 μL.

7.7.3 Vortex each receiver for 10 to 20 seconds, rinsing the 

extract as far up the sides of the receiver as possible.

7.7.4 Transfer the extract with a baked Pasteur pipette into 

a labeled, amber GC autosample vial. Cap vials with Teflonlined screw caps and store at 4°C or less for up to 45 days until 

analysis by GC/MS.

8. Instrumental Analysis

Samples are analyzed by GC/MS using full-scan MS 

analysis. A capillary-column GC system is equipped with an 

autosampler and a split/splitless injection port operated in the 

splitless injection mode and is directly connected to a quadrupole mass spectrometer. A computer system is used to allow 

complete control of the autosampler, GC and MS operations, 

and to acquire, process, and store signals from the GC/MS. 

Complete details of GC/MS operation are beyond the scope of 

this report. Instead, the suggested GC/MS operating conditions and sample sequence used in this method are outlined in 

the following procedure. Users should consult the appropriate 

instrument manuals for additional details regarding general 

GC/MS system operation. Note that the GC/MS operating 

conditions are provided for guidance only. Different GC/MS 

systems will require different operating conditions to achieve 

acceptable instrument performance. Suggested GC/MS operating conditions to achieve acceptable instrument performance 

are indicated below.

8.1 Instrumental Conditions and Setup

8.1.1 Suggested GC-operating conditions for PAHs. Set initial oven temperature at 65°C (hold for 3 minutes), then ramp 

at 6°C/min to 320°C, and hold for 20 minutes to allow for 

sufficient column bake-out; injection port temperature, 285°C 

with electronic pressure control set for constant flow of helium 

gas of 0.7 mL/min, 1 μL, splitless injection.

12  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
8.1.2 Determine compound retention times. Following 

GC/MS setup, establish compound retention times with calibration standards. Peak identifications, retention times, massto-charge ratios, and abundances relative to the quantitation 

ion for PAHs, using the GC operating conditions described in 

section 8.1.1 with a J&W Scientific Ultra 2TM column from 

Agilent Technologies, are listed in table 5 for method compounds and homolog groups. The relative ion abundances are 

not provided for the alkylated PAH homolog groups because 

the ratios are different among isomers. The determination 

of retention times for the alkylated PAH homolog groups is 

described in section 8.1.3.

NOTE: Because of differences in GC columns, even from the 

same manufacturer, and operational characteristics between 

instruments, the elution profiles will vary. Therefore, it is critical to verify instrument-specific compound retention times. 

Use single-component standards to verify retention times and 

mass spectra of closely eluting or coeluting compounds. Verify 

retention times following any GC maintenance procedures 

applied to the capillary columns to improve chromatography.

Table 5. Retention times, relative retention times, gas chromatography/mass spectrometry quantitation ions, confirmation ions, and 

percent relative abundance of confirmation ions for individual method compounds and alkylated polycyclic aromatic hydrocarbon (PAH) 

homolog groups.

[Compounds are reported in chromatographic elution order; min, minute; compounds followed by RR are method internal standards and are followed by a 

designation (RR-1, RR-2...), which indicates their order as a retention reference; m/z, mass-to-charge ratio]

Compound (retention time order)

Retention 

time 

(min)

Relative 

retention 

time 

Retention 

reference 

compound

Quantitation 

ion 

(m/z)

Confirmation 

ions 

(m/z)

Percent relative 

to quantitation 

ion abundance

1,4-Dichlorobenzene-d4 (RR-1) 6.8 1.000 1 152 150, 115 150, 60

Nitrobenzene-d5 (surrogate) 8.6 1.265 1 128 82, 98 280, 40

1,2,4-Trichlorobenzene 11.0 1.554 1 180 182, 185 95, 25

Naphthalene-d8 (RR-2) 11.0 1.000 2 136 none

Naphthalene 11.1 1.009 2 128 129, 102 10, 10

C1-alkylated naphthalene1 14.0 1.272 2 141 142, 127 variable

2-Fluorobiphenyl (surrogate) 15.3 1.391 2 172 171, 85 30, 10

2-Ethylnaphthalene 15.9 1.445 2 141 156, 115 45, 25

2,6-Dimethylnaphthalene 16.1 1.464 2 141 156, 115 140, 25

C2-alkylated naphthalene1 16.1 1.464 2 141 156, 115 variable

1,6-Dimethylnaphthalene 16.5 1.500 2 141 156, 115 125, 25

Acenapthylene 16.6 .937 3 152 151, 76 20, 30

1,2-Dimethylnaphthalene 17.2 1.564 2 151 156, 115 70, 25

Acenaphthene-d10 (RR-3) 17.7 1.000 3 162 164, 80 100, 40

Acenaphthene 17.8 1.006 3 153 154, 152 95, 50

2,3,6-Trimethylnaphthalene 19.1 1.079 3 170 155, 153 100, 25

C3-alkylated naphthalene1 19.5 1.102 3 170 155, 153 variable

Diethyl phthalate 19.6 1.122 3 149 177, 176 25, 10

9H-Fluorene 19.8 1.186 3 166 165, 82 95, 15

1-Methyl-9H-fluorene 22.0 1.243 3 180 165, 89 130, 30

Hexachlorobenzene 22.2 1.244 3 284 286, 142 80, 40

Pentachloroanisole 22.4 1.254 3 265 267, 280 65, 90

Dibenzothiophene 23.0 1.284 3 184 139, 922 15, 5

C4-alkylated naphthalene1 23.0 1.286 3 184 169, 141 variable

Pentachloronitrobenzene 23.3 0.998 4 237 214, 142 70, 80

Phenanthrene-d10 (RR-4) 23.3 1.000 4 188 189, 94 15, 20

Analytical Method 13
Compound (retention time order)

Retention 

time 

(min)

Relative 

retention 

time 

Retention 

reference 

compound

Quantitation 

ion 

(m/z)

Confirmation 

ions 

(m/z)

Percent relative 

to quantitation 

ion abundance

Phenanthrene 23.4 1.004 4 178 176, 89 20, 15

Anthracene 23.6 1.013 4 178 176, 89 20, 15

C5-alkylated naphthalene1 23.9 1.026 4 198 183 variable

Phenanthridine 24.2 1.034 4 179 178, 151 20, 15

9H-Carbazole 24.4 1.043 4 167 168, 139 15, 10

2-Methylanthracene 25.6 1.100 4 192 191, 96 45, 10

4,5-Methylenephenanthrene 25.7 1.103 4 190 189, 94 90, 10

C1-alkylated phenanthrene/anthracene1 25.8 1.107 4 192 191, 95 variable

Anthraquinone 26.7 1.136 4 208 180, 152 100, 85

C2-alkylated phenanthrene/anthracene1 28.0 1.202 4 206 191 variable

Fluoranthene 28.1 1.206 4 202 101, 203 20, 15

Pyrene 28.8 1.236 4 202 101, 203 20, 15

1-Methylphenanthrene 25.9 1.112 4 192 191, 942 55, 5

C3-alkylated phenanthrene/anthracene1 29.6 1.270 4 220 205 variable

Terphenyl-d14 (surrogate) 29.9 1.238 4 244 122, 245 25, 20

C4-alkylated phenanthrene/anthracene1 31.0 1.330 4 234 219 variable

C1-alkylated fluoranthene/pyrene1 31.0 1.330 4 216 215, 108 variable

1-Methylpyrene 31.1 1.335 4 216 215, 108 70, 20

C2-alkylated fluoranthene/pyrene1 32.0 1.373 4 230 215 variable

Benz[a]anthracene 33.4 .994 5 228 229, 226 20, 25

Chrysene-d12 (RR-5) 33.6 1.000 5 240 120, 241 25, 20

Chrysene 33.7 1.003 5 228 229, 114 20, 20

Bis(2-ethylhexyl) phthalate 34.5 1.029 5 149 167, 279 35, 10

C3-alkylated fluoranthene/pyrene1 34.6 1.030 5 244 229 variable

C1-alkylated benz[a]anthracene/

chrysene1

35.8 1.065 5 242 241, 227 variable

C5-alkylated phenanthrene/anthracene1 36.4 1.083 5 248 233 variable

C4-alkylated fluoranthene/pyrene1 36.9 .951 6 258 243 variable

C2-alkylated benz[a]anthracene/

chrysene1

37.3 1.110 5 256 241 variable

Benzo[b]fluoranthene 37.5 .966 6 252 253, 126 20, 25

Benzo[k]fluoranthene 37.6 0.969 6 252 253, 126 20, 25

Benzo[e]pyrene 38.4 .990 6 252 250, 126 30, 20

Benzo[a]pyrene 38.6 .995 6 252 250, 126 25, 20

Perylene-d12 (RR-6) 38.8 1.000 6 264 260, 132 25, 30

Perylene 38.9 1.003 6 252 250, 126 25, 25

C1-alkylated benzopyrene/perylene1 39.8 1.026 6 266 251 variable

C5-alkylated fluoranthene/pyrene1 39.8 1.026 6 272 257 variable

Table 5. Retention times, relative retention times, gas chromatography/mass spectrometry quantitation ions, confirmation ions, and 

percent relative abundance of confirmation ions for individual method compounds and alkylated polycyclic aromatic hydrocarbon (PAH) 

homolog groups.—Continued

[Compounds are reported in chromatographic elution order; min, minute; compounds followed by RR are method internal standards and are followed by a 

designation (RR-1, RR-2...), which indicates their order as a retention reference; m/z, mass-to-charge ratio]

14  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Compound (retention time order)

Retention 

time 

(min)

Relative 

retention 

time 

Retention 

reference 

compound

Quantitation 

ion 

(m/z)

Confirmation 

ions 

(m/z)

Percent relative 

to quantitation 

ion abundance

C3-alkylated benz[a]anthracene/

chrysene1

41.1 1.059 6 270 255 variable

C2-alkylated benzopyrene/perylene1 42.0 1.082 6 280 265 variable

Indeno[1,2,3-cd]pyrene 42.0 1.082 6 276 138, 137 30, 20

C4-alkylated benz[a]anthracene/

chrysene1

42.1 1.085 6 284 269 variable

Dibenz[a,h]anthracene 42.2 1.088 6 278 139, 279 30, 25

Benzo[g,h,i]perylene 42.7 1.101 6 276 138, 274 40, 20

C3-alkylated benzopyrene/perylene1 43.2 1.113 6 294 279 variable

C5-alkylated benz[a]anthracene/

chrysene1

44.8 1.155 6 298 283 variable

C4-alkylated benzopyrene/perylene1 45.0 1.160 6 308 293 variable

C5-alkylated benzopyrene/perylene1 45.4 1.170 6 322 307 variable

1

Analysis of PAH homolog groups can be obtained by a separate request to the U.S. Geological Survey National Water Quality Laboratory.

2

 The ion abundance relative to the quantitation ion is less than 10 percent; and therefore the ion is used as a monitoring ion and not as a confirmation ion.

8.1.3 Determine retention-time intervals for each alkylated 

PAH homolog group. Because authentic standards are not 

available for most of the substituted PAHs, retention times for 

these groups are determined by using an alkylated PAH homolog standard reference material (section 6.2.4). The reference 

sample is analyzed at about 20 ng/μL. Extracted ion chromatograms are created using the quantitation and confirmation ions 

for each alkylated PAH homolog group. The retention times 

are determined for the first and last isomers for each alkylated PAH homolog group. Quantitation of the alkylated PAH 

homolog groups is explained in section 9.2.

8.1.4 Prior to each analytical sequence, assess GC/MS 

performance by examining peak shape, efficiency of separation for closely eluting compound pairs, and response-factor 

variation determined for the compounds. CCVs bracket every 

10 samples and are the primary indicator of changes in instrument performance during an analytical sequence.

8.2 GC/MS Tuning and Calibration

8.2.1 Tune the GC/MS prior to analysis or after any instrument maintenance using automated or other tuning procedures 

as prescribed by the system manufacturer. Prior to any analysis, verify the GC/MS tune and mass axis calibration by injecting a solution of decafluorotriphenylphosphine (DFTPP). The 

relative mass fragment abundance and mass assignments need 

to be within the range of values specified by the U.S. Environmental Protection Agency (2004b) for method 8270c.

8.2.2 Calibration of the instrument adheres to all aspects set 

forth in the NWQL’s Quality Management System (Maloney, 

2005), as do all sections of this method that involve quality 

assurance (QA) and quality control (QC). Analyze appropriate calibration solutions (section 6.2.3, a 5-point calibration 

curve is required) and determine a best-fit calibration curve 

for each compound using the curve-fitting routines provided 

by the instrument manufacturer. Carefully inspect the curves 

to ensure a correlation coefficient (r2) of 0.995 or greater and 

verify that the lowest calibration standard level meets the QA 

criteria outlined below. Calibration curve-fitting routines based 

on the relative response factor (RRF) are used to obtain a calibration curve for each compound. A linear calibration curve is 

suggested for most of the method compounds; however, other 

curve-fitting routines (quadratic curves and power curves) 

might be used for polar compounds. The same curve-fitting 

routine that demonstrates the “best fit” to the data for each 

compound must always be used in the method.

Check the calibration using the third-party check solution (section 6.2.9), which should result in ± 25 percent of 

expected concentrations. If these QA criteria cannot be met, 

the source of the problem must be identified and corrected 

before a new calibration curve is used. If necessary, perform 

instrument maintenance or prepare new calibration standards 

Analytical Method 15

Table 5. Retention times, relative retention times, gas chromatography/mass spectrometry quantitation ions, confirmation ions, and 

percent relative abundance of confirmation ions for individual method compounds and alkylated polycyclic aromatic hydrocarbon (PAH) 

homolog groups.—Continued

[Compounds are reported in chromatographic elution order; min, minute; compounds followed by RR are method internal standards and are followed by a 

designation (RR-1, RR-2...), which indicates their order as a retention reference; m/z, mass-to-charge ratio]
or a new TPC solution. After calibration results are determined 

to be acceptable, assemble samples, set QC samples, mass 

spectrometer verification solutions, continuing calibration 

verification solutions, and instrument detection limit solutions 

into an analytical sequence, and analyze them under GC/MS 

conditions identical to those used for the calibration. A typical 

analytical sequence is listed in table 6. The quality (optical 

clarity) of the sample extracts and number of samples that 

need to be analyzed in the sequence might affect the CCV 

frequency. Use an automated sample injection system to inject 

1 μL of the appropriate sample extract or standard solution 

into the GC/MS.

Table 6. Gas chromatography/mass spectrometry analytical 

sequence suggested for use with this method.

[PAH, polycyclic aromatic hydrocarbon]

Analytical 

sequence Sample type

1 Decafluorotriphenylphosphine mass spectrometer 

calibration solution

2 Instrument blank (injection of pure solvent)

3 Instrument detection level (IDL) solution

4 Continuing calibration verification (CCV) solution

5 Set PAH spike

6 Set blank

7 Sample 1

8 Sample 2

9 Sample 3

10 Sample 4

11 Sample 5

12 Sample 6

13 Sample 7

14 Sample 8

15 CCV

16 Sample 9

17 Sample 10

18 Sample 11

19 Sample 12

20 Sample 13

21 Set quality-control reference material sample

22 CCV

23 IDL

8.2.3 The MS source temperature is kept at 200°C and the 

GC/MS transfer line at 290°C. Data acquisition conditions 

for full scan range from 45 to 450 amu, scanned at a rate of at 

least 2 scans per second (5–10 scans per peak), with the filament operated at 70 eV. Store all data electronically for subsequent qualitative identification, quantitation, and archiving.

8.3 Qualitative Identification

8.3.1 Qualitative criteria and single-component identification. The criteria outlined in this section apply for reporting 

compounds for all sample results in blanks, spikes, or environmental samples. Two criteria are evaluated when establishing 

a positive compound identification: expected relative retention 

time and comparative agreement of the mass spectrum.

The relative retention time (RRT) is the retention time of 

the compound normalized to the retention time of the assigned 

internal standard compound. The assigned internal standard is 

generally the perdeuterated polycyclic aromatic hydrocarbon 

in the dPAHIS mixture that elutes at a retention time nearest 

the compound of interest. The formula for determining RRT is

RRT = ,

Tc

Tis

where

Tc = retention time (referenced to the start of the 

analysis) for the compound of interest, and

Tis = retention time of the internal standard assigned 

to that compound.

Determine the RRT for each sample compound by 

analyzing standard solutions and internal standards under 

identical instrument conditions. The RRTs for compounds 

in samples and standards need to agree within 1 percent, and 

the expected RRT for samples must be within ± 0.1 minute. 

The RRT of a compound must be within the expected retention time window (± 0.1 minute), in the absence of coeluting 

interference that might cause retention time shifts, to meet the 

required qualitative criteria.

The second component for qualitative identification is 

comparison of reference standard mass spectra and sample 

spectra. The reference standard mass spectra are derived 

from authentic compound standards collected under identical GC/MS conditions as the sample spectra. The GC/MS 

operator must visually compare reference spectra, integrated 

ion ratios of the quantitation ion to two confirmation ions, and 

the elution of ion profiles to determine if the spectral match 

between standards and samples is reasonable. Peak area ratios 

of the quantification and qualifier ions must agree within 

± 20 percent between standards and samples for concentrations greater than the minimum reporting level (MRL) in 

the absence of any obvious coeluting interference. Some of 

the method compounds have confirmation ions (table 5) that 

have abundances below 10 percent of the quantification ion. 

Confirmation of these compounds at concentration levels well 

below the MRL might be more difficult because the ion ratios 

can be more variable than the required ± 20 percent. The ion 

profiles for the quantification and qualification ions also must 

maximize within 2 scans (about 1 second) of each other in the 

absence of any obvious coeluting interference.

(1)

16 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
8.3.2 Qualitative identification of the alkylalted PAH homolog groups. Using the approach of Wang and others (1994) 

and the extracted ion chromatograms as a reference, critically 

examine peaks within a retention time window for spectral 

confirmation and typical alkylated PAH homolog group patterns. Because of the variability in ion ratios between isomers 

for the mulitcomponent groups, there are no rigid acceptance 

criteria. Sum the responses for all homolog peaks within the 

expected retention time window that match their extracted 

qualifier ion profiles (table 5), or expected ion profile patterns 

as shown for the C4- and C5-alkylated phenanthrene/anthracenes in Olson and others (2004, fig. 2). Note that a characteristic group of peaks is summed to yield a single concentration estimate. The spectra for peaks that make a substantial 

contribution to the total area need to be examined to ensure 

that they match with the reference mass spectrum. If not, their 

contribution to the total concentration is subtracted.

9. Calculation and Reporting of Results

The concentration of a compound is calculated after it 

has met qualitative criteria for retention time and mass spectral 

agreement (see section 8.3.1).

9.1 Determination of Single-component Compound 

Concentrations

The weight of sediment extracted in this method is 

limited by the extraction cell size (22-mL) and the amount of 

material that can be loaded into the cell. The dry weight of the 

sediment sample (in grams) is obtained after it is extracted at 

200°C according to the following equation:

Ws = [(Wcell + Wthimble) + Ws] post-extraction – 

(Wcell + Wthimble) pre-extraction,

where

Ws = dry weight of sediment extracted, in 

 grams;

Wcell = weight of ASE extraction cell, in grams;

Wthimble = weight of glass fiber thimble, in grams.

Calculate the compound concentration in the sample, as 

follows:

Concentration (μg/kg) = (CFr) × (Vf) / (Ws)

where

CFr = on-column concentration determined by 

calibration curve-fitting routines, in 

nanograms per microliter;

Vf = method pre-determined volume of extract 

(500 μL); and 

Ws = dry weight of sediment extracted, in grams.

Calibration curve-fitting routines based on the relative 

response factor (RRF) are used to obtain a calibration curve 

for each compound. They are provided by the instrument manufacturer and summarized in Furlong and others (1996). If the 

calculated concentration of a compound in a sample exceeds 

the highest concentration point of the calibration curve, dilute 

the extract to bring the compound response within the range of 

the calibration curve and reanalyze the extract. If curvefitting routines (linear, quadratic, and power curves) are used 

for calibration, verify that the sample compound response is 

not outside the working range of the calibration curve.

9.2 Calculation of Multicomponent Alkylated PAH 

Homolog Concentrations

Each alkylated PAH homolog group is composed of 

many discernable isomers, most without authentic reference 

standards. Manually integrate (all manual integrations are 

automatically identified for confirmation in secondary review) 

the isomer peak areas based on the appropriate quantitation 

ions (table 5) present in their expected retention time window 

range, subtracting any significant peaks that do not match the 

reference mass spectrum. Using the calibration curves for the 

compounds selected to represent each homolog group listed 

in table 7, calculate the concentration of each alkylated PAH 

homolog group listed in table 5. Reported concentrations are 

considered semiquantitative and reported as estimated (“E” 

remark code). If interferences are determined to be present 

within the integrated isomeric peaks (based upon comparison 

of mass spectra), then manually integrate that portion of the 

ion chromatogram corresponding to the interference and subtract its peak area from the total peak area.

9.3 Reporting Units

Report compound concentrations for field samples in 

micrograms per kilogram (μg/kg) dry sediment. Report surrogate data for each sample type as percent recovered and to 

three significant figures. Report data for the set spike and quality-control reference material samples as percent recovered. 

Compounds quantified in the set blank sample are reported in 

micrograms per kilogram of sand. Report compound concentrations for field samples to two significant figures.

9.4 Reporting Levels

Method detection limits (MDLs) using the procedures 

outlined by the U.S. Environmental Protection Agency (1997) 

have been calculated for this method and are discussed further in section 11. The MDL for each compound is used to 

determine the minimum reporting levels (MRLs). The MRLs 

have been established at two to five times the calculated MDL. 

Report qualitatively identified compound concentrations that 

are less than the MRL as estimated (“E” remark code) concentrations. The lowest quantitative threshold for reporting data 

has been set at 1 percent of the MRL. Compounds that are not 

detected are reported as being less than the MRL. Concentrations of alkylated PAH homolog groups that meet qualitative 

(2)

(3)

Analytical Method 17
identification criteria are always reported as estimated with the 

“E” remark code.

ney, 2005). Based on initial blank (sand) results (table 8, 

section 11), method compounds are not anticipated to have 

chronic blank problems.

NOTE: Laboratory blanks will be evaluated annually (similar 

to the long-term method detection level) to reevaluate blank 

contamination for determining if reporting levels need to be 

updated (William Foreman, U.S. Geological Survey, written 

commun., 2005).

10.2 Laboratory Spike

The percent recovery from the laboratory reagent spike 

(LRS) is calculated from the spiking procedure described in 

sections 7.1.4 and 7.1.5. A 22-mL ASE cell filled with Ottawa 

sand (about 25 g) is spiked with 1.5 μg per compound, and 

the recoveries are calculated based on the amount spiked. 

The recovery is used to monitor method performance for 

the sample preparation set without considering the effects of 

sample matrix. The LRS results are compiled for long-term 

recovery performance used for creating control limits and 

charts. Control limits for the LRS are updated annually using 

3 times F-pseudosigma of the LRS results from the previous year. If the recovery of a compound is not within control 

limits, the data can be transmitted three ways: estimated (“E” 

remark coded), a raised reporting level, or the data are reported 

as “deleted – ruined” (D – R). Before continuing, the source 

of the problem must be identified and corrected. If surrogate 

compound recoveries fall outside the QC criteria, corrective 

actions are taken (Maloney, 2005).

10.3 Surrogate Compounds

Surrogate standards are compounds similar in physical 

and chemical properties to the method compounds but are not 

expected to be present in the environment. They are added to 

each environmental and QA/QC sample and used to monitor 

preparatory steps, matrix effects, and overall method performance. Their recoveries are not used to correct compound 

concentrations in environmental samples. Typically, surrogate 

recoveries from at least 30 LRBs and LRSs are used to update 

QC criteria for each surrogate annually. Specific corrective 

actions are employed if surrogate(s) recoveries fall outside the 

QC criteria (Maloney, 2005).

18  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids

Table 7. Compounds with relative response factors used for the quantitation of alkylated 

polycyclic aromatic hydrocarbon homologs.

[C1–C5, alkylated polycyclic aromatic hydrocarbon homolog series consisting of C1, C2, C3, C4, C5 groups; 

RRFs, relative response factors]

Compound RRFs used for calculations Homolog series

2,6-Dimethylnaphthalene C1-C5 alkylated naphthalene

2-Methylanthracene C1-C5 alkylated phenanthrene/anthracene

1-Methylpyrene C1-C5 alkylated fluoranthene/pyrene

Benz[a]anthracene C1-C5 alkylated benz[a]anthracene/chrysene

Benzo[a]pyrene C1

-C5 alkylated benzopyrene/perylene isomers

10. Quality Assurance and Quality Control

The NWQL has prepared a laboratory Quality Management System document (Maloney, 2005) and quality-assurance and quality-control (QA/QC) guidance document (M.R. 

Burkhardt and T.J. Maloney, U.S. Geological Survey, written 

commun., 1998) for Analytical Services. These documents are 

followed in this method to establish and verify data quality 

and provide corrective actions for each QC sample type. The 

analyst uses laboratory quality-control data from reagent blank 

and spike samples, surrogate standards, and CCVs to determine if corrective actions are necessary. Standard reference 

material and instrumental checks provide external verification 

of method performance and are considered quality-assurance 

samples.

10.1 Laboratory Blank

The laboratory reagent blank (LRB) is an analyte- and 

matrix-free (Ottawa sand) sample with minimal compound 

interferences. The LRB is used to monitor the entire sample 

preparation and analytical procedure for possible laboratory contamination. Currently (2006) the blank is considered 

acceptable when a compound is undetected or detected at less 

than the MRL. However, the level of blank contamination will 

affect reporting data and the need for data qualifiers (Maloney, 

2005). The concentrations of any compounds detected in the 

LRB sample are reported only if they first meet the qualitative 

identification criteria outlined in section 8.3.1 (specifically for 

all compound or ion retention times, ion ratios and mass spectra). The concentration of any compound detected in the LRB 

is not subtracted from the amount detected in environmental 

samples. Rather, if there are interferences that would prevent 

the analysis of a compound, the source of contamination is 

determined and eliminated before continuing (Maloney, 2005).

If method compounds are detected at any concentration 

level in greater than 10 percent of the historical laboratory 

blanks, they are considered to be chronic blank compounds 

and are treated as if they are present in all samples (Malo-
10.4 Continuous Calibration Verification (CCV)

The CCV solutions are simply calibration solutions that 

are used to monitor the instrument’s stability in comparison to 

the initial calibration curve. They bracket the environmental 

samples in the analytical sequence. The CCV control limits are 

established at ± 25 percent of the expected concentration for 

each compound. Instrument maintenance is generally required 

(cleaning the MS source, replacing the injection port liner, 

or clipping off about 1 loop of the GC column) to correct for 

CCV failures. After instrument maintenance, it is necessary to 

repeat the initial calibration. If a CCV fails the QC criteria, the 

affected samples are reanalyzed.

10.5 Decafluorotriphenylphosphine (DFTPP) Tuning

A DFTPP sample is analyzed at the beginning of each 

analytical sequence. It is used to assess mass spectrometer performance, such as sensitivity and resolution. The relative mass 

fragment abundance and mass assignments must be within the 

range of values specified by the U.S. Environmental Protection 

Agency (1997), and if these criteria cannot be met, cleaning 

the MS source is usually required, and furthermore, samples 

cannot be analyzed until the DFTPP tuning and fragmentation 

criteria are met.

10.6 Instrument Detection Limit (IDL)

The IDL solution is an aliquot of a low concentration 

calibration solution (0.2 ng/μL) representing compound concentrations near, but greater than, their respective MDLs. They 

bracket the samples in the analytical sequence, and the control 

limits are established at ± 25 percent of the expected concentration for each compound. If an IDL fails the QC criteria, the 

affected samples require reanalysis.

10.7 Third-party Check Solution

The third-party check solution is made independently 

from the other standard solutions. Typically it contains all the 

analytes in the method or at least one from every compound 

class at a concentration near the midpoint of the calibration 

curve. It is analyzed after establishing a new calibration curve, 

and calculated compound concentrations need to be within 

±25 percent of the expected value. Maintaining the instrument 

will usually bring the third-party check solution back into 

compliance before samples can be analyzed.

10.8 Internal Standard Compounds

Internal standard compounds are added to automatically 

correct quantitative results for slight differences in extract 

volume (if the volume is not exactly 0.5 mL), as well as compensate for differences in the injected sample volume. They 

are also used to monitor and compensate for unexpected GC 

compound retention time shifts by providing RRT markers.

10.9 Standard Reference Material (SRM)

Standard reference materials (SRMs) received from an 

independent third party provide a matrix representative of 

environmental samples, and thus, an independent assessment 

of method performance. These reference materials typically 

are certified for a limited number of the compounds of interest. The SRM sample is prepared and analyzed with each 

analytical set. SRM samples provide information about the 

method long-term recovery performance; however, there are 

no process control criteria based on the SRM.

10.10 Matrix Spikes

The NWQL strongly suggests that field projects include 

matrix spikes in the QC sample design as a measure of method 

performance specific to their study area. An amount equivalent 

to 1.5 μg per analyte is spiked at the laboratory into the customer requested matrix samples, and the spike recovery range 

(based on criteria from the initial method validation study) is 

expected to be 60 to 120 percent. However, some sediment 

matrices might not yield the anticipated recoveries because 

of inherent difficulties in producing a uniform, thoroughly 

mixed spike sample, or because equilibration times needed to 

incorporate the compounds of interest differ widely in diverse 

sediment matrices (Northcott and Jones, 2000). Analysis of 

duplicate samples also is encouraged for evaluating reproducibility of results at environmental concentrations.

11. Results and Discussion of Method 

Validation

11.1 Mean Bias and Precision

Reagent-sand samples; stream-sediment samples collected from Cherry Creek near Garland Park, Denver, Colorado; and soil samples from a commercially available topsoil 

mixture were used to test method performance. Subsamples 

of each matrix were fortified at 1.5 and 15 μg for each method 

compound. In addition, samples of the three sample matrices 

were extracted and analyzed unfortified to determine the ambient concentrations of any method compounds (table 8).

Each fortified sample set was extracted and analyzed 

on different days, so comparisons of different matrices and 

concentrations include day-to-day variation. Mean bias and 

precision data from the analyses of the three matrices spiked at 

the higher amount (15 μg) are listed in table 9. Final recoveries 

were adjusted as footnoted by subtracting the mean concentrations measured in the unfortified samples. The natural compound contributions of the stream sediment to the 15-μg spike 

varied from 1.1 percent for benz[a]anthracene to 5.9 percent 

for bis(2-ethylhexyl) phthalate. The only compound contribution for the topsoil, bis(2-ethylhexyl) phthalate, contributed 

4.1 percent to the 15-μg spike. Laboratory reagent spikes and 

laboratory reagent blanks were processed with each set of 

samples. The recovery for 1,2,4-trichlorobenzene for the 15-μg 

spike samples was less than 60 percent (table 9), probably 

because the compound is subject to volatility loses during 

sample preparation and solvent reduction steps; thus, the concentration of 1,2,4-trichlorobenzene will always be reported as 

estimated with the “E” remark code.

Analytical Method 19
 Compound 

(retention time order)

Average concentration (μg/kg)

Sand 

n = 14

Stream 

sediment 

n = 3

Topsoil 

n = 3

1,2,4-Trichlorobenzene < MRL < MRL < MRL

Naphthalene < MRL < MRL < MRL

2-Ethylnaphthalene < MRL < MRL < MRL

2,6-Dimethylnaphthalene < MRL < MRL < MRL

1,6-Dimethylnaphthalene < MRL < MRL < MRL

Acenaphthylene < MRL < MRL < MRL

1,2-Dimethylnaphthalene < MRL < MRL < MRL

Acenaphthene < MRL < MRL < MRL

2,3,6-Trimethylnaphthale < MRL < MRL < MRL

9H-Fluorene < MRL < MRL < MRL

Diethyl phthalate < MRL < MRL < MRL

1-Methyl-9H-fluorene < MRL < MRL < MRL

Hexachlorobenzene < MRL < MRL < MRL

Pentachloroanisole < MRL < MRL < MRL

Dibenzothiophene < MRL < MRL < MRL

Pentachloronitrobenzene < MRL < MRL < MRL

Phenanthrene < MRL 58.1 < MRL

Anthracene < MRL 39.6 < MRL

Phenanthridine < MRL < MRL < MRL

 Compound 

(retention time order)

Average concentration (μg/kg)

Sand 

n = 14

Stream 

sediment 

n = 3

Topsoil 

n = 3

9H-Carbazole < MRL < MRL < MRL

2-Methylanthracene < MRL < MRL < MRL

4,5-Methylenephenanthrene < MRL < MRL < MRL

1-Methylphenanthrene < MRL < MRL < MRL

Anthraquinone < MRL 27.8 < MRL

Fluoranthene < MRL 88.3 < MRL

Pyrene < MRL 85.6 < MRL

1-Methylpyrene < MRL < MRL < MRL

Benz[a]anthracene < MRL 15.8 < MRL

Chrysene < MRL 19.8 < MRL

Bis(2-ethylhexyl) phthalate < MRL 88.5 620.0

Benzo[b]fluoranthene < MRL 35.0 < MRL

Benzo[k]fluoranthene < MRL 24.1 < MRL

Benzo[e]pyrene < MRL < MRL < MRL

Benzo[a]pyrene < MRL 28.4 < MRL

Perylene < MRL < MRL < MRL

Indeno[1,2,3-c,d]pyrene < MRL < MRL < MRL

Dibenz[a,h]anthracene < MRL < MRL < MRL

Benzo[g,h,i]perylene < MRL 40.6 < MRL

Table 8. Semivolatile and polycyclic aromatic hydrocarbon compounds detected in unfortified reagent-sand, stream-sediment, and 

topsoil samples.

[μg/kg, micrograms per kilogram; < MRL, less than minimum reporting level; n, number of samples]

20 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids

The mean bias and precision data for the three matrices 

spiked at 1.5 μg are listed in table 10.
Table 9. Polycyclic aromatic hydocarbon and semivolatile compound mean bias and precision of spike recovery data for nine 

replicates with compounds spiked at 15 micrograms per sample in reagent-sand, stream-sediment, and topsoil samples.

[μg , micrograms; μg/kg, micrograms per kilogram; RSD, relative standard deviation; sed, sediment]

Compound name 

(retention time order)

Mean recovery (percent) RSD (percent)

Sand Stream sed Topsoil Sand Stream sed Topsoil

1,2,4-Trichlorobenzene1 56.6 52.0 52.5 7.0 7.6 7.0

Naphthalene 67.1 59.3 65.2 9.2 6.8 4.9

2-Ethylnaphthalene 77.5 78.4 82.2 10.1 6.6 4.4

2,6-Dimethylnaphthalene 79.2 80.2 82.4 10.5 6.3 4.4

1,6-Dimethylnaphthalene 79.4 81.3 82.2 10.0 6.0 4.4

Acenaphthylene 68.0 68.5 79.2 5.3 4.4 4.3

1,2-Dimethylnaphthalene 81.8 82.9 84.0 11.1 5.7 4.2

Acenaphthene 74.7 78.0 74.8 5.7 5.0 5.9

2,3,6-Trimethylnaphthalene 89.5 93.8 94.4 14.3 5.9 5.2

9H-Fluorene 81.1 88.4 87.4 5.4 4.0 7.0

Diethyl phthalate 76.6 66.0 59.2 12.5 13.0 9.7

1-Methyl-9H-fluorene 84.2 94.9 92.9 5.8 4.2 7.3

Hexachlorobenzene 77.0 86.9 80.2 5.9 5.4 6.1

Pentachloroanisole 80.2 89.9 86.1 5.0 3.8 6.4

Dibenzothiophene 87.4 98.7 95.2 5.5 4.1 7.8

Pentachloronitrobenzene 84.8 92.1 108.4 16.5 6.0 7.7

Phenanthrene 89.3 97.6* 94.7 4.5 6.5 5.2

Anthracene 88.2 94.4* 96.1 6.4 6.9 5.7

Phenanthridine 92.2 95.0 95.7 5.8 6.1 5.9

9H-Carbazole 95.6 100.6 100.8 5.9 7.8 5.3

2-Methylanthracene 86.0 93.7 99.1 6.8 7.3 5.7

4,5-Methylenephenanthrene 90.0 96.0 93.3 5.7 8.2 5.2

1-Methylphenanthrene 89.7 95.7 92.7 5.4 7.8 4.9

Anthraquinone 99.4 106.2* 109.4 5.8 9.4 5.7

Fluoranthene 94.3 107.2* 106.0 5.8 15.0 6.0

Pyrene 94.9 106.8* 105.7 6.5 13.9 5.6

1-Methylpyrene 92.2 102.1 109.0 9.4 9.5 7.1

Benz[a]anthracene 87.0 98.3* 97.7 6.3 7.2 6.8

Chrysene 86.8 97.4* 91.1 4.5 7.5 7.8

Bis(2-ethylhexyl) phthalate 82.4 69.4* 62.8* 16.2 11.4 24.6

Benzo[b]fluoranthene 85.6 101.2 97.7* 15.7 6.8 4.2

Benzo[k]fluoranthene 81.7 92.7 85.8* 12.8 5.5 4.3

Benzo[e]pyrene 78.6 94.2 92.4 8.5 4.5 12.1

Benzo[a]pyrene 83.0 92.8 90.2* 5.8 7.7 4.4

Perylene 74.1 86.3 85.2 5.0 4.9 5.1

Indeno[1,2,3-c,d]pyrene 86.0 98.4 119.0 12.3 5.3 4.9

Dibenz[a,h]anthracene 83.6 96.0 106.2 11.5 6.0 4.1

Benzo[g,h,i]perylene 80.3 96.3 99.3* 11.8 4.0 4.4

Analytical Method  21
Compound name 

(retention time order)

Mean recovery (percent) RSD (percent)

Sand Stream sed Topsoil Sand Stream sed Topsoil

Surrogate compounds

Nitrobenzene-d5 83.1 53.7 63.8 22.1 11.6 8.2

2-Fluorobiphenyl 85.6 64.5 72.2 19.3 6.3 4.2

Terphenyl-d14 99.6 93.8 99.3 13.9 8.8 4.9

1

Concentration will be qualified in reports as estimated because recovery is less than 60 percent or variability is greater than 25 percent RSD.

*

Percent recovery corrected for background concentration from the average of three unspiked samples.

Table 10. Polycyclic aromatic hydrocarbons and semivolatile compound mean bias and precision of spike recovery data for nine 

replicates with compounds spiked at 1.5 micrograms per sample in reagent-sand, stream-sediment, and topsoil samples.

[μg , micrograms; μg/kg, micrograms per kilogram; RSD, relative standard deviation; sed, sediment; MDL, method detection limit]

Compound name (retention 

time order)

Mean recovery (percent) RSD (percent)

Sand Stream sed Topsoil Sand Stream sed Topsoil

1,2,4-Trichlorobenzene1 49.6 49.5 50.8 13.2 6.8 12.5

Naphthalene 67.0 65.6 59.2 6.6 3.2 12.0

2-Ethylnaphthalene 83.6 83.2 71.2 5.3 4.3 7.9

2,6-Dimethylnaphthalene 86.5 85.9 73.4 5.7 4.8 8.1

1,6-Dimethylnaphthalene 86.0 86.5 73.2 4.8 3.8 7.9

Acenaphthylene 83.7 83.3 69.3 6.1 4.5 8.0

1,2-Dimethylnaphthalene 91.0 90.5 73.5 5.9 5.2 8.3

Acenaphthene 89.6 89.6 63.7 5.7 4.9 8.2

2,3,6-Trimethylnaphthalene 92.3 90.5 75.9 6.7 4.3 11.2

9H-Fluorene 94.4 93.9 71.1 6.0 5.0 9.5

Diethyl phthalate 86.0 83.2 71.3 17.6 7.5 9.7

1-Methyl-9H-fluorene 100.4 98.5 75.6 9.9 6.1 11.2

Hexachlorobenzene 96.6 95.1 54.3 8.5 5.3 25.6

Pentachloroanisole 96.5 95.3 64.2 9.3 5.1 16.7

Dibenzothiophene 105.0 104.3 78.0 8.8 6.9 10.9

Pentachloronitrobenzene 91.4 91.8 82.6 8.1 4.9 12.0

Phenanthrene 102.2 102.6* 82.1 7.3 5.8 10.4

Anthracene 103.3 103.6* 85.6 6.6 5.8 10.7

Phenanthridine 99.1 101.2 82.9 10.1 6.9 10.4

9H-Carbazole 102.4 101.8 84.4 7.8 6.4 11.2

2-Methylanthracene 102.6 102.8 80.2 7.3 5.7 13.5

4,5-Methylenephenanthrene 105.9 106.2 81.9 6.8 5.7 10.8

1-Methylphenanthrene 110.7 110.7 81.8 7.1 6.4 11.7

Anthraquinone 117.1 117.6* 94.4 6.9 7.4 10.7

Fluoranthene 110.8 111.1* 89.2 6.8 6.1 11.0

Pyrene 112.7 113.2* 89.7 6.8 6.2 11.5

Table 9. Polycyclic aromatic hydocarbon and semivolatile compound mean bias and precision of spike recovery data for nine 

replicates with compounds spiked at 15 micrograms per sample in reagent-sand, stream-sediment, and topsoil samples.—Continued

[μg , micrograms; μg/kg, micrograms per kilogram; RSD, relative standard deviation; sed, sediment]

22  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Compound name (retention 

time order)

Mean recovery (percent) RSD (percent)

Sand Stream sed Topsoil Sand Stream sed Topsoil

1-Methylpyrene 113.1 113.5 83.5 6.7 6.4 13.0

Benz[a]anthracene 102.2 102.5* 75.7 7.6 6.2 19.7

Chrysene 101.8 102.2* 73.4 7.6 6.1 19.1

Bis(2-ethylhexyl) phthalate 127.6 124.1* 38.8* 12.6 7.5 21.2

Benzo[b]fluoranthene 95.5 95.4 67.7* 8.0 6.6 18.5

Benzo[k]fluoranthene 95.8 96.0 62.9* 7.0 5.0 19.9

Benzo[e]pyrene 98.9 98.9 67.7 7.0 5.3 14.0

Benzo[a]pyrene 98.2 98.2 77.6* 8.2 6.0 12.7

Perylene 87.4 86.4 68.7 6.4 4.6 10.5

Indeno[1,2,3-c,d]pyrene 102.4 102.6 69.5 7.3 6.1 19.3

Dibenz[a,h]anthracene 97.4 98.6 62.1 8.5 6.5 21.1

Benzo[g,h,i]perylene 98.6 98.3 70.5* 7.9 7.2 18.0

Surrogate compounds

Nitrobenzene-d5 62.7 61.8 66.3 12.2 6.5 27.4

2-Fluorobiphenyl 69.2 68.4 77.1 6.3 3.5 22.2

Terphenyl-d14 109.1 109.7 139.9 6.7 5.3 20.9

1

Concentration is estimated because recovery is less than 60 percent or variability is greater than 25 percent RSD.

*

Percent recovery corrected for background concentration from the average of three unspiked samples.

Table 10. Polycyclic aromatic hydrocarbons and semivolatile compound mean bias and precision of spike recovery data for nine 

replicates with compounds spiked at 1.5 micrograms per sample in reagent-sand, stream-sediment, and topsoil samples.—Continued

[μg , micrograms; μg/kg, micrograms per kilogram; RSD, relative standard deviation; sed, sediment; MDL, method detection limit]

The recoveries of PAH and semivolatile compounds from 

a 22-mL ASE cell filled with Ottawa sand (about 25 g) fortified at 1.5 μg per compound (table 10) averaged 88 percent 

± 9.4 percent relative standard deviation.

Even though sediment matrices provide some retention of 

spiked compounds, they often add to the variability of measured results because of background matrix effects. This variability might be expected to be greater at the lower concentration spike level (table 10) than at the higher level (table 9) for 

the compounds that required recovery correction for ambient 

concentrations in the unspiked sample (the relevant compounds have been footnoted in tables 9 and 10); however, this 

trend was not always observed when comparing the standard 

deviations listed in tables 9 and 10.

Table 11 lists compounds that were investigated in the 

development of this method but were excluded because of low 

recovery, or are not expected to partition into the sediment 

based on Log Kow, or are available in more suitable NWQL 

methods.

In addition to determining the mean bias and precision 

data for the three matrices spiked at 1.5 μg (table 10), the initial method detection limits (MDLs) also were calculated for 

compounds spiked into Ottawa reagent-sand samples according to an accepted statistical procedure (U.S. Environmental 

Protection Agency, 1997) described in section 11.2.

11.2 Method Detection Limits

The NWQL uses the long-term method detection level 

procedure (Childress and others, 1999) to determine compound-reporting conventions for water analytical methods. 

Because of the varied nature of sediment samples, the longterm method detection level (LT–MDL) procedure has not 

been implemented for sediment analyses.

Method detection limits (MDLs) were established using 

procedures outlined by the U.S. Environmental Protection 

Agency (1997). For this method, the MDL was determined 

from the nine replicate reagent spike (Ottawa sand) samples 

fortified at 1.5 μg per compound (table 10). For the set of nine 

samples, the sample standard deviation was computed and the 

MDL calculated from the following formula:

MDL = S × t

(n–1, 1–α= 0.99),

where

S = standard deviation of replicate analyses, 

in microgram per kilogram, at the lowest 

spike concentration;

n = number of replicate analyses; and

t

(n–1, 1–α= 0.99) = Student’s t-value for the 99-percent 

confidence level with n–1 degrees of 

freedom.

(4)

Analytical Method  23
Table 11. Mean bias and precision of spike recovery data for nine replicates with compounds spiked at 1.5 and 15 micrograms per 

sample in reagent-sand, stream-sediment, and topsoil samples for compounds that are not included in this method.

[μg , micrograms; μg/kg, micrograms per kilogram; RSD, relative standard deviation]

Compound name

(retention time order)

Log 

Kow1

Spike

amount

(μg)

Mean recovery (percent) RSD (percent)

Sand Stream 

sediment Topsoil Sand Stream sediment Topsoil

Phenol 1.5 1.5 47.6 47.3* 79.0* 6.2 2.7 36.3

15.0 28.2 26.4* 28.0* 7.2 5.9 4.9

p-Cresol 2.1 1.5 70.3 70.3* 63.3* 9.2 5.5 16.6

15.0 49.9 44.9* 40.1* 10.2 11.0 3.7

Isophorone 2.6 1.5 38.1 37.7 15.8 20.4 7.5 20.3

15.0 18.4 11.3 11.0 5.8 3.6 0.8

2,4-Dichlorophenol 3.1 1.5 87.8 90.9 67.7 13.6 9.9 11.8

15.0 70.8 69.6 76.9 12.4 9.1 10.3

Quinoline 2.1 1.5 56.9 55.3 23.1 16.8 9.3 20.2

15.0 28.5 17.2 16.1 10.1 4.8 2.9

Isoquinoline 2.1 1.5 63.0 62.3 25.1 13.6 8.5 18.1

15.0 31.7 18.8 17.9 12.1 5.9 2.3

2,4,6-Trichlorophenol 3.5 1.5 94.7 95.7 95.2 8.1 7.0 10.9

15.0 82.6 88.1 125.6 12.8 5.9 6.5

Dimethyl phthalate 1.6 1.5 35.1 32.1 80.8 44.8 8.8 35.7

15.0 31.2 15.1 14.6 16.4 4.9 3.0

Pentachlorophenol 4.8 1.5 11.7 11.5 42.3* 9.0 0.9 26.1

15.0 9.0 18.7 34.7* 6.1 5.2 47.8

Di-n-octyl phthalate 8.1 1.5 14.9 14.6 30.6 13.8 1.2 22.8

15.0 30.4 10.4 4.9 26.5 1.6 2.0

1

Log Kow calculated using the U.S. Environmental Protection Agency’s exposure assessment tools and models (EPI-suite software, WSKOWWINTM version 1.40; U.S. Environmental Protection Agency, 2004a).

*

Percent recovery corrected for background concentration in the unspiked sample.

The calculated MDL for each compound is listed in 

table 12 using the 1.5-μg per compound spike in reagent-sand 

results from table 10 and assuming a 25-g sample size (60 

μg/kg). The initial minimum reporting levels (MRLs) for compounds have been assigned based on a combination of MDL 

data, observed matrix interferences, and the impact of varied 

matrices on instrument performance.

The calculated initial MDLs averaged 14 μg/kg. The 

MRLs have been established at 50 μg/kg, or about two to 

five times greater than the calculated initial MDLs for most 

compounds (table 12). This precaution reduces the risk of 

reporting that a compound is less than the MRL (undetected), 

when it is actually in the sample near the MDL concentration 

(Childress and others, 1999). The MRLs for the alkylated PAH 

homolog groups also have been established at 50 μg/kg on 

the basis of the MRLs for the compounds selected to represent each group (table 7). The concentrations for qualitatively 

identified compounds detected less than the MRL are reported 

as estimated, regardless of the established MRL, because 

this method is classified as an “information-rich” method, as 

are other mass spectrometric methods (Childress and others, 

1999).

A few compounds were spiked at a higher concentration 

than the suggested amount (U.S. Environmental Protection 

Agency, 1997) of two to five times the calculated MDL concentrations, and, therefore, the MDL has been defined as an 

“estimated MDL” in those cases, as footnoted in table 12.

11.3 Performance Data Using SRM 1944

SRM 1944 is natural marine sediment that contains 

specific PAH concentrations certified by the National Institute of Standards and Technology (NIST). Many alkylated 

PAH homolog groups are present but are not certified. Nine 

SRM 1944 samples were extracted and analyzed by this ASE 

24  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Table 12. Initial method detection limits calculated from the precision data reported in table 10 for the nine 

replicate reagent-sand samples spiked at 60 micrograms per kilogram per compound.

[μg/kg, micrograms per kilogram; %, percent; MDL, method detection limit; MRL, minimum reporting level]

 Compound name

(retention time order)

Spike amount

(μg/kg)

Mean recovery

(percent)

Initial MDL

(μg/kg)

Initial MRL

(μg/kg)

Naphthalene1 60 67.0 7.7 50

2-Ethylnaphthalene1 60 83.6 7.7 50

2,6-Dimethylnaphthalene1 60 86.5 8.5 50

1,6-Dimethylnaphthalene1 60 86.0 7.2 50

Acenaphthylene1 60 83.7 8.9 50

1,2-Dimethylnaphthalene1 60 91.0 9.2 50

Acenaphthene1 60 89.6 8.9 50

2,3,6-Trimethylnaphthalene1 60 92.3 10.8 50

9H-Fluorene1 60 94.4 9.8 50

Diethyl phthalate 60 86.0 26.4 50

1-Methyl-9H-fluorene 60 100.4 17.3 50

Hexachlorobenzene 60 96.6 14.3 50

Pentachloroanisole 60 96.5 15.5 50

Dibenzothiophene 60 105.0 16.0 50

Pentachloronitrobenzene 60 91.4 12.9 50

Phenanthrene 60 102.2 12.9 50

Anthracene1 60 103.3 11.9 50

Phenanthridine 60 99.1 17.3 50

9H-Carbazole 60 102.4 13.9 50

2-Methylanthracene 60 102.6 13.0 50

4,5-Methylenephenanthrene1 60 105.9 12.5 50

1-Methylphenanthrene 60 110.7 13.7 50

Anthraquinone1 60 117.1 14.0 50

Fluoranthene1 60 110.8 13.0 50

Pyrene1 60 112.7 13.2 50

1-Methylpyrene1 60 113.1 13.1 50

Benz[a]anthracene 60 102.2 13.4 50

Chrysene 60 101.8 13.5 50

Bis(2-ethylhexyl) phthalate 60 127.6 27.9 50

Benzo[b]fluoranthene 60 95.5 13.3 50

Benzo[k]fluoranthene1 60 95.8 11.6 50

Benzo[e]pyrene1 60 98.9 12.0 50

Benzo[a]pyrene 60 98.2 13.9 50

Perylene1 60 87.4 9.8 50

Indeno[1,2,3-c,d]pyrene 60 102.4 12.9 50

Dibenz[a,h]anthracene 60 97.4 14.4 50

Benzo[g,h,i]perylene 60 98.6 13.5 50

1,2,4-Trichlorobenzene2 60 49.6 11.4 50

1

The compound was fortified at a concentration that was higher than five times the calculated MDL. Therefore, the MDL has been 

defined as an estimated MDL.

2

Concentration is permanently estimated with the “E” remark code because recovery is less than 60 percent or variability is greater than 

25 percent relative standard deviation.

Analytical Method  25
method during a 2-month period, and results were compared 

to NWQL Soxhlet extraction method 2502 (table 13). Method 

precision for the certified PAH compounds by the ASE method 

ranged from about 7 to15 percent.The NIST certified results 

for SRM 1944 were obtained by 36-hour Soxhlet extraction 

with DCM and GC/MS analysis, so NIST certified results 

might be expected to be more comparable to NWQL method 

2502 than this ASE extraction method. Hawthorne, Grabanski, 

and others (2000) have suggested that water-based extraction 

solvents cause clay particles to swell much more than typical 

organic solvents. Consequently, PAH molecules that are highly 

sequestered in clay pores are more available to subcritical 

water. The recovery results (table 13) of low molecular weight 

PAH compounds (for example, naphthalene, phenanthrene, 

and anthracene) are greater by 10 to 20 percent for this ASE 

method than by Soxhlet extraction with DCM and probably 

reflect this effect. As the solubility of higher molecular weight 

PAH compounds decreases in the hot IPA/water mixture, 

ASE recoveries generally are comparable to Soxhlet extraction with DCM. Hawthorne, Trembley, and others (2000) 

also observed this same trend for subcritical water extraction of SRM 1944 at 250oC. The relatively high recovery of 

dibenz[a,h]anthracene (132 percent, see table 13) most likely 

is the result of poorly resolved GC peaks contributing to the 

peak area, similar to the situation observed for poor GC peak 

resolution of benzo[b]fluoranthene and benzo[k]fluoranthene 

in SRM 1944 ASE extracts.

Table 14 lists mean concentrations of alkylated PAH 

homolog groups that are present in SRM 1944 but which are 

not reported by NIST. The Soxhlet extraction results for the 

alkylated PAHs were obtained by NWQL custom method 

8022, which is the same as NWQL method 2502 (36-hour 

Soxhlet extraction with DCM).

It is impossible to compare absolute recoveries for the 

homolog groups in SRM 1944, as was possible for the parent 

PAHs (table 13), because there are no NIST-certified values; 

however, Soxhlet and ASE results are similar for those homolog groups that were detected (table 14). All of the relative 

standard deviations (RSDs) are 12 percent or less, indicating 

consistent integration and reproducible extraction efficiency.

11.4 Replicate Environmental Sample Results Using ASE 

Extraction

Nine duplicates and one triplicate sample were extracted 

using ASE to evaluate the reproducibility of the method 

(table 15).

For statistical purposes, the average deviation can be 

used for comparing results of two or three samples (Anderson, 

1987). The average deviation (percent) was calculated for the 

10 replicate samples in table 15 according to the following 

equation:

AD = [1 / n (| R1 R | + | R2 R | + 

| R3 R |)] * 100 / R

where

AD = average deviation, in percent;

n = number of samples (2 for duplicates or 3 for 

triplicates);

R = result 1 to 3; and

R = mean value.

Average deviations to evaluate method reproducibility are 

listed in table 16. Although replicate data for only 10 samples 

is not sufficient to adequately evaluate the reproducibility of 

this method, the observed average deviation ranges for the 

method compounds (table 16) provide an initial assessment. 

The mean average percent deviation of PAH compounds for 

41 duplicate core samples extracted by Soxhlet extraction (Van 

Metre and others, 2004) ranged from 8.2 percent for anthracene to 15.4 percent for chrysene. The 10 duplicate sample 

results for the PAH compounds determined by this ASE 

method demonstrated greater average deviation (about 50 percent) than for the Soxhlet method of extraction used for core 

samples, most likely because of greater variation in the carbon 

content and matrix type of these samples (table 15) than for 

the core samples.

11.5 Accelerated Solvent Extraction (ASE) and Soxhlet 

Sample Results

Extraction results for ASE and Soxhlet for 28 sediment 

samples (including the average values for the 10 replicate 

samples, section 11.4) consist of a wide variety of mixed 

sample types (sand, silt, clay, soil, and soil cores) and organic 

carbon content. These results are listed in table 17.

The correlations (table 18) between the two extraction 

methods were calculated for each detected compound (excluding a few high results from sample extracts that required significant dilutions as footnoted in table 17; however, the ASE 

concentrations were much higher than the Soxhlet concentrations for all points that were not included).

(5)

26 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Table 13. Concentrations certified by the National Institute of Standards and Technology for Standard Reference Material 1944 

determined by Soxhlet extraction and this method.

[NIST, National Institute of Standards and Technology; μg/kg, micrograms per kilogram; SOX, Soxhlet; ASE, accelerated solvent extraction; RSD, relative 

standard deviation; n, number = 7 by Soxhlet, number = 9 by ASE]

Compound name

NIST 

certified 

(μg/kg)

Mean 

SOX 

(μg/kg)

Mean 

ASE 

(μg/kg)

SOX 

recovery 

(percent)

ASE 

recovery 

(percent)

SOX RSD 

(percent) 

n=7

ASE RSD 

(percent) 

n=9

Anthracene 1,770 1,440 1,877 81.3 106.0 7.79 10.26

Benz[a]anthracene 4,720 3,870 3,660 81.9 77.5 6.78 7.77

Benzo[b]fluoranthene1 3,870 3,160 3,050 81.7 98.9 8.63 8.32

Benzo[k]fluoranthene1 2,300 2,920 3,050 127.0 98.9 7.30 8.32

Benzo[ghi]perylene 2,840 1,680 1,893 59.2 66.6 7.05 13.24

Benzo[a]pyrene 4,300 3,170 3,363 73.6 78.2 7.61 12.08

Benzo[e]pyrene 3280 2,480 2,410 75.6 73.5 6.67 9.81

Chrysene 4,860 4,470 5,370 92.1 110.5 7.22 8.95

Dibenz[a,h]anthracene 424 347 561 81.8 132.2 7.38 8.13

Fluoranthene 8,920 6,670 8,970 74.8 100.5 6.07 10.69

Indeno[1,2,3-cd]pyrene 2,780 2,820 2,300 102.0 82.7 6.77 14.82

Naphthalene 1,650 820 1,980 49.3 120.0 10.5 15.70

Perylene 1,170 740 742 63.3 63.4 7.13 9.97

Phenanthrene 5,270 3,970 5,723 75.3 108.6 6.36 8.76

Pyrene 9,700 6,580 9,397 67.8 96.8 5.53 9.32

1

Because of poor chromatographic peak shape, benzo[b]fluoranthene and benzo[k]fluoranthene were nearly unresolved when the ASE extracts were analyzed, 

so ASE concentrations were averaged for these two compounds.

Analytical Method  27
Table 14. Concentrations of alkylated homolog groups detected in Standard Reference Material 1944 determined by Soxhlet extraction 

and this method, but not reported by the National Institute of Standards and Technology.

[μg/kg, micrograms per kilogram; SOX, Soxhlet; ASE, accelerated solvent extraction; RSD, relative standard deviation; NR, not reported; n, number = 7 by 

Soxhlet, number = 9 by ASE]

Compound name

Mean 

SOX 

(μg/kg)

Mean 

ASE 

(μg/kg)

SOX RSD (percent) 

n=7

ASE RSD (percent) 

n=9

C1-alkylated naphthalene 1,090 1,847 12 10

C2-alkylated naphthalene 2,630 3,990 9 9

C3-alkylated naphthalene 6,180 7,053 8 3

C4-alkylated naphthalene NR NR

C5-alkylated naphthalene NR NR

C1-alkylated phenanthrene/anthracene 5,630 6,840 12 4

C2-alkylated phenanthrene/anthracene 6,110 6,677 6 7

C3-alkylated phenanthrene/anthracene 3,330 4,623 8 12

C4-alkylated phenanthrene/anthracene NR NR

C5-alkylated phenanthrene/anthracene NR NR

C1-alkylated fluoranthene/pyrene 7,930 9,277 7 9

C2-alkylated fluoranthene/pyrene 5,430 6,210 10 9

C3-alkylated fluoranthene/pyrene NR NR

C4-alkylated fluoranthene/pyrene NR NR

C5-alkylated fluoranthene/pyrene NR NR

C1-alkylated benz[a]anthracene/chrysene 4,570 3,897 8 6

C2-alkylated benz[a]anthracene/chrysene 1,980 NR 8

C3-alkylated benz[a]anthracene/chrysene NR NR

C4-alkylated benz[a]anthracene/chrysene NR NR

C5-alkylated benz[a]anthracene/chrysene NR NR

C1-alkylated benzopyrene/perylene 4,860 3,637 10 10

C2-alkylated benzopyrene/perylene NR NR

C3-alkylated benzopyrene/perylene NR NR

C4-alkylated benzopyrene/perylene NR NR

C5-alkylated benzopyrene/perylene NR NR

28  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Table 15. Replicate environmental sample results, in micrograms per kilogram, using accelerated solvent extraction.

[Lab ID, laboratory identification number; %, percent; OC, organic carbon; ND, not determined; RT, retention time; R1, result one; R2, result two; AD, average 

deviation, in percent; nd, not detected]

Compound

Lab ID: 20022910084 20022950052 20031220119 20020450012

Matrix / % OC: Clay / 3.2 Clay / 3.1 Core / ND Clay / ND

(RT order) R1 R2 AD1 R1 R2 AD1 R1 R2 AD1 R1 R2 AD1

Naphthalene 13 12 4 20 12 25 24 18 14

2-Ethylnaphthalene 7 5 17

2,6-Dimethylnaphthalene 35 27 13 62 35 28 204 110 30 72 44 24

1,6-Dimethylnaphthalene 11 8 16 17 10 26 46 20 39 24 15 23

Acenaphthylene 4 2 33 25 10 43 5 nd ND

1,2-Dimethylnaphthalene 20 10 33

Acenaphthene 28 10 47

9H-Fluorene 12 nd ND 23 15 21 25 23 4

Diethyl phthalate 16 nd ND

1-Methyl-9H-fluorene

Dibenzothiophene 7 6 8

Phenanthrene 24 18 14 39 31 11 99 66 20 44 36 10

Anthracene 8 6 14 14 9 22 42 22 31 7 9 13

Phenanthridine

9H-Carbazole

2-Methylanthracene 24 15 23

4,5-Methylenephenanthrene 10 7 18 42 32 14 8 8 0

1-Methylphenanthrene 36 26 16 5 3 25

Anthraquinone 20 nd ND

Fluoranthene 37 19 32 57 38 20 241 150 23 47 33 18

Pyrene 33 15 38 50 29 27 193 120 23 35 25 17

1-Methylpyrene 26 15 27

Benz[a]anthracene 11 7 22 14 9 22 96 99 2 15 13 7

Chrysene 25 12 35 26 19 16 124 145 8 27 24 6

Bis(2-ethylhexyl) phthalate 195 100 32 117 84 16

Benzo[b]fluoranthene 14 6 40 18 10 29 123 115 3 28 23 10

Benzo[k]fluoranthene 15 6 43 17 9 31 118 98 9 31 18 27

Benzo[e]pyrene 102 136 14 11 8 16

Benzo[a]pyrene 15 8 30 110 155 17 10 10 0

Perylene 715 600 9 659 600 5

Indeno[1,2,3-c,d]pyrene 126 184 19 27 20 15

Dibenz[a,h]anthracene 4 nd ND 

Benzo[g,h,i]perylene 109 135 11 20 18 5

Analytical Method  29
Compound

Lab ID: 20013060058 20013060057 20011930041 20031780065

Matrix / % OC: Clay / 5.4 Clay / 6.4 Clay / 0.3 Soil / ND

(RT order) R1 R2 AD1 R1 R2 AD1 R1 R2 AD1 R1 R2 AD1

Naphthalene 22 25 6 43 32 15 9 9 0

2-Ethylnaphthalene

2,6-Dimethylnaphthalene 116 192 25 216 140 21 9 7 10 10 15 20

1,6-Dimethylnaphthalene 38 64 25 66 25 45

Acenaphthylene 28 40 18 45 35 13 46 32 18

1,2-Dimethylnaphthalene

Acenaphthene 46 28 24 27 24 6 45 72 23

9H-Fluorene 33 42 12 48 45 3 50 35 18

Diethyl phthalate

1-Methyl-9H-fluorene 12 12 0 8 4 33

Dibenzothiophene 18 29 23 38 34 6 39 27 18

Phenanthrene 251 400 23 658 500 14 745 630 8 17 12 17

Anthracene 69 100 18 139 100 16 159 110 18

Phenanthridine 16 20 11

9H-Carbazole 90 140 22 197 170 7 108 110 1

2-Methylanthracene 17 19 6 30 18 25 23 15 21

4,5-Methylenephenanthrene 66 110 25 138 100 16 104 79 14

1-Methylphenanthrene 22 42 31 54 37 19 42 34 11

Anthraquinone 204 300 19 466 380 10 230 233 1

Fluoranthene 1,060 1,800 26 2,290 1,600 18 1,770 1,400 12 33 12 47

Pyrene 783 1,300 25 1,700 1,200 17 1,260 1,000 12 28 11 44

1-Methylpyrene 25 49 32 55 35 22 34 27 11

Benz[a]anthracene 276 450 24 615 400 21 450 435 2 10 18 29

Chrysene 618 970 22 1,380 850 24 700 670 2 17 10 26

Bis(2-ethylhexyl) phthalate 212 350 25 406 180 39 78 87 5

Benzo[b]fluoranthene 600 1,100 29 1,360 980 16 655 664 1 11 8 16

Benzo[k]fluoranthene 532 900 26 895 740 9 475 600 12 12 7 26

Benzo[e]pyrene

Benzo[a]pyrene 413 670 24 766 590 13 456 430 3 10 6 25

Perylene

Indeno[1,2,3-c,d]pyrene 520 900 27 1,050 780 15 407 600 19

Dibenz[a,h]anthracene 126 200 23 259 155 25 85 48 28

Benzo[g,h,i]perylene 451 700 22 896 620 18 344 500 18

Table 15. Replicate environmental sample results, in micrograms per kilogram, using accelerated solvent extraction.—Continued

[Lab ID, laboratory identification number; %, percent; OC, organic carbon; ND, not determined; RT, retention time; R1, result one; R2, result two; AD, average 

deviation, in percent; nd, not detected]

30 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Compound

Lab ID: 20031780064 20022410090

Matrix / % OC: Soil / ND Silt / 13.3

(RT order) R1 R2 AD1 R1 R1 R2 AD1

Naphthalene 102 60 35 37

2-Ethylnaphthalene

2,6-Dimethylnaphthalene 109 122 6 677 540 800 13

1,6-Dimethylnaphthalene

Acenaphthylene

1,2-Dimethylnaphthalene

Acenaphthene

9H-Fluorene

Diethyl phthalate

1-Methyl-9H-fluorene

Dibenzothiophene

Phenanthrene 14 30 36

Anthracene

Phenanthridine

9H-Carbazole

2-Methylanthracene

4,5-Methylenephenanthrene

1-Methylphenanthrene

Anthraquinone

Fluoranthene 20 50 43

Pyrene 17 40 40

1-Methylpyrene

Benz[a]anthracene 18 18 0

Chrysene 20 32 23

Bis(2-ethylhexyl) phthalate 241 100 160 30

Benzo[b]fluoranthene 14 22 22

Benzo[k]fluoranthene 15 24 23

Benzo[e]pyrene

Benzo[a]pyrene 19 24 12

Perylene

Indeno[1,2,3-c,d]pyrene 16 18 6

Dibenz[a,h]anthracene 6 8 14

Benzo[g,h,i]perylene 11 15 15

1

The average deviation (AD), in percent, was calculated using equation 5 (Anderson, 1987).

Analytical Method  31

Table 15. Replicate environmental sample results, in micrograms per kilogram, using accelerated solvent extraction.—Continued

[Lab ID, laboratory identification number; %, percent; OC, organic carbon; ND, not determined; RT, retention time; R1, result one; R2, result two; AD, average 

deviation, in percent; nd, not detected]
Table 16. Mean average deviation and range of average deviations for compounds detected in nine duplicate sediment samples and 

one triplicate sample extracted using accelerated solvent extraction.

[AD, average deviation; %, percent; ND, not determined]

Compound 

(retention time order) 

Mean 

AD1 (%)

Range 

AD1 (%)

Naphthalene 14 0 – 37

2-Ethylnaphthalene 17 17 – 17

2,6-Dimethylnaphthalene 19 6 – 30

1,6-Dimethylnaphthalene 27 11 – 45

Acenaphthylene 25 13 – 43

1,2-Dimethylnaphthalene 33 33 – 33

Acenaphthene 25 6 – 47

9H-Fluorene 12 3 – 21

Diethyl phthalate2 ND ND

1-Methyl-9H-fluorene 17 0 – 33

Dibenzothiophene 14 6 – 23

Phenanthrene 17 8 – 36

Anthracene 19 13 – 31

Phenanthridine 11 11 – 11

9H-Carbazole 10 1 – 22

2-Methylanthracene 19 6 – 25

Compound 

(retention time order) 

Mean 

AD1 (%)

Range 

AD1 (%)

4,5-Methylenephenanthrene 14 0 – 25

1-Methylphenanthrene 20 11 – 31

Anthraquinone 10 1 – 19

Fluoranthene 26 12 – 47

Pyrene 27 12 – 44

1-Methylpyrene 23 11 – 32

Benz[a]anthracene 14 0 – 29

Chrysene 18 2 – 35

Bis(2-ethylhexyl) phthalate 24 5 – 39

Benzo[b]fluoranthene 18 1 – 40

Benzo[k]fluoranthene 23 9 – 43

Benzo[e]pyrene 15 14 – 16

Benzo[a]pyrene 15 0 – 30

Perylene 7 5 – 9

Indeno[1,2,3-c,d]pyrene 17 6 – 27

Dibenz[a,h]anthracene 22 14 – 28

Benzo[g,h,i]perylene 15 5 – 22

1

The average deviation (AD), in percent, was calculated using equation 5 (Anderson, 1987).

2

Diethyl phthalate was only detected in one sample, so the average deviation could not be determined.

32  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Table 17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per kilogram, for 28 sediment samples.

[ID, identification number; %, percent; OC, organic carbon; SOX, Soxhlet; ASE, accelerated solvent extraction; RT, retention time; ND, not determined; nd, not 

detected; <, less than]

Compound (RT order)

Lab ID: 20022910084 20022950052 20031220119 20020450012 20013060058

Matrix / % OC: Clay / 3.2 Clay / 3.1 Core / ND Clay / ND Clay / 5.4

Method: SOX ASE SOX ASE SOX ASE SOX ASE SOX ASE

Naphthalene 13 13 21 16 10 21 4 nd 20 24

2-Ethylnaphthalene 3 6

2,6-Dimethylnaphthalene 35 31 80 49 150 157 126 58 158 154

1,6-Dimethylnaphthalene 15 10 19 14 18 33 22 20 18 51

Acenaphthylene <80 3 10 18 3 2 30 34

1,2-Dimethylnaphthalene 7 15

Acenaphthene 13 19

9H-Fluorene 15 19 22 24 46 38

Diethyl phthalate 2.3 8 12 nd

1-Methyl-9H-fluorene 5 nd 5 nd 7 12

Dibenzothiophene 17 6.5 35 24

Phenanthrene 22 21 34 35 123 83 45 40 460 326

Anthracene 15 7 24 12 34 32 7 8 110 85

Phenanthridine

9H-Carbazole 87 115

2-Methylanthracene 24 nd 10 20 4 nd 28 18

4,5-Methylenephenanthrene 10 9 20 37 11 8 115 88

1-Methylphenanthrene 12 nd 10 31 7 4 30 32

Anthraquinone nd 10 257 252

Fluoranthene 25 28 52 48 263 196 45 40 1,900 1,430

Pyrene 21 24 47 40 211 157 37 30 1,500 1,042

1-Methylpyrene 11 21 41 37

Benz[a]anthracene 10 9 21 12 116 98 15 14 561 363

Chrysene 11 19 27 23 131 135 19 26 1,030 794

Bis(2-ethylhexyl) phthalate 210 148 127 101 336 281

Benzo[b]fluoranthene 15 10 19 14 147 119 24 26 1,140 850

Benzo[k]fluoranthene 12 11 5 13 109 108 18 25 821 716

Benzo[e]pyrene 90 119 10 9

Benzo[a]pyrene 27 12 118 133 17 10 754 542

Perylene 467 658 902 630

Indeno[1,2,3-c,d]pyrene 132 155 22 24 704 710

Dibenz[a,h]anthracene 26 nd 3 2 140 163

Benzo[g,h,i]perylene 72 122 15 19 542 576

Analytical Method  33
Compound (RT order) 

Lab ID: 20013060057 20011930041 20031780065 20031780064 20022410090

Matrix / % OC: Clay / 6.4 Clay / 0.3 Soil / ND Soil / ND Silt / 13.3

Method: SOX ASE SOX ASE SOX ASE SOX ASE SOX ASE

Naphthalene 18 38 6 9 <500 66

2-Ethylnaphthalene

2,6-Dimethylnaphthalene 133 178 12 8 123 13 67 116 123 672

1,6-Dimethylnaphthalene 19 46 90 215

Acenaphthylene 21 40 30 39

1,2-Dimethylnaphthalene

Acenaphthene 12 37 25 26 <50 59

9H-Fluorene 49 47 44 43

Diethyl phthalate

1-Methyl-9H-fluorene 5 nd <50 6

Dibenzothiophene 32 36 29 33

Phenanthrene 587 579 724 688 <50 15 <50 22

Anthracene 99 120 111 135

Phenanthridine 16 18

9H-Carbazole 102 184 90 109

2-Methylanthracene 25 24 12 19

4,5-Methylenephenanthrene 120 119 86 92

1-Methylphenanthrene 33 46 30 38

Anthraquinone 280 423 230 232

Fluoranthene 1,970 1,945 1,400 1,585 <50 23 55 35

Pyrene 1,480 1,450 1,100 1,130 <50 20 <50 29

1-Methylpyrene 40 45 21 31

Benz[a]anthracene 504 508 444 443 <50 14 <50 18

Chrysene 1,000 1,115 730 685 <50 14 26

Bis(2-ethylhexyl) phthalate 301 293 118 83 321 167

Benzo[b]fluoranthene 1,050 1,170 684 660 <50 10 <50 18

Benzo[k]fluoranthene 898 818 566 538 <50 10 <50 20

Benzo[e]pyrene

Benzo[a]pyrene 702 678 566 443 <50 8 <50 22

Perylene

Indeno[1,2,3-c,d]pyrene 578 915 482 504 <50 17

Dibenz[a,h]anthracene 120 207 89 67 <50 7

Benzo[g,h,i]perylene 473 758 353 422 <50 13

Table 17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per kilogram, for 28 sediment samples.—

Continued

[ID, identification number; %, percent; OC, organic carbon; SOX, Soxhlet; ASE, accelerated solvent extraction; RT, retention time; ND, not determined; nd, not 

detected; <, less than]

34  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Compound (RT order)

Lab ID: 20013060059 20022560060 20022560059 20012560108 20022410092

Matrix / % OC: Clay / 3.0 Clay / 1.6 Clay / 0.9 Soil / 0.0 Silt / 24

Method: SOX ASE SOX ASE SOX ASE SOX ASE SOX ASE

Naphthalene 28 87 10 8 <50 5 <1,300 53

2-Ethylnaphthalene

2,6-Dimethylnaphthalene 142 120 242 249 32 35 1,290 907

1,6-Dimethylnaphthalene 23 42 28 49 11 13 323 373

Acenaphthylene 46 45

1,2-Dimethylnaphthalene

Acenaphthene 26 108

9H-Fluorene 51 122

Diethyl phthalate 6 7

1-Methyl-9H-fluorene 11 nd

Dibenzothiophene 36 59

Phenanthrene 608 1,330 25 16 9 7

Anthracene 144 263 21 15

Phenanthridine

9H-Carbazole 100 250

2-Methylanthracene 29 51

4,5-Methylenephenanthrene 111 193

1-Methylphenanthrene 49 87

Anthraquinone 266 433

Fluoranthene 1,740 2,590 29 27 13 14 1 13

Pyrene 1,320 1,890 23 26 9 12 <50 10

1-Methylpyrene 49 63

Benz[a]anthracene 590 835 17 20 <50 8

Chrysene 958 1,420 8 23 <50 13

Bis(2-ethylhexyl) phthalate 660 489 382 110 39 48 59 29 972 204

Benzo[b]fluoranthene 1,150 1,000 17 30 <50 15

Benzo[k]fluoranthene 740 1,080 14 36 <50 14

Benzo[e]pyrene

Benzo[a]pyrene 720 804 29 34 <50 14

Perylene

Indeno[1,2,3-c,d]pyrene 640 948 <50 18

Dibenz[a,h]anthracene 144 260

Benzo[g,h,i]perylene 482 790 <50 18

Analytical Method  35

Table 17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per kilogram, for 28 sediment samples.—

Continued

[ID, identification number; %, percent; OC, organic carbon; SOX, Soxhlet; ASE, accelerated solvent extraction; RT, retention time; ND, not determined; nd, not 

detected; <, less than]
Compound (RT order)

Lab ID: 20031780069 20031780070 20020630040 20022970068 20012480191

Matrix / % OC: Soil / ND Soil / ND Clay / ND Clay / 3.4 Soil / ND

Method: SOX ASE SOX ASE SOX ASE SOX ASE SOX1 ASE1

Naphthalene 28 43 <100 21 263 1,560

2-Ethylnaphthalene 8 9 35 88

2,6-Dimethylnaphthalene 87 13 29 23 158 168 85 112

1,6-Dimethylnaphthalene 33 33 24 35 75 127

Acenaphthylene <50 32 884 3,250

1,2-Dimethylnaphthalene 14 10 33 53

Acenaphthene 1,580 3,000

9H-Fluorene 6 6 2,130 4,480

Diethyl phthalate 14 18

1-Methyl-9H-fluorene 6 6 244 387

Dibenzothiophene

Phenanthrene 36 52 12 15 46,400 96,000

Anthracene 3 5 6,650 12,000

Phenanthridine

9H-Carbazole

2-Methylanthracene 3 3 1,040 1,690

4,5-Methylenephenanthrene 2 nd 6,020 11,000

1-Methylphenanthrene 14 19 2,210 5,300

Anthraquinone

Fluoranthene 13 24 20 19 131,000 293,000

Pyrene 14 24 23 20 106,000 228,000

1-Methylpyrene 10 8 2,860 5,620

Benz[a]anthracene 9 17 <100 11 49,500 98,000

Chrysene 15 27 <100 18 81,300 180,000

Bis(2-ethylhexyl) phthalate <300 52

Benzo[b]fluoranthene 12 19 <100 68 76,200 175,000

Benzo[k]fluoranthene 7 16 <100 71 60,300 133,000

Benzo[e]pyrene 12 19 44,200 118,000

Benzo[a]pyrene 10 10 27 59 62,500 135,000

Perylene 52 47 15,000 35,000

Indeno[1,2,3-c,d]pyrene 8 15 75,600 148,000

Dibenz[a,h]anthracene 12,900 30,000

Benzo[g,h,i]perylene 16 28 48,200 120,000

36 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids

Table 17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per kilogram, for 28 sediment samples.—

Continued

[ID, identification number; %, percent; OC, organic carbon; SOX, Soxhlet; ASE, accelerated solvent extraction; RT, retention time; ND, not determined; nd, not 

detected; <, less than]
Compound (RT order) 

Lab ID: 20012480193 20030940075 20031220109 20031220117 20031220120

Matrix / % OC: Soil / ND Silt / ND Core / ND Core / ND Core / ND

Method: SOX1 ASE1 SOX ASE SOX ASE SOX ASE SOX ASE

Naphthalene 83 254 159 197 8 26 14 46 5 20

2-Ethylnaphthalene 14 28 31 27 2 nd 2 nd 

2,6-Dimethylnaphthalene 33 46 164 81 2 6 92 97 86 86

1,6-Dimethylnaphthalene 28 51 59 55 13 17 12 30 10 18

Acenaphthylene 292 670 245 287 12 28 14 30 11 21

1,2-Dimethylnaphthalene 11 nd 33 21 7 20 7 18 3 nd 

Acenaphthene 538 588 747 504 21 23 12 28 14 25

9H-Fluorene 710 865 1,180 820 26 30 27 90 16 24

Diethyl phthalate

1-Methyl-9H-fluorene 150 98 129 90 6 nd 6 15 4 nd 

Dibenzothiophene

Phenanthrene 15,800 19,600 12,400 10,200 240 240 312 741 200 222

Anthracene 2,490 3,250 1,200 980 62 63 70 190 47 56

Phenanthridine

9H-Carbazole

2-Methylanthracene 393 454 222 215 14 30 14 42 12 20

4,5-Methylenephenanthrene 2,150 2,990 1,380 1,250 42 61 44 115 35 56

1-Methylphenanthrene 821 1,180 612 514 16 19 17 51 16 31

Anthraquinone

Fluoranthene 50,200 68,000 21,100 20,000 508 494 653 1,100 633 614

Pyrene 40,700 54,000 14,800 13,500 431 390 492 850 502 476

1-Methylpyrene 1,100 3,460 553 585 21 37 22 49 20 34

Benz[a]anthracene 19,700 24,000 6,220 6,000 240 185 265 402 267 226

Chrysene 3,100 41,000 10,600 12,000 254 242 290 478 296 292

Bis(2-ethylhexyl) phthalate

Benzo[b]fluoranthene 29,000 38,000 9,170 10,300 254 219 290 394 354 326

Benzo[k]fluoranthene 23,800 28,000 7,300 7,700 226 183 259 374 279 308

Benzo[e]pyrene 17,500 26,500 6,540 7,100 162 158 187 296 190 197

Benzo[a]pyrene 25,000 30,600 7,130 7,400 230 185 259 352 281 234

Perylene 6,220 8,300 1,790 3,600 344 356 217 323 447 530

Indeno[1,2,3-c,d]pyrene 29,300 33,600 6,890 5,880 227 170 150 260 288 221

Dibenz[a,h]anthracene 5,020 5,860 1,140 1,540 54 65 67 130 58 49

Benzo[g,h,i]perylene 20,000 28,500 5,930 4,040 134 154 150 260 152 189

Analytical Method  37

Table 17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per kilogram, for 28 sediment samples.—

Continued

[ID, identification number; %, percent; OC, organic carbon; SOX, Soxhlet; ASE, accelerated solvent extraction; RT, retention time; ND, not determined; nd, not 

detected; <, less than]
Compound (RT order)

Lab ID: 20031200121 20031220186 20020450009

Matrix / % OC: Core / ND Core / ND Clay / ND

Method: SOX ASE SOX ASE SOX ASE

Naphthalene 7 14 8 430 2 3

2-Ethylnaphthalene 4 8 3 256

2,6-Dimethylnaphthalene 89 65 174 409 49 31

1,6-Dimethylnaphthalene 17 20 20 210 11 6

Acenaphthylene 11 19 12 131

1,2-Dimethylnaphthalene 7 13 6 152 4 nd

Acenaphthene 20 135

9H-Fluorene 8 14 21 96 3 7

Diethyl phthalate

1-Methyl-9H-fluorene 4 nd 6 37

Dibenzothiophene

Phenanthrene 68 71 220 199 12 15

Anthracene 23 36 56 69 2 3

Phenanthridine

9H-Carbazole

2-Methylanthracene 7 nd 14 23 3 nd

4,5-Methylenephenanthrene 14 30 36 58 4 4

1-Methylphenanthrene 6 nd 16 25 2 nd

Anthraquinone

Fluoranthene 198 177 520 408 11 16

Pyrene 153 143 409 327 6 10

1-Methylpyrene 9 nd 19 35

Benz[a]anthracene 81 66 225 168 4 4

Chrysene 104 100 227 217 6 10

Bis(2-ethylhexyl) phthalate

Benzo[b]fluoranthene 112 94 275 196 9 8

Benzo[k]fluoranthene 91 95 175 185 4 6

Benzo[e]pyrene 84 83 159 138 3 5

Benzo[a]pyrene 97 85 209 176 5 4

Perylene 317 360 515 600 165 206

Indeno[1,2,3-c,d]pyrene 62 65 205 168 4 nd

Dibenz[a,h]anthracene 41 55

Benzo[g,h,i]perylene 61 82 114 140 2 nd

1

Sample extracts required significant dilutions.

38  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids

Table 17. Soxhlet and accelerated solvent extraction concentrations, in micrograms per kilogram, for 28 sediment samples.—

Continued

[ID, identification number; %, percent; OC, organic carbon; SOX, Soxhlet; ASE, accelerated solvent extraction; RT, retention time; ND, not determined; nd, not 

detected; <, less than]
Table 18. Correlation of Soxhlet and accelerated solvent extraction results for 28 sediment samples.

[Ave, average; μg/kg, micrograms per kilogram; SOX, Soxhlet; ASE, accelerated solvent extraction; r2, correlation coefficient; m, slope; b, intercept; N, total 

number of detection pairs if detected by both the ASE and Soxhlet method; NPE, number of points excluded]

Compound Ave SOX 

(μg/kg)

Ave ASE 

(μg/kg) r

2 m b N NPE*

Naphthalene 21 69 0.827 1.4304 19 20 2

2-Ethylnaphthalene 11 28 0.832 1.8494 -2 7 1

2,6-Dimethylnaphthalene 145 155 0.801 0.6956 54 26 0

1,6-Dimethylnaphthalene 40 67 0.862 1.1617 20 22 0

Acenaphthylene 37 52 0.912 1.0808 18 14 2

1,2-Dimethylnaphthalene 13 19 0.651 0.8834 6 9 1

Acenaphthene 273 379 0.949 1.6687 -48 11 0

2,3,6-Trimethylnaphthalene 32 36 0.997 1.2188 -6 5 0

9H-Fluorene 272 396 0.938 1.7704 -62 16 0

Diethyl phthalate 8 4 0.278 0.3835 5 4 0

1-Methyl-9H-fluorene 42 72 0.908 1.2694 -8 8 0

Dibenzothiophene 30 32 0.764 1.8957 -25 5 0

Phenanthrene 1,597 1,569 0.979 1.0824 -4 21 1

Anthracene 588 912 0.992 1.7408 -111 19 0

9H-Carbazole 95 164 0.827 7.5696 -552 4 0

2-Methylanthracene 109 186 0.991 1.5710 -20 14 0

4,5-Methylenephenanthrene 261 341 0.981 1.2546 -9 16 1

1-Methylphenanthrene 106 148 0.967 1.2239 1 15 1

Anthraquinone 258 335 0.835 4.2777 -770 4 0

Fluoranthene 3,698 4,297 0.993 1.3012 -321 23 1

Pyrene 3,164 3,287 0.994 1.2871 -295 23 1

1-Methylpyrene 68 86 0.999 1.0401 9 13 2

Benz[a]anthracene 1,627 1,519 0.998 1.2017 -101 18 1

Chrysene 2,600 2,667 0.999 1.3040 -135 19 1

Bis(2-ethylhexyl) phthalate 255 164 0.888 0.6716 3 11 1

Benzo[b]fluoranthene 2,429 2,434 0.999 1.3004 -190 19 1

Benzo[k]fluoranthene 1,962 1,833 0.999 1.1689 -60 19 1

Benzo[e]pyrene 2,267 3,148 0.995 1.4758 -198 11 1

Benzo[a]pyrene 2,010 1,991 0.966 0.8969 8 17 3

Perylene 1,040 1,419 0.986 1.3714 -7 12 1

Indeno[1,2,3-c,d]pyrene 2,646 2,569 0.998 1.1361 -104 15 1

Dibenzo[a,h]anthracene 575 647 0.999 1.1701 27 12 1

Benzo[g,h,i]perylene 1,900 2,124 0.988 1.3801 -232 15 1

*

Data point(s) were excluded from the correlation calculation because of possible dilution errors that might have resulted in significantly higher ASE concentrations than Soxhlet concentrations.

Analytical Method  39
Figure 3. Least squares regression plots for concentrations 

of naphthalene (A) and benzo[a]pyrene (B) determined in 

28 sediment samples by accelerated solvent extraction (ASE) 

and by Soxhlet extraction.

0

50

100

150

200

250

300

0 50 100 150 200

SOXHLET (IN MICROGRAMS PER KILOGRAM)

ASE (IN MICROGRAMS

PER KILOGRAM)

SOXHLET (IN MICROGRAMS PER KILOGRAM)

ASE (IN MICROGRAMS

PER KILOGRAM)

0

200

400

600

800

1,000

0 200 400 600 800

A

B

Y = 1.43 X + 19

Y = 0.897 X + 8

The average compound concentrations, slopes, and 

intercepts have been listed (table 18) to help compare the two 

methods. The average compound concentration recoveries 

using ASE generally are somewhat higher than by Soxhlet. 

A few very high concentrations, which required large extract 

dilutions (and possibly subject to dilution errors), were 

excluded from statistical calculations for some compounds (as 

footnoted in table 18) because least squares linear regression 

curves were excessively weighted toward the high measurements, thereby causing distorted average concentrations, 

slopes, and intercepts. Incidentally, all of the high concentrations that were excluded from the calculations were much 

higher by ASE than by Soxhlet extraction. For the more polar 

compounds, the average extraction efficiency generally is 

greater using ASE, as might be expected based on increased 

solubility in the more polar isopropyl alcohol/water extraction solvent. A few compounds (diethyl phthalate, 9H-carbazole, and anthraquinone) were only detected four times each 

(table 17), and thus, lack the necessary data to make meaningful correlations.

 As was demonstrated with SRM 1944 (table 13), extraction of lower molecular weight PAH compounds, such as 

naphthalene and phenanthrene, from a variety of sediments 

also was more efficient by ASE than by Soxhlet, possibly 

because of increased solvent penetration from increased swelling of clay particles (Hawthorne, Trembley, and others, 2000). 

As the solubility of the PAHs in the hot isopropyl alcohol/

water solvent mixture decreases (about the molecular weight 

of fluoranthene or higher), the correlation between the two 

methods is much better. This general trend of improved correlation with greater PAH molecular weight is shown in figure 3 

for naphthalene and benzo[a]pyrene.

Figure 4 shows a boxplot for the ASE extraction results 

of 28 environmental sediment samples collected from throughout the United States. The samples are a mixture of soil, 

stream sediment, and suspended sediment, with the majority from urban sampling sites. The data are reported using a 

log scale to accommodate the large concentration ranges for 

each compound. At least one method compound was found 

in every environmental sample analyzed. Thirty-four compounds (excluding alkylated PAH homolog groups) were 

detected in at least one sample with concentrations ranging 

from 20 to 100,000 μg/kg. The most frequently detected 

compound, 2,6-dimethylnaphthalene, was detected in 23 of 

the 28 (82.1 percent) environmental samples with a concentration range of 15 to 907 μg/kg. At least one of the PAH 

homolog compounds was detected in 26 of the 28 samples 

(92.9 percent) with C2-alkylated naphthalenes being detected 

in 26 samples. Thirteen out of 25 of the homolog groups 

(52 percent) were detected with concentrations ranging from 

20 to 10,000 μg/kg. The C1-alkylated PAHs accounted for 71 

of the 185 (38.4 percent) alkylated PAH detections, whereas 

the C2-alkylated and C3-alkylated groups accounted for 35.1 

and 22.2 percent of the detections, respectively. There were 

no detections greater than the minimum reporting level for C4- 

and C5-alkylated homolog groups. The absence of detections 

for the C4- and C5-alkylated homolog groups at or greater than 

the minimum reporting level also was observed for the NIST 

1944 SRM. These results (concentration ranges and detection 

frequencies) demonstrate the usefulness of this method for 

determining the compound classes of interest in various sediment and soil types.

Summary and Conclusions

This report presents a method (U.S. Geological Survey National Water Quality Laboratory analytical method 

O-5506-06) for extracting environmental sediment samples 

with a commercially available Dionex ASETM 200 instrument 

using accelerated solvent extraction (ASE). Water modified 

with isopropyl alcohol is used as the extraction solvent at 

elevated temperatures and pressure for the determination of 

38 polycyclic aromatic hydrocarbons (PAHs) and semivolatile 

organic compounds with an additional option to report the 

semiquantitation of 25 alkylated PAH homolog groups, by gas 

chromatography/mass spectrometry. The concentrations of 

the alkylated PAH homolog groups are reported as estimated 

because of the lack of authentic standards.

This ASE method of sediment sample preparation has 

advantages over conventional Soxhlet extraction for sample 

automation, reduced extraction time, and reduced solvent 

volume. Sample preparation also is simplified over Soxhlet 

extraction with dichloromethane (DCM) because the ASE 

water/isopropyl alcohol extract is well suited for solid-phase 

extraction (SPE) extract cleanup, whereas DCM Soxhlet 

40 Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
5

50

500

5,000

Naphthalene (15)

2-Ethylnaphthalene (4)

2,6-Dimethylnaphthalene (23)

1,6-Dimethylnapthalene (15)

Acenaphthylene (12)

1,2-Dimethylnaphthalene (4)

Acenaphthene (11)

2,3,6-Trimethylnaphthalene (3)

9H-Fluorene (12)

1-Methyl-9H-fluorene (4)

Dibenzothiophene (4)

Phenanthrene (17)

Anthracene (13)

Acridine (4)

Phenanthridine (1)

9H-Carbazole (4)

2-Methylanthracene (8)

4,5-Methylenephenanthrene (13)

1-Methylphenanthrene (12)

Anthraquinone (4)

Fluoranthene (18)

Pyrene (19)

1-Methylpyrene (11)

Benz[a]anthracene (14)

Chrysene (18)

Bis-(2-ethylhexyl) phthalate (12)

Benzo[b]fluoranthene (17)

Benzo[k]fluoranthene (16)

Benzo[e]pyrene (9)

Benzo[a

Perylene (12)

]pyrene (16)

Indeno[1,2,3-c,d]pyrene (14)

Dibenzo[a,h]anthracene (11)

Benzo[g,h,i]perylene (14)

C1-Alkylated naphthalene (19)C2-Alkylated naphthalene (26)C3-Alkylated naphthalene (20)

C1-Alkylated phenanthrene/anthracene (16)C2-Alkylated phenanthrene/anthracene (15)C3-Alkylated phenanthrene/anthracene (11)

C1-Alkylated fluoranthene/pyrene (15)C2-Alkylated fluoranthene/pyrene (12)C3-Alkylated fluoranthene/pyrene (10)

C1-Alkylated benzo[a]anthracene/chrysene (12)C2-Alkylated benzo[a]anthracene/chrysene (12)

C1-Alkylated benzopyrene/perylene (10)

C2-Alkylated benzopyrene/perylene (7)

50th percentile

75th percentile

90th percentile

25th percentile

10th percentile

EXPLANATION

Data point

50,000

500,000

CONCENTRATION, IN MICROGRAMS PER KILOGRAM

Figure 4. Results for analysis of 28 environmental soil and sediment samples. The concentration axis is 

in log scale to accommodate the large concentration ranges for the compounds of interest. The number 

of samples in which the compound was detected is listed after each compound name in parenthesis. Data 

points that are shown are outliers of the distribution.

Summary and Conclusions  41
extracts usually require a more complex gel permeation chromatography clean-up step.

The performance of the method (mean recovery and bias) 

was determined using Ottawa sand, a commercially available 

topsoil, and an environmental stream sediment, fortified at 

1.5 and 15 micrograms per compound. The recoveries of PAH 

and semivolatile organic compounds from a 22-milliliter ASE 

cell filled with Ottawa sand (about 25 grams) fortified at 1.5 

microgram per compound averaged 88 percent ± 9.4 percent 

relative standard deviation, and calculated initial method 

detection limits averaged 14 micrograms per kilogram (assuming a 25-gram sample size).

A National Institute of Standards and Technology certified natural marine sediment reference material (SRM 1944) 

was used to compare this ASE method with conventional 

36-hour Soxhlet extraction using DCM. The recovery of low 

molecular weight PAH compounds (for example, naphthalene, 

phenanthrene, and anthracene) was greater by 10 to 20 percent 

using this ASE method compared to certified concentrations 

obtained by Soxhlet extraction. The recoveries for higher 

molecular weight PAH compounds were somewhat less than 

certified concentrations, but were identical to those obtained 

by the U.S. Geological Survey (USGS) Soxhlet extraction 

method. Method precision for the certified PAH compounds 

was between about 7 to 15 percent relative standard deviation 

in the reference material. Although absolute concentrations of 

alkylated PAH homolog groups in the reference material were 

not certified, their recoveries were similar to those obtained by 

the USGS Soxhlet extraction method, and precision was less 

than 12 percent relative standard deviation.

Replicate sample results for a diverse group of 28 environmental sediments also were used to compare ASE extraction with the existing USGS Soxhlet extraction. The same 

recovery trends for PAHs observed for SRM 1944 also were 

manifest in the sediment samples because compound correlations improved with increasing PAH molecular weight. The 

average compound concentration recoveries, slopes, and intercepts also were listed to help compare the two methods. The 

average extraction efficiency for the more polar compounds 

was greater using this ASE method, as might be expected 

based on increased solubility in the more polar isopropyl alcohol/water solvent.

The extraction of solids using this ASE method for the 

determination of PAHs and semivolatile compounds will augment other methods at the National Water Quality Laboratory 

to better understand their presence, fate, transport, and temporal and spatial distribution in the environment.

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Manuscript approved for publication April 2006

Prepared by the Publishing Group, U.S. Geological Survey, 

National Water Quality Laboratory, Denver, Colorado.

USGS Publishing Staff

Edited by Jon W. Raese

Report approved by Keith L. Lucey

Cover designed by Suzanne C. Roberts

Report prepared by Suzanne C. Roberts

Technical Reviews

Jeffrey N. Morgan, U.S. Environmental Protection Agency

Peter C. Van Metre, USGS, Texas Water Science Center

Peter F. Rogerson, USGS, Office of Water Quality

Edward T. Furlong, USGS, National Water Quality Laboratory

James A. Lewis, USGS, National Water Quality Laboratory

For more information concerning the research in this report, contact:

National Water Quality Laboratory, Chief

U.S. Geological Survey 

P.O. Box 25046, MS 407 

Denver Federal Center

Denver, Colorado 80225-0046 

http://nwql.cr.usgs.gov

Glossary

Continuing calibration verification (CCV) A standard solution that contains method compounds and is used to determine 

the bias of the present calibration curve for the method compounds. The CCV is an instrumental standard only and is not 

processed through preparative steps of the method.

Internal standard (IS) A compound not expected to be found 

in any environmental sample that is added to every sample 

extract in a known amount. The internal standard is used to 

measure the relative gas chromatographic/mass spectrometric 

(GC/MS) responses of other compounds and surrogates in 

each sample.

Long-term method detection level (LT–MDL) The minimum 

concentration of a substance that can be identified, measured, 

and reported with 99-percent confidence that the compound 

concentration is greater than zero. The LT–MDL is calculated from replicate analyses of samples fortified with all the 

method compounds, and includes precision introduced by 

multiple instruments, multiple analysts, and multiple calibrations from 6 to 12 months (Childress and others, 1999).

Method detection limit (MDL) The minimum concentration 

of a substance that can be measured and reported with 99-

percent confidence that the compound concentration is greater 

than zero (U.S. Environmental Protection Agency, 1997). The 

MDL is calculated from at least seven replicate analyses of 

samples fortified with all the method compounds. The MDL 

is used to establish initial method reporting levels, until the 

long-term method detection level can be calculated to include 

day-to-day precision.

Minimum reporting level (MRL) The lowest measured 

concentration of a compound that may be reliably reported by 

using a given analytical method (Timme, 1995).

Surrogate A compound not expected to be found in any 

environmental sample that is added to every sample in a 

known amount prior to sample processing. The surrogate is 

used to monitor method performance for each sample.

44  Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids
Zaugg and others—Determination of Semivolatile Organic Compounds and Polycyclic Aromatic Hydrocarbons in Solids—Techniques and Methods 5–B3

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