515.4-1

METHOD 515.4 DETERMINATION OF CHLORINATED ACIDS IN DRINKING

WATER BY LIQUID-LIQUID MICROEXTRACTION, DERIVATIZATION, A ND FAST GAS CHROM ATOGRAPHY WITH ELECTRON CAPTURE D ETECTION

Revision 1.0 April 2000

S.C. Wendelken, M.V. Bassett, T.A. Dattilio, and B.V. Pepich (IT Corporation) D.J. Munch (US EPA, Office of Ground Water and Drinking Water) - Method 515.4, Revision 1.0 (2000) A. M. Pawlecki-Vonderheide (ICI) and D.J. Munch (US EPA, Office of Ground Water and Drinking Water) - Method 515.3, Revision 1.0 (1996) J.W. Hodgeson - Method 515.2, Revision 1.0 (1992) R.L. Graves - Method 515.1, Revision 4.0 (1989) T. Engels (Batelle Columbus Laboratory ) and D.J. Munch (US EPA, Office of Ground Water and Drinking Water) - National Pesticide Survey Method 3, Revision 3.0 (1987) J.W. Hodgeson - Method 515, Revision 2.0 (1986)

TECHNICAL SUPPORT CENTER OFFICE OF GROUND WATER AND DRINKI NG WATER U. S. ENVIRONM

ENTAL PROTECTI

ON AGENCY CINCINNATI, OHI

O 45268515.4-2

METHOD 515.4 DETERMINATION OF CHLORINATED ACIDS IN DRINKING

WATER BY LIQUID-LIQUID MICROEXTRACTION, DERIVATIZATION, A ND FAST GAS CHROM ATOGRAPHY WITH ELECTRON CAPTURE D ETECTION
1. SCOPE AND APP LICATION
1.1 This is a fast gas chromatography (GC) method for the de termination of chlorinated acids in drinking waters. Accuracy, prec ision, and Detection Limit data have been generated for the following compounds in reagent water and f inished ground and surface water

s. Analyte Chemical Abstracts Service Registry Number Acifluorfen(a) 50594-66-6 Bentazon 25057-89-0 Chloramben 133-90-4 2,4-D 94-75-7 Dalapon 75-99-0 2,4-DB 94-82-6 Dacthal acid metabolites (b) Dicamba 1918-00-9 3,5-Dichloroben

zoic acid 51-36-5 Dichlorprop 120-36-5 Dinoseb 88-85-7 Pentachlorophenol 87-86-5 Picloram 1918-02-1 2,4,5-T 93-76-5 2,4,5-TP (Silvex) 93-72-1 Quinclorac 84087-01-4 (a) The herbicide L

actofen will be qu

antitated as Acif

luorfen as their structures represent different esters of the same acid herbicide. (b) Dacthal mono-acid and di-acid metabolites are included in method scope; Dacthal d

i-acid was used f

or validation studie

s.515.4-3

1.2 This method is also a pplicable to the de

termination of sal

ts and esters of a

nalyte acids. The form of each acid is not distinguished by this method. Results are calculated and r

eported for eac

h listed analy

te as the total fre

e acid. This method

is able to quantify the mono- and di-acid forms of Dacthal but not the parent compound.

1.3 Detection Limits are compound, instrument, and matrix dependent. The Detection Limit is defined as the statistically calculated minimum amount that can be measured with 99% confidence that the reported value is greater than zero.(1) Experimentally determined Detection Limits for the above listed analytes ar e provided in Section 17, Table 4. The Detection Limit differs from, and is usually lower than (but never above), the minimum r eporting le vel (MRL) (Sec t. 3.17). T he concentra tion range for target analytes in this method was evaluated between 0.5 ug /L and 20 ug/L for a 40-mL sample. Precision and accuracy data are presented in Section 17, Tables 5 - 10.
1.4 This method is restr icted to use by

or under the supe

rvision of analy

sts skilled in liquid-liquid extractions, derivatization procedures and the use of GC and interpretation of gas chromatograms. The method was developed using fast GC but “conventional” GC may be used as long as the laboratory meets the requirements of the IDC (Sect. 9.2).
2. SUMMARY OF METHO D
2.1 A 40-mL volume of sample is adjusted to pH $ 12 with 4 N sodium hydroxide and allowed to sit for one hour at room temperature to hydroly ze derivatives. Following hydroly sis, a wash step usin

g a hexane:MtBE

mixture is performe

d as a sample cleanup and to re

move Dacthal. The

aqueous sample is t

hen acidified wit

h sulfuric acid to a pH of less than 1 and extracted with 4-mL of methyl tert-buty l ether (MtBE). The chlorinated

acids that have be

en partitioned into

the MtBE are the

n converted to methyl esters by derivatization with diazomethane. The targ et esters are separated and identified by fast capillary c olumn gas chromatography using an elec tron capture detector (GC/ECD). Analytes are quantified using a proce dural standard calibration technique with an internal standard. NOTE: since many of the analyte s contained in this method are applied as a variety of esters and salts,

it is imperative to hy

drolyze them

to the parent aci

d prior to extraction.
3. DEFINITIONS
3.1 EXTRACTION BATCH – A set of up to 20 field samples (not including QC515.4-4 samples) extracte

d together by

the same person(

s) during a work

day using t

he same lots of solvents, surrogate solution, and fortifying solutions. Required QC samples include Labo

ratory Rea

gent Blank, L

aboratory Fortified Matrix, a

nd either a Field Duplicate or Laboratory Fortifie d Matrix Duplicate.
3.2 ANALYSIS BATCH – A set of samples that is analy zed on the same instrument during a 24-hour

period that beg

ins and ends with the

analysis of

the appropriate Continuing Calibration Check standards (CCC). Additional CCCs may be required depending on the

length of the an

alysis batc

h and/or the numbe

r of Field Samples

. 3.3 INTERNAL STANDARD (IS) – A pure analyte added to an extract or standard solution in a known amount and used to measure the relative responses of other method analy

tes and surroga

tes. The internal

standard must be a

n analyte th

at is not a sample component.
3.4 SURROGATE ANALYTE (SUR) – A pure analyte, which is e xtremely unlikely to be found in any sample, and which is added to a sample aliquot in a known amount before extraction or other processing, and is measured with the same procedures used to measure other sample components. The purpose of the SUR is to monitor method performance with each sample.
3.5 LABORATORY REAGENT BLANK (L RB) – An aliquot of reagent water or other blank matrix that is treated exactly as a sample including exposure to all glassware, equipment, solvents, reagents, sample preservatives, internal standards, and surrogates that are used in the extraction batch. The LRB is used to determine if method analytes or

other interfere

nces are prese

nt in the laborator

y environme

nt, the reagen

ts, or the apparatus

. 3.6 LABORATORY FORTIFI ED BLANK (LFB) – An aliquot of re agent water or other blank matrix to which known quantities of the method analytes and all the preservation compounds are added. The LFB is analy zed exactly like a sample, and its purpose is to determine whether the methodology is in control, and whether the laboratory

is capable of mak

ing accurate

and precise mea

surements.
3.7 LABORATORY FORTIFI ED SAMPLE MATRIX (LFM) – An aliquot of an environmental sample to which known quantities of the method analytes and all the preservation co

mpounds are adde

d in the laborator

y. The L FM is analyze

d exactly like a sample, and its purpose is to determine whether the sample matrix contributes bias to the analytical results. The background concentrations of the a nalytes in the sample matrix must be d

etermined in a se

parate aliquot a

nd the measured v

alues in the LFM corr

ected for back

ground concen

trations.
3.8 LABORATORY FORTIFI ED SAMPLE MATRIX DUPLI CATE (LFMD) – A515.4-5 second aliquot of the Field Sample used to prepare the LFM which is fortified, extracted and ana

lyzed identic

ally. The L

FMD is used instea

d of the Field Dupl

icate to access method p

recision and acc

uracy whe

n the occurrenc

e of target ana

lytes is low.
3.9 LABORATORY D UPLICATES

(LD1 and L

D2) – Two aliquots o

f the same sample taken in the laboratory and analy zed separately with identical procedures. Analy ses of LD1 and LD

2 indicate preci

sion associated w

ith laboratory

procedures, but

not with sample collection

, preservation, a

nd storage proc

edures.
3.10 FIELD D

UPLICATES

(FD1 and FD2) –

Two separate sa

mples collected a

t the same time and place under identical circumstances, and treated exactly the sa me throughout field and laboratory procedures. Analy ses of FD1 and FD2 give a measure of the precision associ

ated with sample c

ollection, prese

rvation, and stora

ge, as well as w

ith laboratory

procedures.
3.11 STOCK STANDARD SOLUTION (SSS) – A concentrated solution containing one or more method ana

lytes prepa

red in the labora

tory using a

ssayed ref erence materi

als or purchased from a reputable commercial source.
3.12 PRIMARY DILUTI ON STANDARD SOLUTION (PDS) – A solution containing method analytes prepared in the laboratory from stock standard solutions and diluted as needed to pre

pare calibratio

n solutions and other

needed analy

te solutions.
3.13 CALIBRATION STANDARD ( CAL) – A solution prepared from the primary dilution standard solution or stock standard solutions and the internal standards and surrogate ana

lytes. The CA

L solutions are

used to calibrate

the instrument res

ponse with respect to analyte concentration.
3.14 CONTINUING CALI BRATION CHECK (CCC) – A calibration standard containing one or more method analytes, which is analy zed periodically to verify the acc uracy of the existing calibration for those analytes.
3.15 QUALITY CONTROL SAMPL E (QCS) – A solution of method analytes of known concentrations that is obtained from a source external to the laboratory and diffe rent fro m th e so urce of ca lib rat ion sta nda rds . It i s us ed t o ch eck s tan dard int egri ty.
3.16 DETECTION LIMI T – The minimum concentration of an analyte that can be identified, measured and reported with 99% confidence that the analy te concentration is greater than zero (Section 9.2.4). This is a statistical determination of precision. Accurate quant

itation is not expecte

d at this level. (1)
3.17 MINIMUM REPORTING L EVEL (MRL) – The minimum concentration that can be515.4-6 reported as a qu

antified value f

or a target ana

lyte in a samp

le following ana

lysis. This defined concentration can be no lower than the concentration of the lowest continuing calibration standard for that analyte, and can only be used if acceptable quality control criteria for thi

s standard are me

t.
3.18 PROCEDURAL STANDARD CALIBRATI ON – A calibration method where aqueous calibration standards are prepared and processed (e.g., purged, extracted, and/or derivatize

d) in exactly

the same manner a

s a sample. All steps in the process from addition of sa

mpling preserva

tives through inst

rumental analy

ses are included

in the calibration. Using procedural standard calibration compensates for any inefficiencies in the processing procedure.
3.19 MATERIAL SAFETY DATA SHEET (MSDS) – Written information provided by vendors concerning a chemical’s toxicity, health hazards, phy sical properties, fire, and reactivity data including st

orage, spill, an

d handling prec

autions.
4. INTERFERENCES
4.1 All glassware must be meticulously cleaned. Wash glassware with dete rgent and tap water, rinse with

tap water, follow

ed by reag

ent water. A fina

l rinse with solvent

s may be needed. In place of a solvent rinse, non-volumetric glassware can be muffled at 400 o C for 2 hours. Volumetric glassware should not be heated in an oven above 120 o C. Store inverted o

r capped with alu

minum foil.
4.2 Method interferences may be caused by contaminants in solvents, reagents (including reagent water), sample bottles and caps, and other sample processing har dware that lead to discrete

artifacts and/or

elevated baseli

nes in the chromat

ograms. All items such as these must be routinely demonstrated to be free from interfere nces (less than 1 /3 the MRL for each target) under the conditions of the analy sis by analyzing laboratory reagent blanks as described in Section 9. Subtracting blank values from sample results is not permitted. 4.2.1 During meth

od development it w

as found that sodium

sulfate from seve

ral sources containe

d multiple interfe

rences. After

screening sev

eral brands, it was found that a g

rade suitable fo

r pesticide resid

ue analysis

provided the best results. If the suitability of the available sodium sulfate is in question, extract and analyze a laboratory r eagent blank (section 3.5) to test for interferences prior to sa mple proces sing.
4.3 Matrix interferences may be caused by contaminants that are extracted from the sample. The extent o

f matrix interfere

nces will vary

considerably

from source to source, depending upon the water sampled.515.4-7 4.3.1 During method development a contaminant was found in local ground water and surface water that interfered with the analy sis of Dalapon on the primary column. Due to this interferent, it was necessary to carefully optimize the chromatographic conditions (see Table 1). A slow initial temperature program was needed to en

sure separation

of the interfere

nt from Dalapon. A

nalyte identifications should be confirmed using the confirmation column specified in Table 2 or another column that is dissimilar to the primary column or by GC/MS if the concen

trations are suff

icient.
4.4 Interferences by phthalate esters can pose a major problem in pesticide analysis when using an electron capture detector (ECD). These compounds genera lly appear in the chromatogram as large peaks. Common flexible plastics contain varying amounts of phthalates that a

re easily e

xtracted or leac

hed during labor

atory oper

ations. Cross contamination of clean glassware routinely occurs whe n plastics are handled during extraction steps, especially when solvent-wetted surfaces are handle d. Interferences from phthalates can best be minimized by avoiding the use of plastics in the laboratory

. Exhaustive purific

ation of reage

nts and glasswar

e may be re

quired to eliminate background phthalate contamination. (2,3)
5. SAFETY
5.1 The toxicity or carcinogenicity of e ach reagent used in this method has not been precisely defined. Each c

hemical compound s

hould be treated a

s a potential heal

th hazard, and exposur

e to these chemic

als should be minimize

d. The laborator

y is responsible for maintaining a current awareness file of OSHA regulations reg arding the safe handling of the chemicals specified in this method. A reference file of MSDSs should also be made available to all personnel involved in the chemical analysis. Additional references to laboratory safety are available. (4-6)
5.2 Pure standard materials and stock standards of these compounds should be handled with suitable protection to skin and eyes, and care should be taken not to breathe the vapors or inges

t the materials.
5.3 The toxicity of

the extraction solve

nt, MTBE, has not be

en well defined.

Susceptible individuals may

experience adve

rse affects upo

n skin contact or in

halation of vapor

s. Therefore protective clothing and gloves should be used and MTBE should be used only in a chemical fume hood or glove box. The same precaution applies to pure standard materia

ls.
5.4 Diazomethane is a toxic carcinogen which can explode under certain conditions. The following precautions must be followed.
5.4.1 Use the diazomethane generator behind a safety shield in a w ell ventilated515.4-8 fume hood. Under

no circumstance

s can the gener

ator be heated a

bove 90°C, and all grinding

surfaces such a

s ground glass joints, sleeve bea rings and glass stirrers must be avoided. To minimize safety hazards, the diazomethane generator apparatus used in the esterification procedure (Sect 11.2) produc es micro molar amount

s of diazomethane i

n solution. If th

e procedure is followed caref

ully, no possib

ility for explosion exists.
5.5 Although hydrogen can be safely used as a carrier gas, the potential for fire or explosion does exi

st if the gas system i

s mishandled. If yo

u are unsure of th

e safety guidelines for using hydrogen as a carrier gas, seek advice from your instrument manufacturer regarding its use.
6. APPARATUS AND EQUIPMENT
6.1 SAMPLE CONTAI NERS – Amber glass bottles, approximat ely 40 mL

, fitted with PTFE (polyte

trafluoroethy

lene) lined scre

w caps. 6.2 EXTRACTION V IALS – 60-

mL clear gl

ass vials with PTFE l

ined screw caps

. 6.3 AUTOSAMPLER VIALS – 2.0-mL vials with screw or crimp cap and a PTFE faced seal.
6.4 STANDARD SOLU TION STORAGE

CONTAINERS – 10

to 20-mL amber

glass vials with PTFE line

d screw caps.
6.5 CLEAR VIALS – 7-mL glass, disposable, with PTFE lined screw caps for extract drying and derivatization.
6.6 PASTEUR PIPETTES – Glass, disposable.
6.7 PIPETTES – Class A , 2.0-mL and 4.0-mL glass, o r adjustable volum

e dispensers.
6.8 VOLUME TRIC FLA SKS – Class A, sug geste d siz es inc lude 5 mL, 10 m L, 100 m L.
6.9 MICRO SYRIN

GES – Various sizes.
6.10 BALANCE – Anal ytical, capabl e of weighing t o the neares t 0.0001 g.
6.11 DIAZOMETH

ANE GENERATOR – Se e Figure 4 for

a diagram of an

all glass system custo

m made for these v

alidation studies. M

icro molar gene

rators are also available from commercial sources (Aldrich Cat.#: Z10,889-8 or equivalent).
6.12 GAS CHROMATOGRAPH – Capillary GC (Hewlett Packard Model 6890 or515.4-9 equivalent), if the fast GC option is used the modifications should include a high pressure ( 50 psi) split/splitless injector, fast temperature ramp oven (50 oC/minute) and a low volume (150 μ L ) micro ECD detec tor. Additionally, a

data system capa

ble of fast sampling (20 points/peak) is required

. 6.13 PRIMARY GC COL UMN – RTX-1701, 180

um i.d., fused silic

a capillary

with chemically bonded (14% cya nopropylphenyl-methy

lpolysiloxane), or equivalent bonded, fused silica column.
6.14 CONFIRMATI

ON GC COLUMN – D

B-5, 180 um i.d., f

used silica capill

ary with chemically bonded (5% phenyl-me thylpolysiloxane), or equivalent bonded, fused silica column.
7. REAGENTS AND STANDARDS
7.1 REAGENTS AND SOLVENTS – Reagent grade or better che micals should be used in all analy

ses. Unless other

wise indicated, it

is intended that all

reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are a vailable. Other grades may be used, pro vided it i s first det ermined th at the reagent is of suffi ciently high purity to permit its use without lessening the quality of the determination.
7.1.1 REAGENT WATER – Purif ied water which d

oes not contain an

y measurab

le quantities of any target analy tes or interfering compounds greater than 1/3 the MRL for each compound of interest.
7.1.2 METHYL tert-BUTYL ETHER (MtBE) – Hig h purity, demonstrated to be free from analytes and interference s (HPLC grade or better).
7.1.3 ACETONE – High purity, demonstrated to be free from analy tes and interferences (HPLC grade or better).
7.1.4 CARBITOL (DIETHYLENE G LYCOL MONOETHYL ETH ER) – High purity, demonstrated to be free from analy tes and interferences (HPLC grade or better).
7.1.5 HEXANE:MtBE (90:10, v/v) WASH SOLVENT – High purity, unpreser ved, demonstrated to be free from analytes and interfere nces (HPLC grade or better).
7.1.6 HEXANE – High purity, demonstrated to be free from ana lytes and interferences (HPLC grade or better).515.4-10 7.1.7 SODIUM SULFATE, Na2SO4 – Pesticide grade, g ranular, anhydrous. Interferences have been observed when lowe r quality grades have been used. If interfer ences are obse

rved, it may

be necessary

to heat the sodium su

lfate in a shallow tray at 400 o C for up to 4 hr to remove phthalates and other interfering or

ganic substanc

es. Alternativel

y, it can be e

xtracted with methylene c

hloride in a Soxhlet a

pparatus for 48 h

r. Store in a capp

ed glass bottle rather than a plastic container.
7.1.8 ACIDIFIED SODI UM SULFATE – Acidify by slurrying 100 g of muffled sodium sulfate with

enough ethy

l ether to just cove

r the solid. Add 0.5-

mL concentrated sulfuric acid dropwise while mixing thoroughly. Remove the ether under vacuum. Mix 1 g of the resulting solid with 5-mL of reagent water and measure the pH of the mixture. The pH must be below pH 4. Store in a des icc ato r orat 1 00° C to keep the reag ent dry.
7.1.9 COPPER II SUL

FATE PENTAHYDRA

TE, CUS04 -5H2 0 – ACS reagent grade or better.
7.1.10 4 N SODIUM HYDROXIDE SOLUTI ON – Dissolve 16 g sodium hydroxide (NaOH) pellets (ACS grade or equivalent) in reagent water a nd dilute to 100 mL.
7.1.11 POTASSIUM HYDROXIDE SOLUTI ON (37%, w/v) – Dissolve 37 g of potassium hydroxide (KOH) pellets (ACS grade or equivalent) in reag ent water and di lute t o 100 m L.
7.1.12 SODIUM SULFITE, Na 2 S0 3 – ACS reagent grade, used as a dechlorinating agent in this method.
7.1.13 DIAZAL

D SOLUTIO

N – Prepare a solu

tion containing 5 g

diazald (ACS reagent gra

de) in 50 mL of a

50:50 (v/v) mixture of

MtBE and carbito

l. This solution is stable for one month or longer when stored at 4 °C in an amber bottle with a PTFE lined screw cap.
7.1.14 SULFURIC ACID – Concentrated, ACS rea gent grade.
7.1.15 SILICA GEL

– ACS reagent grade, 35-60 mesh.
7.1.16 HYDROGEN –

99.999% pure or be

tter, GC carrier

gas. 7.1.17 NITROG

EN – 99.999% pure o

r better, ECD make

-up gas. 7.2 STANDARD SOLUTIONS – When a compound purity is assa yed to be 96% or515.4-11 greater, the weight can be used without correction to calculate the conc entration of the stock standard. Solution concentrations listed in this section were used to develop this method and are included as an example. Standards for sample fortification generally should be prepared in the smallest volume that can be a ccurately measured to minimize the addition of organic solvent to aqueous samples. Laboratories should use standard QC pro cedures to deter

mine when Standard Solut ions described in this sec

tion need to be repla

ced.
7.2.1 INTERNAL

STANDARD SOLU

TIONS – 4,4'-Dibromooctaflu orobipheny

l, 99+% is used as an internal standard for the method. This compound has been shown to be an effective internal standard for the method analyte s, but other compounds may

be used if the QC re

quirements in Sect

ion 9 are met.
7.2.1.1 INTERNAL STANDARD STOCK SOLUTI ON (2.0 mg/mL) – Prepare an internal standard a stock solution by accurately weighing app rox ima tel y 0.0 200 g of n eat4,4 '- di bro moo cta flu oro bip hen yl material. Dissolve the neat material in MtBE and dilute to volume in a 10-mL volumetric flask. Transfer the solution to an amber glass vial with a PTFE-lined

screw cap and st

ore at # 0 °C. The resulting concentration of the stock internal standard solution will be approximately 2.0 mg/mL.
7.2.1.2 INTERNAL STANDARD PRIMARY DI LUTION STANDARD (2.5 ug/mL) – Prepare a internal standard fortification solution at approximately 2.5 ug/mL by the addition of 12.5 uL of the stock standard to 10 mL of MtBE. Transfer the primary dilution to an amber glass vial with a PT

FE lined screw c

ap and store at # 0 °C. The solution should be re

placed when ong

oing QC indicates

a problem.
7.2.1.3 MtBE EXTRACTI ON SOLVENT WI

TH INTERNAL

STANDARD (2.5 ug/mL) –

The internal stan

dard 4,4'-dibr

omooctafluorobip

henyl is added to the extrac

tion solvent prior to

analyte extr

action to compensate for a

ny volumetri

c differences

encountered dur

ing sample processing. This solution should be made fresh prior to extraction. The addition of 1 mL

of the primary

dilution standard (

2.5 ug/mL) to 99-mL MtBE results in a final internal standard concentration of 25 ng/mL. This solution is used to extract the samples (Sect. 11.1).
7.2.2 SURROGATE (SUR) ANALYTE STANDARD SOLUTION – 2,4-Dichlorophe

nylacetic acid (99+%) is us

ed as a surroga

te compound in this method to evaluate

the extraction and

derivatization pro

cedures. This compound has been shown to be an effective surrogate for the method analytes, but other compounds may be used if the Q C requirements in Section515.4-12 9 are met.
7.2.2.1 SURROGATE STOCK SOLUTION (1.0 mg/mL) – Prepa re a surrogate stock standard solution of 2,4-dichlorophenylacetic ac id by weighing 0.010

0 g of neat mater

ial. Dissolve the ne

at material in acetone and dilute to volume in a 10-mL volumetric flask. Transfer the solution to an amber glass vial with a PTFE lined screw cap and store at # 0 °C. The resulting concentration of the stock surrogate solution will be 1.0 mg/mL.
7.2.2.2 SURR OGATE PRIMAR Y DILUTIO N STAN DARD/ SUR S AMPLE FORTIFICATION

SOLUTION (100 ug/mL) – Pre pare a primary dilution standard a

t approximately

100 ug/mL by

the addition of 1 mL of the stock standard to 10 mL of acetone. Transfer the primary dilution to an amber glass vial with a PTFE lined screw cap and store at # 0 °C. Addition of 10 ul, of the primary dilution standard to the 40-mL aqueous sample results in a surrogate concentration of 25 ng/mL. The so

lution should be rep

laced when ong

oing QC indicates

a problem.
7.2.3 ANALYTE STANDARD SOLUTION S – Obtain the analytes listed in the table in Section 1.1as neat or solid fr ee acid standar

ds or as commerci

ally prepared ampulized solutions from a reputable standard manufacturer. The use of pre-methy

lated standards i

s not allowed for th

e preparation of

analyte standards. Prepare the Analyte Stock and Primary Dilutions Standards as described below.
7.2.3.1 ANALYTE STOCK STANDARD SOLU

TION – Prepa

re separate stock standard solutions for each analyte of interest at a concentra tion of 1-5 mg/mL in acetone. Method analytes may be obtained as neat materials or ampulized solutions (> 99% purity) from a number of commercial suppliers. These stock standard solutions should be stored at # 0 °C.
7.2.3.1.1 For analytes which are solids in their pure form, prepare

stock standard solutions by accurately we ighing approximately 0.01 to 0.05 grams of pure material in a 10- mL volumetric flask. Dilute to volume with acetone.
7.2.3.1.2 For analytes which are liquid in their pure form at room

temperature, pl

ace about 9.8 mL

of acetone into a

10-mL volumetric flask. Allow the flask to stand, unstoppered, for about 10 minutes to allow solvent film to evaporate from515.4-13 the inner walls of

the volumetric, a

nd weigh to the ne

arest 0.1 mg. Use a 10-uL syringe and immediately add 10.0 uL of standard material t o the flask by keeping the syrin ge needle just above the surface of the acetone. Be sure that the standard material falls dropwise directly into the acetone without contacting the inner wall of the volumetric. Calculate the concentration in milligrams per milliliter from the net gain in we

ight. Dilute to volu

me, stopper, then m

ix by inverting

the flask severa

l times.
7.2.3.2 PRIMARY DILUTI ON STANDARD (PDS) – Prepare the primary dilution standard solution by combining and diluting stock standard solutions with acet

one. This primary

dilution standard s

olution should be stored at # 0 °C. As a guideline to the analyst

, the analyt

e concentrations used in the primary dilution standard solution during method development are given below.

Analyte Concentration (ug/mL) Acifluorfen 5.0 Bentazon 10 Chloramben 5.0 2,4-D 10 Dalapon 10 2,4-DB 10 Dacthal acid metabolites 5.0 Dicamba 5.0 3,5-Dichloroben

zoic acid 5.0 Dichlorprop 10 Dinoseb 10 Pentachlorophenol 1.0 Picloram 5.0 2,4,5-T 2.5 2,4,5-TP (Silvex) 2.5 Quinclorac 5.0515.4-14 This primary dilution standard is used to fortify reag ent water for calibration standards. The lowest calibration standard concentration must be at or below the MRL of each analyte. The concentrations of the other standards should define a range containing the expected sample concentrations or the working range of the detector.
7.2.4 CALIBRA

TION STANDAR

DS (CAL) – A fiv

e-point calibra

tion curve is to be prepared by fortify

ing reagent water with the primary dilution standard. A designated amount of each calibration stand

ard in acetone is

spiked into separate 40-mL aliquots of reagent water to produce a calibration curve ranging from

below or at the MRL

to approximately

10-20 times the lowe

st calibration level. These aqueous calibration standards should be treated like samples and therefore require the addition of all preservation and other reagents. They are extracted by the procedure described in Section 11. The calibration stand

ard solutions in ac

etone should be sto

red at # 0 °C.
8. SAMPLE COLLECTION , PRESERVATION, AND ST ORAGE
8.1 SAMPLE BOTTLE PREPARATION
8.1.1 Grab samples must be collected in accordance with conventional sampling practices (7)using amber glass containers with PTFE lined screw caps and capacities of at least 40 mL.
8.1.2 Add sodium sulfite crystals (approximately 2 mg/40 mL of sample) to the sample bottle prior to collecting the sample. This reagent eliminates residual chlorine in the sample.
8.2. SAMPLE COLLECTION
8.2.1 Fill sample bottles but take care no

t to flush out the sodiu

m sulfite. Becau

se the target analytes of this method are not volatile, it is not necessary to ensure that the sample bottles are completely headspace free.
8.2.2 When sampling from a water tap, remove the aerator so that no air bubbles will be trapped in t

he sample. Open th

e tap and allow the

system to flus

h until the water temperature has stabilized (usually about 3-5 minutes). Collect samples from the f

lowing syst

em. 8.2.3 When sampling fro m an open body

of water, fill a 1quart wide-mouth b ottle or 1 liter beaker

with sample from a

representative

area, and car

efully fill sample vials from the container.515.4-15 8.2.4 After collectin

g the sample, sea

l the bottle and ag

itate by han

d for 15 seconds.
8.3 SAMPLE SHIPMENT AND STORAGE – All samples should be iced during shipment and must not exceed 10 o C during the first 48 hours after collection. Samples should be confirmed to be at or below 10 o C when they are received at the laboratory. Samples stored in the lab must be held at or below 6 o C and protected from light until extraction. Samples should not be frozen.
8.4 SAMPLE AND EXTRACT HOLDING TI MES – Because of the several pH adjustments made to

the samples in the c

ourse of this metho

d, the addition of or

ganic or inorganic bio

cides, including

hydrochlor

ic acid, have be

en omitted. The an

alyst should be aware of the potential for the biological degradation of the analy tes. Accordingly, samples should be extracted as soon as possible. Samples must be extracted within 14

days. Extrac

ts must be stored at # 0 o C or less and protected from light in glass vials with PTFE lined caps. Holding time studies indicate that the analytes a re stable for up t

o 21 days in th

e extracts.
9. QUALITY CONTROL
9.1 Quality con

trol (QC) require

ments include the I

nitial Demonstrati

on of Capability (Sect. 17, Table 13), the determination of the Detection Limit, and subsequent analysis in each analysis batch of a Laboratory Reagent B

lank (LRB), Continuing Calibration Check Standards (CCC), a Laboratory Fortified Sample Ma trix (LFM), and either a L

aboratory Fortified Sample

Matrix Duplicate (L

FMD) or a Field Duplicate Sample. This section details the specific requirements for each QC parameter. The

QC criteria discu

ssed in the followin

g sections are s

ummarized in Section 17, Tables

13 and 14. These c

riteria are con

sidered the minimum

acceptable QC criteria, and

laboratories ar

e encouraged

to institute addition

al QC practices to meet their specif

ic needs. 9.1.1 Process all quality control samples through all steps of Section 11, including hydrolysis and methy

lation. Sample preservatives as described in Section 8.1 must be added prior

to extracting and

analyzing t

he quality c

ontrol samples.
9.2 INITIAL

DEMONSTRATION OF CAPABIL ITY (IDC) – Requirements for the Initial Demonstration of Capability are described in the following sections and summarized in Section 17, Table 13

. 9.2.1 INITIAL

DEMONSTRATION OF LOW SYSTEM BACKGROUND – Before any samples are analy zed, it must be demonstrated that a laboratory reagent blank

(LRB) is rea

sonably fre

e of contaminatio

n and that the crit

eria in Section 9.4 are met. Process all quality control samples through all all steps of the method (Sect. 9.1.1).515.4-16 9.2.2 INITIAL

DEMONSTRATION OF PRECISION – Prepar e, extract, and analyze 4-7 replicate LFBs fortified at 5 ug/L, or near the mid-range of the initial calibratio

n curve. Process

all quality c

ontrol samples thro

ugh all all steps of the method (Sect. 9.1.1). The relative standard deviation (RSD) of the results of the replicate analyses must be less than 20%.
9.2.3 INITIAL

DEMONSTRATION OF ACCURACY – Using the same set of replicate data generated for Section 9.2.2, calculate averag e recovery. The average recovery of the r

eplicate values must be within ± 20% of the true value.
9.2.4 DETECTION L

IMIT – Pre

pare, extract an

d analyze at

least seven repl

icate LFBs at a concentration estimated to be near the Detection L imit, over a period of at least three days (both extraction and analy sis should be conducted over at least thre

e days) usin

g the procedur

e described in Se

ction 11. Process all quality control samples through all all steps of the method (Sect. 9.1.1). The fortification level may be estimated by selecting a concentration with a signal of 2 to 5 times the noise level but must be at or below the laboratory’s MRL (Sect. 9.3). The appropriate concentration will be dependent upon the sensitivity of the GC/ECD system being used. Sample preserva tives as described in Section 8.1 must be added to these samples. Calculate the Detection Limit using the equation
Detection Lim

it = St(n - 1, 1 - alpha = 0.99) where t(n - 1, 1 - alpha = 0.99)

= Students t value for the 99% confidence level with n1 degrees of f

reedom, n = number of replicates, and S = standard devia

tion of replicate

analyses. NOTE: Calculated Detection Limits need only be less than 1/3 of the laboratory’s MRL to be considered acc eptable. Do not subtract blank values when performing

Detection Lim

it calculations. T

he Detection L

imit is a sta tis tic al d ete rmi nat ion of p reci sio n on ly. (1)If the Detection Limit replicates are fortified at a low enough concentration, it is likely that they will not meet precision and ac

curacy c riteria, and may

result in a calcu

lated Detection L

imit that is higher than the fortified concentration
9.2.5 METHOD MODIFICATI ONS – The analyst is permitted to modify GC columns, GC conditions, internal standards or surrogate standards, but each time such method modifications are made, the analyst must repeat the procedures of the IDC (Sect. 9.2).515.4-17

9.3 Minimum Reporting Level (MRL) – The MRL is the threshold conce ntration of an analyte that a laboratory c an expect to accurately quantitate in an unknown sample. The MRL should not be established at an analyte concentra tion that is less than either three times the De

tection Limit or

a concentration

which would y

ield a response le

ss than a signal-to

-noise (S/N) rati

o of five. Depend

ing upon the study

’s data quality objectives it may be set at a higher concentration. Although the lowest calibration standard must be at or below the MRL, the MRL must never be established at a concentration lower than the lowest calibration standard

. 9.4 LABORATORY REAGENT BLANK (L RB) – An LRB is required with each extraction batch (Sect. 3.1) of samples to determine the background system contamination. If the LRB produces a peak within the rete ntion time window of any analyte that would prevent the determination of that analy te, determine the source of contamination and eliminate the interference before processing samples. Backg round contamination must be reduced to an acceptable level before proceeding. Background from method analytes or contaminants that interfere with the measurement of method analytes mu

st be below 1/3 of th

e MRL. If t

he target ana

lytes are d

etected in the L

RB at concentrations equal to or greater than this level, then all data for the problem analyte(s) must be considered invalid for all samples in the extraction batch.
9.5 CONTINUI

NG CALIB

RATION CHECK (

CCC) – A standard pr

epared in the sam

e extraction batch as the samples of interest that contains all compounds of interest and is extracted in the same manner as the procedural standards used to prepare the initial calibration curve. Calibration checks, prepared with the samples being analy zed, are required at the beginning of each day that samples are analyzed, after every ten samples, and at the end of any group of sample analy ses. See Section 10.3 for concentration requirements, frequency require ments, and acceptance criteria.
9.6 LABORATORY FORTIFI ED BLANK (LFB) – Since this method utilizes procedural calibration standards, which are fortified reagent waters, there is no differ ence between the LFB and the continuing calibration check standa rd. Consequently, the analysis of

an LFB is not r

equired ; howeve

r the acrony

m LFB is used f

or clarity i

n the IDC.
9.7 INTERNAL STANDARDS (IS) – The ana lyst must monitor the peak area of each internal standard in all injections during each analysis day . The IS response (as indicated by peak area) for any chromatographic run must not deviate by more than ± 50% from the average area measured during the initial calibration for that IS. A poor injection could cause the IS area to exceed these criteria. I nject a second aliquot of the suspect extract to determine whether the failure is due to poor injection or instrument respon

se drift.515.4-18 9.7.1 If the reinjected aliquot produces an acceptable internal standar d response, report results fo

r that aliquot.
9.7.2 If the internal standard area for the reinjected extract devia tes greater than 50% from the initial calibration average, the analyst should check the conti nuing calib ratio n chec k stan dards that r an before an d afte r the s ample . If the continuing calibration check fails the criteria of Section 10.3, recalibration is in order per Section 10. If the calibration standard is acceptable, extraction of the sample should be repeated provided the sample is still within holding time. Otherwise, report results obtained from the reinjected extract, but annotate as suspe

ct.
9.8 SURROGATE RECOVERY – The surrogate standard is fortified into the aqueous portion of all sampl

es, LRBs, and

LFMs and L

FMDs prior to extra

ction. It is als

o added to the calib

ration curve and

calibration che

ck standards. The

surrogate is a means of assessin

g method perfor

mance from extrac

tion to final chroma

tographic measurement.
9.8.1 When surrogate recovery from a sample, blank, or CCC is less than 70% or greater than 130%, check (1) calculations to locate possible errors, (2) standard solutions for degradation, (3) contamination, and (4) instrument performa nce. If those steps do not re

veal the c ause of th e problem

, reanaly ze the extract.
9.8.2 If the extrac

t reanalys is meets the surrog

ate recovery

criterion, repo

rt only data for the reanaly

zed extract.
9.8.3 If the extrac

t reanalys is fails the 70-130

% recovery

criterion, the a

nalyst should check the calibration by injecting the last calibration standard that passed. If the calibration standard fails the criteria of Section 9.8.1, recalibration is

in order per Sec

tion 10.2. If th

e calibration sta

ndard is acceptable, e

xtraction of the sam

ple should be repe

ated provided the

sample is still within the holding time. If the sample re-extract also fails the recovery criterion, repo

rt all data for tha

t sample as suspec

t/surrogate re

covery to inf orm the dat a us er t hat the res ult s ar e su spe ct d ue t o su rro gate reco very. 9.9 LABORATORY FORTIFI ED SAMPLE MATRIX AND DUPLI CATE (LFM AND LFMD) – Analyses of L

FMs (Sect. 3.7) are required in each extraction batch and are used to determine that the sample matrix does not adversely affect method accura cy. If the occurrence of target analy tes in the samples is infrequent, or if historical trends are unavailable, a second LFM or LMF D must be prepared, extracted, and analyzed from a duplicate field sample used to prepare the LFM to assess method precision. Extraction batche

s that contain L

FMDs will not requi

re the analy

sis of a Field515.4-19 Duplicate (Sect. 9.10). If a variety of different sample matrices are analyzed regularly , for example, drin

king water fro

m groundwater a

nd surface wate

r sources, method performance should be established for each. Over time, LFM data should be documented for all routine sample sources for the laboratory.
9.9.1 Within each extraction batch, a minimum of one field sample is fortified as an LFM for every 20 sam ples extr acted. The LFM i s prepared by sp iking a sample with an app

ropriate amount o

f Analyte PDS (Sect. 7.2.3.2). Select a spiking concentration that is at least twice the matrix background concentration, if known. Use historical data and rotate through the designated concentrations when selecting a fortifying c oncentration.
9.9.2 Calculate the percent recovery (R) for ea ch analyte using the equation

where A = measured concentration in the fortified sample, B = measured concentration in the unfortified sample, and C = fortification concentration.
9.9.3 Analyte recoveries may exhibit matrix bias. For samples fortified at or above their native concentration, recoveries should range between 70 and 130%, except for low-level fortification near or at the MRL where 50 to 150% recoveries are acceptable. If the ac curacy of any a

nalyte falls outside the designated ra

nge, and the lab

oratory pe

rformance for

that analyt

e is shown to be in control in the LFB, the recovery is judged to be matrix biased. The result for that an

alyte in the

unfortified sampl

e is labeled suspe

ct/matrix to inform the data us

er that the result

s are suspect due

to matrix effects.
9.9.4 If an LFMD is analy zed instead of a Field Duplicate (Sect. 9.10), calculate the relative percent difference (RPD) for duplicate LF Ms (LFM and LFMD) using the equation

RPDs for duplicate LFMs should fall in the range of ± 30% for samples fortified at or above their native concentration. Greater variability may be observed when L

FMs are spiked ne

ar the MRL. At t

he MRL, RPDs shou

ld fall in the range of ± 50% for samples fortified at or above their native515.4-20 concentration. If the accuracy of any analyte falls outside the desig nated range, and the

laboratory

performance f

or that analy

te is shown to be in control in the LFB, the recovery is judged to be matrix biased. The result for that analyte in the unfortified sample is labeled suspect/matrix to inform the data user that the

results are suspe

ct due to matrix eff

ects.
9.10 FIELD DUPLI

CATES (FD1 AND FD2) – Within each extraction batch, a minimum of one Field Duplicate (FD) or LFMD (Sect. 9.9) must be analy zed. FDs check the precision associated with sample collection, preservation, storage, and laboratory procedures. I

f target analy

tes are not routin

ely observe

d in field samples, a

LFMD (Sect. 9.10) should be analyzed to substitute for this requirement. Extraction batches that contain LFMDs will not require the analysis of a F ield Duplicate.
9.10.1 Calculate the re

lative percent d

ifference (RPD

) for duplicate me

asurements (FD1 and FD2) using the equation

9.10.2 RPDs for duplicates should be in the range of ±30% . Greater variability may be obs erved when a nalyte conce ntrat ions a re nea r the M RL. At t he MRL, RPDs should fall in the range of ±50%. If the a ccuracy of any ana

lyte falls outside the desig

nated range, a

nd the laboratory

performance f

or that analy

te is shown to be in cont

rol in the LFB, the recovery is judged to be mat

rix biased. The result for that analyte in the unfortified sample is labeled suspect/matrix to inf

orm the data user

that the results ar

e suspect due to ma

trix effects.
9.11 QUALITY CONTROL SAMPL ES (QCS) – A QCS sample should be analyzed each time that new Primary Dilution Standards (Sect. 7.2.3.2) are prepared. The source of the QCS sample should ideally be a second vendor. If a se cond vendor is notavailable then a different lot of the standard should be used. Although the use of premethylated standards is prohibited for preparing analyte standard solutions, premethylated standards may be used to pre pare the QCS. The QCS may be injected as a calibration standard or fortified into reagent water and analy zed as a LFB. If the QCS is analyze

d as a continuing

calibration, the

n the acceptanc

e criteria are

the same as for the CCC. If the QCS is analyzed as a L FB, then the acceptance criteria are the same as for an L

FB. If mea

sured analy

te concentratio

ns are not of acc

eptable accuracy, check the entire analy tical procedure to locate and correct the problem source.515.4-21

10. CALIBRATION AND STAN DARDIZATION
10.1 After initial cal

ibration is succe

ssful, a Continuing

Calibration Check

(CCC) is required at the b

eginning and e

nd of each analy

sis batch, and aft

er every t enth sample (Sect. 10.3). Be

cause this is a pro

cedural standar

d method, the analy

st will need to make a decision to include an appropriate number of CCCs or an entire initial calibration curve with each extraction batch. Initial calibration should be repeated each time a major instrument modification or maintenance is performed.
10.2 INITIAL

CALIBRATION
10.2.1 Establish GC operating parameters equivalent to the suggested specifications in Section 17, Table 1. The GC system must be calibrated using the internal standard (IS) technique. Othe r columns or condit

ions may be us

ed if equivalent or better performance can be demonstrated.
10.2.2 Prepare a set of at least 5 calibration standards as described in Section 7.2.4. The lowest concentration of calibration standard must be at or below the MRL, which will depend on system sensitivity.
10.2.3 CALIBRATION – Use the GC data system software to generate a linear regression or quadratic calibration curve using the internal standard. The analyst may

choose whether o

r not to force zer

o to obtain a curve

that best fits the data. Examples o

f common GC sy

stem calibration c

urve options are: 1)Ax/Aisvs Q x/Q isand 2) RRF vs A x/Ais . where: Ax= integrated peak area of the analyte , Ais= integrated peak area of the internal standard, Q x= quantity of a

nalyte inje

cted in ng or con

centration units, and Q is= quantity of internal standard injected in ng or concentration

units.
10.2.4 As a n alternati ve, concent rations ma y be calculated t hrough the u se of average relative response factor (RRF). Calculate the RRFs using the equation

Average RRF calibrations may only be used if the RRF values over the515.4-22 calibration ran

ge are relati

vely consta

nt (<30% RSD). Ave

rage RRF is determined by calculating the mean RRF of a minimum of five calibration concentrations.
10.2.5 Acceptance criteria for the calibration of each analy te is determined by calculating the concentration of each analy te and surrogate in each of the analyses used to generate the calibration curve or average RRF. Each calibration point, except the lowest point, for each analyte must calculate to be 70-130% of its true value. The lowest point must calculate to be 50-150% of its true value. If this criteria cannot be met, reanaly ze the calibration standards, restrict the range of calibration, or select an alternate method of calibration.
10.3 CONTINUI

NG CALIB

RATION CHECK (

CCC) – An appropria

te number of CCCs must be prepared with each extraction batch. The CCC verifies the initial calibration at the beginning and end of each group of analy ses, and after every 10 thsample during analyses. In this context, a “sample” is considere d to be a field sample. LRBs, LFMs, LFMDs and CCCs are not counted as samples. The beg inning CCC for each analysis ba

tch must be at or be

low the MRL in or

der to verify

instrument sensitiv

ity prior to any

analyses. I

f standards have

been prepared

such that all low CAL

points are not in the same CAL solution, it may be necessary to analyze two CAL solutions to meet this requirement. Subsequent CCCs should alternate between a medium and high concentration.
10.3.1 Inject an aliquot of the appropriate concentration calibration check standa rd solution prepare

d with the extractio

n batch and analy

ze with the same conditions used during the initial calibration.
10.3.2 Calculate the concentration of each analyte and surr ogate in the check standard. The calculated amount for each analyte f or medium and high level CCCs must be ± 30% of the true value. The c

alculated amount

for the lowest calib ratio n leve l for e ach an alyte m ust be withi n ± 50% of the true v alue. If these conditions do not exist, then all data for the problem analyte must be considered invalid, and remedial action should be taken which may require recalibration.

Any field sa

mple extracts that h

ave been analy

zed since the last acceptable ca

libration verific

ation should be rea

nalyzed aft

er adequate calibration has been restored, with the following exception. If the continuing calibration fails because the calculated concentration is greater than 130% (150% for the low

-level CCC) for a p

articular targ

et compound, and f

ield sample extracts show no detection for that target compound, non-detects may be reported with

out re-analy

sis.515.4-23

11. PROCEDURE
11.1 SAMP LE EXTR ACTION AND HY DROLYS IS
11.1.1 Remove the samples from storage (Sect. 8.3) and all ow them to equilibra

te to room temperature.
11.1.2 Place 40 mL of the water sample into a precleaned 60-mL , glass vial with a PTFE lined screw cap using a graduated cy linder.
11.1.3 Add 10 uL of sur

rogate standa

rd (100 ug/mL

, 2,4-dichlorophe

nylacetic acid in acetone per Section 7.2.2) to the aqueous sample.
11.1.4 Add 1 mL, of the

4 N NaOH solution pr

epared in Section

7.1.10 to each g

lass vial. Check the pH

of the sample with p

H paper or a pH me

ter. If the sa

mple does not have a pH greater than or equal to 12, adjust the pH by a dding more 4 N NaOH solution. Let the sample sit at room temperature for 1 hour, sha kin g the con ten ts p eri odi cal ly.
NOTE: Since many o

f the herbicides

contained in this me

thod are applied a

s a variety of esters and salts, it is vital to hydroly ze them to the parent acid prior to extraction. This s

tep must be include

d in the analy

sis of all extracte

d field samples, LRBs, LFMs and calibration standards. Failure to pe rform this step may result in

data that are bia

sed low for some ta

rgets in field sa

mples. (8)
11.1.5 Following hydrolysis, add 5 mL of (90:10, v:v) hexane:MtBE (Section 7.1.5) and shake vigorously for three minutes. Allow the phases to separate f or approximately 5 minutes then remove and discard the top hexane/MtBE lay er. This wash aids in sa

mple cleanup and

removes any

Dacthal from the

sample which would interfere with the quantitation of the Dacthal metabolites.
11.1.6 Adjust the pH to approximately 1 by adding concentra ted sulfuric acid. Cap, shake and then check the pH with a pH meter or narrow range pH pape r. Add additional sulfuric acid as needed to properly adjust the pH.
11.1.7 Quickly add approximately 2 g of coppe r II sulfate pentahy

drate and shake until dissolved. This

colors the aqueo

us phase blue and a

llows the analy

st to better distinguis

h between the aqu

eous phase and the

organic phase

in this micro extraction.
11.1.8 Quickly add approximately 16 g of muffled sodium sulfate ( Sect. 7.1.7) and shake until almost all is dissolved. Sodium sulfate is added to increase the ionic stre ngth of th e aqueous phase and

thus furth

er drive t he chloro phenoxy515.4-24 acids into the org

anic phase. The a

ddition of salt also d

ecreases the so

lubility of MtBE in the aqueous phase and allows greater volumetric recovery . The addition of this salt and the copper II sulfate pentahy drate should be done quickly so that the heat generated from the addition of the acid (Sec tion 11.1.6) will help di

ssolve the salts.
11.1.9 Add exactly 4.0-mL MtBE and shake vigorously for three minutes. 11.1.10 Allow the ph

ases to separate

for approximately

5 minutes.
11.2 SAMPLE METHYLATION WI TH DIAZOMETHANE
11.2.1 GENERATION OF DIAZOMETH ANE
11.2.1.1 Assemble the diazomethane generator (Figure 4) in a hood. The

collection vessel is a 10- or 15-mL, glass vial equipped with a PTFE lined screw

cap that is maintai

ned at 0 - 5 °C.
11.2.1.2 Add a sufficient amount of MtBE (approximately 7 mL) to tube 1

to cover the first impinger. Add 10 mL of MtBE to the collection vial. Set the nitrog

en flow at 5-10 mL

/min. Add 4-mL D

iazald solution (Sect. 7.1. 13) and 3 mL of 37% KOH solution (Se

ct. 7.1.11) to the second impinger. Connect the tubing as shown and allow the nitrogen flow to purge the diazomethane from the reaction vessel into the collection vial for 30 minutes. Cap the vial when collection is complete and maintain at 0-5 °C. When stored at 0-5 °C, this diazomethane solution may be used over a period of 72 hours.
11.2.1.3 Several commercial sources of glassware are available for

diazomethane generation. These include a mini Diazald apparatus from Aldrich (Cat. #:Z10,889-8).
11.2.2 Using a Pasteur pipette, transfer the sample extract (upper MtBE lay er) to a 7- mL, screw cap vi al. Add 0.6 g acidified sodium sulfate (Sect. 7.1.8) and shake. This step is i

ncluded to dry

the MtBE extract.
11.2.3 Using a Pasteur p

ipette, transfer

the extract to a sec

ond, 7-mL gla

ss vial.
11.2.4 Add 250 uL of the diazomethane solution prepared in Section 11.2.1 to each vial. The contents of the vial should remain slightly yellow in color indica ting an excess of diazome

thane. Additional

diazomethane may

be added if necessary . Let the este

rification reac

tion proceed for

30 minutes.515.4-25 11.2.5 Remove any unreacted diazomethane by adding 0.1 g of silica gel. Effervescenc

e (evolution of nit

rogen) is an ind

ication that excess diazomethane was present. Allow the extracts to sit for 0.5 hour.
11.2.6 Transfer the extract to an autosampler vial. A duplicate vial may be filled using the excess e

xtract.
11.2.7 Analyze the sample extracts as soon as possible. The sample extract may be stored up to 21 days if kept at 0 °C or less. Keep the extracts away from light in amber glass vi

als with PTFE lined c

aps. 11.3 GAS CHROMATOGRAPHY
11.3.1 If the fast GC option is used, several important changes from “conventional GC” should be made to aid in the rapid analysis of the analytes. The instrument should have a fast temperature ramp (50 ° C/minute) oven and a high pressure ( 50 psi) split/splitless injector. When u sing columns with diameters less than 180 um the instrument should be equipped with a low volume (150 μ L ) micro ECD. Addit ionally, the column

diameter and film thickness should be

decreased and

the carrier ga

s should be change

d to hydrogen.
11.3.2 Use of Hydrogen Safely – Although hydrogen can be used safely as a carrier gas, the potential

for fire or expl

osion does exist if th

e gas system is mishandled. If you

are unsure of the

safety guideline

s for using hydroge

n as a carrier gas, seek advice from your instrument manufacturer regarding its use.
11.3.3 Column Selection and Installation – During method development the RTX1701 columns provid

ed baseline reso

lution for the 2,4-

DB /Chloramben pair (peaks 11 and 12 in Figure 1). Columns from other manufacturers were not as effective in se

parating these a

nalytes. Strict att

ention must be paid t

o established column installation guidelines with regard to the proper cutting and placement of the capillary columns within the instrument. Additionally, a loss of response ov

er time was note

d for Acifluorifen and Dinoseb. Trimming approximately 1 meter from the head of the column restored the response for these analy

tes. If condi

tions in the labora

tory necessitate frequent c olumn trimming, a guard column is recommended.
11.4 ANALYSIS OF EXTRACTS
11.4.1 Establish operati

ng conditions as d

escribed in Secti

on 17, Table 1 (Ta

ble 2 if performing confirmation). Confirm that retention times, compound separation and resolution are similar to those summarized in Table 1 and Figure1.515.4-26 11.4.2 Establish an appro priate retention

time window for ea

ch target and s

urrogate to identify them in the QC and field samples. This should be based on measurements of

actual retention

time variation for

each compound in standard solutions analyzed on the GC over the course of time. Plus or minus three times the standard deviation of the retention time for each compound while establishing the initial calibration and completing the IDC can be used to calculate a su

ggested windo

w size; however, th

e experience of t

he analyst should weigh heavily on the determination of the appropriate retention window size.
11.4.3 Check system calibration by analy zing a CCC (Sect. 10.3) and calibrate the system by either the analy sis of a calibration curve (Sect. 10. 2) or by confirming the initial calibration is still valid by analyzing a continuing calibration check as described in Section 10.3. Begin analy zing field and QC samples at their a

ppropriate fre

quency by

injecting the sa

me size aliquots under the same conditions used to analyze the initial calibration.
11.4.4 An ana lyst mu st not extr apola te beyo nd the estab lish ed cal ibrat ion ra nge. If an analyte result exceeds the range of the initial calibration cur ve, the extract may be diluted with MtBE containing the internal standard (Sect. 7.2.1.3), and the diluted extract injected. Acceptable surrogate performance (Sect. 9.8) should be determined from the undiluted sample extract. Incorporate the dilution factor int

o final concentr

ation calculation

s. The dilution will a

lso affect analyte MRLs.

12. DATA ANALYSIS AND C ALCULATION
12.1 Identify the method analy tes in the sample chromatogram by comparing the rete ntion time of the suspect peak to retention time of an analyte peak in a calibration standar d. Surrogate rete

ntion times should be

confirmed to be w

ithin acceptanc

e limits (Sect. 11.4.2) even if no target compounds are detected.
12.2 Calculate the analyte concentrations using the initial calibration curve g enerated as described in Sec

tion 10.2. Quantita

te only those

values that fall be

tween the MRL and the highest calibration standard. Samples with target analyte r esponses that exceed the highest standard require dilution and reanalysis (Sect. 11.4.4).
12.3 Analyte identifications should be confirmed using the confirmation column specified in Table 2 or anoth

er column that is dissimilar to the prima ry column or

by GC/MS if the concentrati

ons are sufficie

nt.
12.4 Adjust the calculated concentrations of the detected analytes to re flect the initial515.4-27 sample volume and any dilutions performed.
12.5 Analyte co

ncentrations ar

e reported in ug

/L as the total f

ree acid. Calcu

lations should use all available digits of precision.
13. METHOD PERFORMANCE
13.1 PRECISION, ACCURACY, AND Detection Limits – Tables for these data a re presented in Section 17. Single laboratory precision and accura cy data are presented in Tables 5 -10. Detection Limits are presented in Table 4 and were calcula ted using the formula presented in Section 9.2.4.
14. POLLUTION PREVEN TION
14.1 This m ethod util izes liqu id:l iqui d micr oext racti on to e xtra ct ana lytes f rom wa ter. It requires the use of very small volumes of organic solvent and ver y small quantities of pure analytes, thereby minimizing the potential hazards to both the ana lyst and the environment as co

mpared to the use o

f large volumes

of organic solv

ents in conventional liquid-liquid extractions.
14.2 For information about pollution prevention that may be applicable to laboratory operations, cons

ult “Less is Be

tter: Labora

tory Chemica

l Management fo

r Waste Reduction” available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16th Street N.W., Washington, D.C., 20036.
15. WASTE MANAGEMENT
15.1 The analyt

ical procedure

s described in this

method genera

te relatively

small amounts of waste since only small amounts of reagents and solvents are used. The matrices of concern are finished drinking water or source water. Howeve r, the Agency requires that laboratory

waste managem

ent practices be

conducted consis

tent with all applicable rules and regulations, and that laboratories protect the air, water, and land by minimizing and controlling all releases from fume hoods and bench operations. Also, compliance

is required with a

ny sewag e discharge pe

rmits and regula

tions, particularly the hazardous waste identification rules and land disposal restrictions. For further information on waste management, consult “The Waste Management Manual for Laboratory Personnel” a lso available from the American Chemical Society at the address in Section 14.2.515.4-28

16. REFERENCES
1. Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., and Budde, W.L., “Trace Analyses for Wastewaters,” Environ. Sci. Tec hnol. , 15(1981) 1426-1435.
2. Giam, C.S., Chan, H.S., and Nef, G.S., "Sensitive Method for Determination of Phthalate Ester Plas ticizers in Open-Ocean Bi ota Samples," Analytical Chemistry,47, 2225 (1975).
3. Giam, C.S., and Chan , H.S., "Control of

Blanks in the Ana

lysis of Phtha

lates in Air and Ocean Biota Samples," U.S. National Bureau of Standards, Special Publication 442, 701-708, (1976).
4. "OSHA Safety and Health Standards, General I ndustry," (29CRF1910). Occupational Safety and Health Administration, OSHA 2206, (Revised, Jan.1976).
5. “Carcinogens-Working with Carcinogens,” Publication No. 77-206, Department of Health, Educatio

n, and Welfare, Pu

blic Health Servic

e, Center for Dis

ease Control, National Institute of Occupational Safety and Hea lth, Atlanta, Georgia, August 1977.
6. “Safety In Academic Chemistry Laboratories,” 3rd Edition, American Chemical Society Publication, Committee on Chemical Safety, Washington, D.C., (1979).
7. ASTM Annual Book of Standards, Part II, Volume 11.01, D3370-82, "Standard Practice for Sam

pling Water," A

merican Society

for Testing and

Materials, Philadelphia, PA, 1986.
8. Bassett, M.V.; Pep ich, B.V. and Mun

ch, D.M., “The Rol

e Playedby

Basic Hyd

rolysis in the Validity of Acid herbicide Data - Recommendations for Future Prepa ration of Herbicide Performance Evaluation Standards.” Environ

. Sci

. Technol ., Vol.34, 1117, (2000).515.4-29

17. TABLES, DIAGRAMS, F LOWCHARTS, AND VALID ATION DATA
TABLE 1: CHROMATOGRAPHIC CONDITIONS AND AVERAGE RETENTION TIME DATA FOR THE PRIMARY COLUMN (RTX-1701, 40m x 180 um i.d.)

Peak Number (Figure 1) Compound Average T r (min) a % RSD
1 Dalapon 7.06 0.017 2 3,5 Dichlorobenzoi c acid 11.32 0.002 3 2,4-Dichlorophe nylacetic acid (SUR) 11.80 0.002 4 Dicamba 11.91 0.002 5 Dichlorprop 12.21 0.002 6 4,4'-Dibromooc tafluorobipheny

l (IS) 12.25 0.002 7 2,4-D 12.37 0.002 8 Pentachlorophenol 12.49 0.002 9 Silvex 12.70 0.002 10 2,4,5-T 12.90 0.002 11 2,4-DB 13.10 0.003 12 Chloramben 13.15 0.003 13 Dinoseb 13.44 0.003 14 Bentazon 13.60 0.003 15 Dacthal 13.68 0.002 16 Quinclorac 13.85 0.004 17 Picloram 14.02 0.003 18 Acifluorfen 15.20 0.004

a The average reten tion time represents the average of 7 runs. Primary Column: DB-1701, 40 m x 0.180 mm i.d., 0.20 μ m film thickness, injector te mp. 200 oC, liner 2 mm straight s iltek ® deactivat

ed, injection volume 1 μ L of 20 0 ng/m L (high est level com ponen t) standard , splitless injection hold to 1 min then purge @ 50 mL/min, det ector te mp 360 oC, detecto r make up gas n itrogen at 2 0 mL /minute. Temperature progr

am: 45 oC initi

al, progr am at 5 oC/minute to 80 oC, Then 50 oC/minute to 220 oC, Then 20

oC/minute to 280 oC and Hold for 3 min, Data col lection vi

a HP GC Chemstation at a rate of 20Hz.
Carri er gas: Hydr

ogen ( UHP)

Detector ma

keup gas: Ni

trogen (UHP)515.4-30

TABLE 2: CHROMATOGRAPHIC CONDITIONS AND AVERAGE RETENTION TIME DATA FOR THE CONFIRMATION COLUMN (DB-5, 40 m x 180 um i.d.)

Peak Number (Figure 1) Compound Average T r (min) a % RSD
1 Dalapon 5.04 0.057 2 3,5-Dichloroben zoic acid 10.33 0.007 3 2,4-Dichlorophe nylacetic acid (SUR) 11.31 0.004 4 Dicamba 11.46 0.006 5 Dichlorprop 12.19 0.006 6 4,4'-Dibromooc tafluorobipheny

l (IS) 12.71 0.004 7 2,4-D 12.34 0.005 8 Pentachlorophenol 13.16 0.006 9 Silvex 13.29 0.004 10 2,4,5-T 13.48 0.005 11 2,4-DB 13.94 0.005 12 Chloramben 13.34 0.004 13 Dinoseb 14.01 0.004 14 Bentazon 14.28 0.006 15 Dacthal 15.00 0.004 16 Quinclorac 14.88 0.004 17 Picloram 14.59 0.004 18 Acifluorfen 16.38 0.003

a The average reten tion time represents the average of 7 runs.
Confirmation Column: DB-5, 40 m x 0.180 mm i.d., 0.20 μ m film thickness, injector te mp. 200 oC, liner 2 mm straight s iltek ® deactivat

ed, injection volume 1 μ L of 10 0 ng/m L (high est level com ponen t) standard , splitless injection hold to 1 min then purge @ 50 mL/min, det ector te mp 360 oC, detecto r make up gas n itrogen at 2 0 mL /minute. Temperature progr

am: 45 oC initi

al, progr am at 4 oC/minute to 80 oC then program at 30 oC/minute to 280 and Hold for 2 min, Data coll ection via HP GC Chemstation at a rate of 20Hz.
Carri er gas: Hydr

ogen ( UHP)

Detector ma

keup gas: Ni

trogen (UHP)515.4-31

TABLE 3: CHROMATOGRAPHIC CONDITIONS AND AVERAGE RETENTION TIME DATA FOR A CONVENTIONAL PRIMARY COLUMN (DB-5, 30 m x 250 um i.d.)

Peak Number (Figure 3) Compound T r (min) 1 Dalapon 14.28 2 3,5-Dichloroben zoic acid 20.35 3 2,4-Dichlorophe nylacetic acid (SUR) 20.98 4 Dicamba 21.10 5 Dichlorprop 21.46 6 4,4'-Dibromooc tafluorobipheny

l (IS) 21.53 7 2,4-D 21.64 8 Pentachlorophenol 21.81 9 Silvex 22.03 10 2,4,5-T 22.27 11 2,4-DB 22.51 12 Chloramben 22.55 13 Dinoseb 22.94 14 Bentazon 23.17 15 Dacthal 23.30 16 Quinclorac 23.55 17 Picloram 23.82 18 Acifluorfen 25.90

Conventional Primary Column: DB-1701, 30 m x 0.250 mm i.d., 0.25 μ m film thickness, injector te mp. 200 oC, liner

2 mm straight deactivat ed, inject ion volume 1 μ L of 100 ng/mL (highest level component) standard, splitless injecti on hold to .5 min then purge @ 30 mL/min, detect or temp 290 oC, detecto r mak e upgas P-5at 60 mL/ minu te. Tempera

tur e pr ogram: 45 oC initi

al, hold 10 min then program at 5 oC/minute to 70 oC, Then 30 oC/minute to 260 oC, and Hold for 5 min, Data c ollection via T urbochro m 4.1
Carri er gas: Helium (

UHP)

Detector ma

keup gas: 5% metha

ne/a rgon ( UHP)515.4-32

TABLE 4: DETECTION LIMITS IN REAGENT WATER

Compound Fortification

Level (ug/L) Primary

Column Detection Limita(ug/L) Secondary

Column Detection Limita(ug/L) Dalapon 0.100 0.054 0.074 3,5-Dichlorobenz

oic acid 0.050 0.212 0.049 Dicamba 0.050 0.032 0.042 Dichlorprop 0.100 0.433 0.12 2,4-D 0.100 0.055 0.066 Pentachlorophenol 0.010 0.014 0.084 Silvex 0.025 0.033 0.018 2,4,5-T 0.025 0.024 0.033 2,4-DB 0.100 0.246 0.182 Chloramben 0.050 0.057 0.083 Dinoseb 0.100 0.166 0.081 Bentazon 0.100 0.064 0.185 Dacthal 0.050 0.113 0.105 Quinclorac 0.050 0.080 0.113 Picloram 0.050 0.076 0.055 Acifluorfen 0.250 0.307 0.092

aDetection Limits were extracted and analyzed over 3 da ys for 9 replicates following the procedure outlined in Section 9.515.4-33

TABLE 5: LOW LEVEL PREC ISION AND ACCURAC Y IN REAGENT WATER

Compound Fortification Level (ug/L) Mean %

Recovery % RSD

(n=7) S/N Ratio a Dalapon 1.0 108 2.2 578 3,5-Dichlorobenz

oic acid 0.50 117 16 9 Dicamba 0.50 97 3.7 35 Dichlorprop 1.0 95 5.7 19 2,4-D 1.0 98 5.2 23 Pentachlorophenol 0.10 76 7.4 21 Silvex 0.25 84 20 9 2,4,5-T 0.25 96 7.3 16 2,4-DB 1.0 97 8.4 6 Chloramben 0.50 90 9.0 113 Dinoseb 1.0 103 6.7 8 Bentazon 1.0 100 2.1 41 Dacthal 0.50 92 6.5 100 Quinclorac 0.10 106 9.3 20 Picloram 1.0 92 2.6 23 Acifluorfen 0.50 77 5.9 80 2,4-Dichlorophenylacetic acid (SUR) 25 104 8.0

-

a Signal-to-noise ratios were calculated for each target compound pea k by dividing the peak height for each compound by the peak-to-pe ak noise, which was determined for each component from the method blank over a period of time equal to the full peak width in the target analyte’s retention time window.515.4-34

TABLE 6: MID LEVEL PR ECISION AND ACCUR ACY IN REAGENT WA TER

Compound Fortification Level (ug/L) Mean %

Recovery % RSD

(n=7) Dalapon 10 107 2.3 3,5-Dichlorobenz

oic acid 5.0 96 2.3 Dicamba 5.0 102 1.5 Dichlorprop 10 107 0.6 2,4-D 10 106 1.4 Pentachlorophenol 1.0 103 1.4 Silvex 2.5 107 4.4 2,4,5-T 2.5 105 1.3 2,4-DB 10 93 1.6 Chloramben 5.0 105 2.9 Dinoseb 10 119 4.6 Bentazon 10 98 0.7 Dacthal 5.0 100 1.9 Quinclorac 1.0 101 2.9 Picloram 10 99 3.1 Acifluorfen 5.0 107 4.5 2,4-Dichlorophenylacetic acid (SUR) 25 112 1.3515.4-35

TABLE 7: LOW LEVEL PREC ISION AND ACCURAC Y IN FORTIFIED C

HLORINATED SURFACE WATER

Compound Fortification Level (ug/L) Mean %

Recovery % RSD

(n=7) Dalapon 1.0 104 2.1 3,5-Dichlorobenz

oic acid 0.50 110 3.0 Dicamba 0.50 93 4.4 Dichlorprop 1.0 93 11 2,4-D 1.0 97 5.2 Pentachlorophenol 0.10 86 3.2 Silvex 0.25 103 4.3 2,4,5-T 0.25 100 3.5 2,4-DB 1.0 104 5.9 Chloramben 0.50 93 2.0 Dinoseb 1.0 99 1.2 Bentazon 1.0 91 2.2 Dacthal 0.50 92 4.6 Quinclorac 0.10 96 15 Picloram 1.0 102 2.4 Acifluorfen 0.50 98 4.1 2,4-Dichlorophenylacetic acid (SUR) 25 107 1.5515.4-36

TABLE 8: MID LEVEL PR ECISION AND ACCUR ACY IN FORTIFI

ED CHLORINATED SURFACE WATER

Compound Fortification Level (ug/L) Mean %

Recovery % RSD

(n=7) Dalapon 10 100 2.5 3,5-Dichlorobenz

oic acid 5.0 104 2.6 Dicamba 5.0 102 2.9 Dichlorprop 10 101 1.2 2,4-D 10 101 1.2 Pentachlorophenol 1.0 100 1.0 Silvex 2.5 101 1.0 2,4,5-T 2.5 100 1.6 2,4-DB 10 101 2.3 Chloramben 5.0 102 2.6 Dinoseb 10 101 1.6 Bentazon 10 98 1.8 Dacthal 5.0 99 2.0 Quinclorac 1.0 105 2.5 Picloram 10 107 3.2 Acifluorfen 5.0 92 2.4 2,4-Dichlorophenylacetic acid (SUR) 25 106 1.4515.4-37

TABLE 9: LOW LEVEL PREC ISION AND ACCURAC Y IN FORTIFIED C

HLORINATED GROUND WATER

Compound Fortification Level (ug/L) Mean %

Recovery % RSD

(n=7) Dalapon 1.0 105 1.5 3,5-Dichlorobenz

oic acid 0.50 104 6.0 Dicamba 0.50 100 2.2 Dichlorprop 1.0 109 3.5 2,4-D 1.0 108 10 Pentachlorophenol 0.10 103 17 Silvex 0.25 96 3.0 2,4,5-T 0.25 91 3.4 2,4-DB 1.0 94 3.1 Chloramben 0.50 88 2.7 Dinoseb 1.0 100 4.0 Bentazon 1.0 101 2.8 Dacthal 0.50 62 a 9.9 Quinclorac 0.10 107 5.7 Picloram 1.0 97 2.8 Acifluorfen 0.50 92 4.2 2,4-Dichlorophenylacetic acid (SUR) 25 95 3.1

aDacthal was present in the chlorinated surface water at about 1/5th the fortification lev el. Thi s wa s ta ken int o acc oun t in the det erm ina tio n of the Mean % Re cov ery.515.4-38

TABLE 10: MID LEVEL P RECISION AND ACCU RACY IN FORTIF

IED CHLORINATED GROUND WATER

Compound Fortification Level (ug/L) Mean %

Recovery % RSD

(n=7) Dalapon 10 97 5.5 3,5-Dichlorobenz

oic acid 5.0 95 2.1 Dicamba 5.0 98 1.6 Dichlorprop 10 79 0.7 2,4-D 10 99 1.6 Pentachlorophenol 1.0 100 4.2 Silvex 2.5 97 1.6 2,4,5-T 2.5 97 1.5 2,4-DB 10 92 1.1 Chloramben 5.0 102 2.6 Dinoseb 10 105 2.6 Bentazon 10 101 1.8 Dacthal 5.0 99 1.2 Quinclorac 1.0 94 1.5 Picloram 10 103 2.5 Acifluorfen 5.0 84 2.5 2,4-Dichlorophenylacetic acid (SUR) 25 106 1.1515.4-39

TABLE 11. SAMPLE HOLDING TIME DATA FOR SAMPLES FROM A

CHLORINATED SURFA CE WATER FORTIFI

ED WITH METHOD ANALYTES a

Compound Day 0 % Rec Day 2

% Rec Day 7

% Rec Day 14

% Rec Dalapon 91 90 91 108 3,5-Dichlorobenz

oic acid 98 97 85 91 Dicamba 92 92 96 99 Dichlorprop 89 88 91 95 2,4-D 88 85 87 92 Pentachlorophenol 92 85 86 93 Silvex 91 88 86 94 2,4,5-T 89 89 85 91 2,4-DB 87 84 86 93 Chloramben 86 86 88 100 Dinoseb 105 95 99 111 Bentazon 91 87 95 99 Dacthal 92 91 86 94 Quinclorac 90 80 84 91 Picloram 94 85 85 99 Acifluorfen 109 96 103 123

aAll samples fortified at the same level used to collect the mid level precision and accuracy data (see Table 10 for e xample).515.4-40

TABLE 12. EXTRACT HOLDING TIME DATA FOR SAMPLES FROM A

CHLORINATED SURFA CE WATER FORTIFI ED WITH METHOD ANALYTES a,b

Compound Initial a, b Injection %Rec Day 21

Reinjection %Rec Dalapon 100 89 3,5-Dichlorobenz

oic acid 104 113 Dicamba 102 104 Dichlorprop 100 101 2,4-D 101 102 Pentachlorophenol 100 102 Silvex 101 103 2,4,5-T 99 102 2,4-DB 101 102 Chloramben 102 105 Dinoseb 99 81 Bentazon 98 100 Dacthal 99 103 Quinclorac 105 127 Picloram 107 98 Acifluorfen 92 104 2,4-Dichlorophenyl

acetic acid (SUR) 106 105

a Sample storage s

tability is expressed as a percent recovery (%Rec) value calculated as described in Section 9.9.2.

bAll samples fortified at the same level used to collect the mid level precision and accuracy data (see Table 10 for e xample).515.4-41

TABLE 13: INITIAL DEMO NSTRATION OF CAP

ABILITY (IDC) REQUI REMENTS

Method Reference Requirement Specification and Frequency Acceptance Cri teria

Section 9.2.1 Initial

Demonstration of Low Method Background Analyze LRB prior to any

other IDC steps Demonstrate that all target analytes are below 1 /3 the reporting limit or lowest CAL standard, and tha

t possible interference from extraction media do not prevent the identification and quantification of method analytes. Section 9.2.2 Initial

Demonstration of Precision (ID

P) Analyze 4-7 replicate LFBs fortified a t midrange concentration. %RSD must be # 20%

Section 9.2.3 Initial

Demonstration of Accuracy Calculate average recovery

for replicates used in IDP Mean recovery must be within ± 20% of true value.

Section 9.2.4 Detection Lim it Determination Over a period of three days, prepare a minimum of 7 replicate L

FBs fortified a

t a concentration e

stimated to be near the Detection Limit. Analyze the replicates through all steps of the analysis. Calculate the Detection Limit using the equation in Section 9.2.4. Must be # 1/3 of the estab lish ed MRL.
Note: Data from Detection Limit replicates are not required to meet method precision and accuracy criteria. If the Detec

tion Limit replicates are fortified at a low enough concen

tration, it is likely that they will not meet precision and accuracy criteria.515.4-42

TABLE 14: QUALITY CONTROL REQUIREMENTS (SUMMARY)

Method Referenc e Requirement Specification and Frequency Acceptance Cri teria

Section 10.2 Initial Calibration Use internal standard calibration tech

nique to generate a calibration curve. Use at least 5 standard concentrations. When each calibration standard is calculated as an unknown using the calibration curve, the result must be 70-130% of the true value for all except the lowest standard, which must be 50-150% of the true value. Section 9.4 Laboratory

Reagent Blank (LRB) Daily, or with each

extraction batch of up to 20 samples, whichever is more frequent. Demonstrate that all target analytes are below 1 /3 the method reporting limit or lowest CAL standard, and that possible interferences do not prevent quantification of method analy

tes. If targets exceed 1 /3 the MR L, results for all sub

ject analy tes in extraction batch are invalid. Sections 9.5 and 10.3 Continuing

Calibration Check (CCC) Verify initial calibration by

analyzing a calibration standard at the beginning of each analy

sis batch prior to analyzing samples, after every 10 samples, and after the last sample.
Low CCC - near M

RL Mid CCC - near midpoin t in initial calibration curve High CCC - near hig

hest calibration standard 1) The result for each analy

te must be 70-130% of the true value for all but th

e lowest standard. The lowest standard must be 50-150% of the true value. 2) The peak area of internal standards must be 50-150% of the average peak area calculated during the initial calibration. Results for analytes that do not meet IS criteria or are not bracketed by

acceptable CCCs are invalid.515.4-43

TABLE 14: QUALITY CONTROL REQUIREMENTS (SUMMARY)

Method Reference Requirement Specification and Frequency Acceptance Cri teria

Section 9.7 Internal

Standard (IS) 4,4'-dibromooctafluorobiphenyl is added to the extraction solvent. Peak area count s for the IS in L

FBs, LRBs, and sample extracts must be within 50-150% of the average peak area calculated during the initial calibration. If the IS does not meet criteria, corr

esponding targ

et results are invalid. Section 9.8 Surrogate

Standard (SUR) 2,4-dichlorophe nylacetic acid is added to al

l calibration standards and samples, including QC samples. Surrogate recovery must be 70-130% of the true value. If surrog ate fails this criterion, report all results for sam ple as s usp ect/su rro gate reco very.
Section 9.9 Laboratory

Fortified Sample Matrix (LFM) and Laboratory Fortified Matrix Duplicate (LFMD) Analyze one LFM per

analysis batch (20 samples or less) fortified with method analy

tes at a concentration close to but greater than the native concentration. LFMD should be

used in place of Field D

uplicate if frequency of detects for targets is low. Recoveries at mid and high levels not within 70-130% or low-level recoveries not within 50-150% of the fortified amount m

ay indicate

a matrix effect. Target analy

te RPDs for LF

MD should be within ±30% at mid and high levels of fo

rtification and w

ithin ±50% near MRL.

Section 9.10 Field

Duplicates (FD) Extract and analyze at

least one FD with each extraction batch (20 samples or less). A LFMD may be substituted for a FD when the frequency of detects for target analytes is low. Target analyte RPDs for FD should be within ±30% at mid and high levels of fortification and within ±50% near MRL.

Section 9.11 Quality

Control Sample (QCS) Analyzed when new

Primary Dilution Standards (PDS) are prepared. Results must be 70-130% of the expected value.Method

Reference Requirement Specification and Frequency Acceptance Cri teria

515.4-44 Section 8.4 Sample

Holding Time 14 days with a ppropriate preservation and storage Sample results are valid only if samples are extra

cted within sample hold time. Section 8.4 Extract

Holding Time 21 days with a ppropriate storage Sample results are valid only if extracts are analyzed within extract hold time.515.4-45 FIGURE 1 CHROMATOGRAM OF THE CHLORPHENOXY HERBICIDES ON A RTX-1701 COLUMN

CHROMATOGRAPHIC C ONDITIONS ARE

GIVEN IN TABLE 1

.515.4-46 FIGURE 2 CHROMATOGRAM OF THE CHLORPHENOXY HERBICIDES ON A DB-5 COLUMN

CHROMATOGRAPHIC C ONDITIONS ARE

GIVEN IN TABLE 2.515.4-47 FIGURE 3 CHROMATOGRAM OF THE CHLORPHENOXY HERBICIDES ON A CONVENTIONAL PRIMARY COLUMN

(30 m x 250 um) CHR

OMATOGRAPHIC COND ITIONS ARE GI

VEN IN TABLE 3

.515.4-48 FIGURE 4
DIAZOMETHANE GEN ERATOR