METHOD 8020A

AROMATIC VOLATILE ORGANICS BY GAS CHROMATOGRAPHY

1.0 SCOPE AND APPLICATION

1.1 Method 8020 is used to determine the concentration of various

aromatic volatile organic compounds. The following compounds can be determined

by this method:

Appropriate Technique

Direct

Compound Name CAS No. a Purge-and-Trap Injection

Benzene 71-43-2 b b

Chlorobenzene 108-90-7 b b

1,2-Dichlorobenzene 95-50-1 b b

1,3-Dichlorobenzene 541-73-1 b b

1,4-Dichlorobenzene 106-46-7 b b

Ethylbenzene 100-41-4 b b

Toluene 108-88-3 b b

Xylenes b b

a Chemical Abstract Services Registry Number.

b adequate response by this technique.

1.2 Table 1 lists the method detection limit for each target analyte in

organic-free reagent water. Table 2 lists the estimated quantitation limit (EQL)

for other matrices.

2.0 SUMMARY OF METHOD

2.1 Method 8020 provides chromatographic conditions for the detection of

aromatic volatile compounds. Samples can be introduced into the GC using direct

injection or purge-and-trap (Method 5030). Ground water samples must be

determined using Method 5030. A temperature program is used in the gas

chromatograph to separate the organic compounds. Detection is achieved by a

photo-ionization detector (PID).

2.2 If interferences are encountered, the method provides an optional gas

chromatographic column that may be helpful in resolving the analytes from the

interferences and for analyte confirmation.

3.0 INTERFERENCES

3.1 Refer to Method 5030 and 8000.

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3.2 Samples can be contaminated by diffusion of volatile organics

(particularly chlorofluorocarbons and methylene chloride) through the sample

container septum during shipment and storage. A field sample blank prepared from

organic-free reagent water and carried through sampling and subsequent storage

and handling can serve as a check on such contamination.

4.0 APPARATUS AND MATERIALS

4.1 Gas chromatograph

4.1.1 Gas Chromatograph - Analytical system complete with gas

chromatograph suitable for on-column injections or purge-and-trap sample

introduction and all required accessories, including detectors, column

supplies, recorder, gases, and syringes. A Data system for measuring peak

heights and/or peak areas is recommended.

4.1.2 Columns

4.1.2.1 Column 1: 6 ft x 0.082 in ID #304 stainless steel

or gl ass col umn packed with 5% SP-1200 and 1. 75% Bentone-34 on

100/120 mesh Supelcoport, or equivalent.

4.1.2.2 Column 2: 8 ft x 0.1 in ID stainless steel or

glass column packed with 5% 1,2,3-Tris(2-cyanoethoxy)propane on

60/80 mesh Chromosorb W-AW, or equivalent.

4.1.3 Detector - Photoionization (PID) (h-Nu Systems, Inc. Model

PI-51-02 or equivalent).

4.2 Sample introduction apparatus Refer to Method 5030 for the

appropriate equipment for sample introduction purposes.

4.3 Syringes - A 5 mL Luerlok glass hypodermic and a 5 mL, gas-tight with

shutoff valve.

4.4

stoppers.

Volumetric flask, Class A - Appropriate sizes with ground glass

4.5 Microsyringe - 10 and 25 ~L with a 0.006 in ID needle (Hamilton 702N

or equival ent) and a 100 ~L.

4.6 Analytical balance - O.OODI g.

5.0 REAGENTS

5.1 Organic-free reagent water. All references to water in this method

refer to organic-free reagent water, as defined in Chapter One.

5.2 Methanol (CH30H) - pesticide quality or equivalent. Store away from

other solvents.

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5.3 Stock standards - Stock solutions may be prepared from pure standard

materials or purchased as certified solutions. Prepare stock standards in

methanol using assayed liquids. Because of the toxicity of benzene and

1,4-dichlorobenzene, primary dilutions of these materials should be prepared in

a hood.

5.3.1 Place about 9.8 mL of methanol in a 10 mL tQred ground glass

stoppered volumetric flask. Allow the flask to stand, ~nstoppered, for

about 10 min or until all alcohol wetted surfaces have dried. Weigh the

flask to the nearest 0.0001 g.

5.3.2 Using a 100 ~L syringe, immediately add two or more drops of

assayed reference material to the flask; then reweigh. The liquid must

fall directly into the alcohol without contacting the neck of the flask.

5.3.3 Reweigh, dilute to volume, stopper, and then mix by inverting

the flask several times. Calculate the concentration in milligrams per

liter (mg/L) from the net gain in weight. When compound purity is assayed

to be 96% or greater, the weight may be used without correction to

calculate the concentration of the stock standard. Commercially prepared

stock standards may be used at any concentration if they are certified by

the manufacturer or by an independent source.

5.3.4 Transfer the stock standard solution into a Teflon-sealed

screw-cap bottle. Store, with minimal headspace, at 4°C and protect from

light.

5.3.5 All standards must be replaced after 6 months, or sooner if

comparison with check standards indicates a problem.

5.4 Secondary dilution standards: Using stock standard solutions,

prepare in methanol secondary dilution standards, as needed, that contain the

compounds of interest, either singly or mixed together. The secondary dilution

standards should be prepared at concentrations such that the aqueous calibration

standards prepared in Section 5.5 will bracket the working range of the

analytical system. Secondary dilution standards should be stored with minimal

headspace for volatiles and should be checked frequently for signs of degradation

or evaporation, especially just prior to preparing calibration standards from

them.

5.5 Cali~ration standards: Calibration standards at a mlnlmum of five

concentrations are prepared in organic-free reagent water from the secondary

di 1uti on of the stock standards. One of the concentrati ons shoul d be at a

concentration near, but above, the method detection limit. The remaining

concentrations should correspond to the expected range of concentrations found

in real samples or should define the working range of the GC. Each standard

should contain each analyte for detection by this method (e.g., some or all of

the compounds listed in the target analyte list may be included). In order to

prepare accurate aqueous standard solutions, the following precautions must be

observed.

5.5.1 Do not inject more than 20 ~L of alcoholic standards into

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100 mL of organic-free reagent water.

5.5.2 Use a 25 ~L Hamilton 702N microsyringe or equivalent

(variations in needle geometry will adversely affect the ability to

deliver reproducible volumes of methanolic standards into water).

5.5.3 Rapidly inject the alcoholic standard into the filled

volumetric flask. Remove the needle as fast as possible after injection.

5.5.4 Mix aqueous standards by inverting the flask three times only.

5.5.5 Fill the sample syringe from the standard solution contained

in the expanded area of the flask Cdo not use any solution contained in

the neck of the flask).

5.5.6 Never use pipets to dilute or transfer samples or aqueous

standards.

5.5.7 Aqueous standards are not stable and should be discarded after

1 hr, unless properly sealed and stored. The aqueous standards can be

stored up to 24 hr, if held in sealed vials with zero headspace.

5.6 Internal standards (if internal standard calibration is used): To

use this approach, the analyst must select one or more internal standards that

are similar in analytical behavior to the compounds of interest. The analyst

must further demonstrate that the measurement of the internal standard is not

affected by method or matrix interferences. Because of these limitations, no

internal standard can be suggested that is ~pplicable to all samples.

Alpha , alp ha, alp ha-t r i fl u0 rot 0 1uene has been useds uccessfull y as an internal

standard.

5. 6. 1 Pre par e cali bra t i on standar ds at a rm n1murn of f i ve

concentrations for each parameter of interest as described in Section 5.5.

5.6.2 Prepare a spiking solution containing each of the internal

standards using the procedures described in Sections 5.3 and 5.4. It is

recommended that the secondary dilution standard be prepared at a

concentration of 15 mg/L of each internal standard compound. The addition

of 10 ~L of this standard to 5.0 mL of sample or calibration standard

would be equivalent to 30 ~g/L.

5.6_3 Analyze each calibration standard according to Section 7.0,

adding 10 ~L of internal standard spiking solution directly to the

syringe.

5.7 Surrogate standards: The analyst should monitor both the performance

of the analytical system and the effectiveness of the method in dealing with each

sample matrix by spiking each sample, standard, and organic-free reagent water

blank with surrogate compounds Cbromochlorobenzene, bromofluorobenzene. 1,1.1-

t r i flu 0 rot 0 1uene , flu 0 robenzen e, and di flu 0 robenzen earerec0 mm ended) whi ch

encompass the range of the temperature program used in this method. From stock

standard solutions prepared as in Section 5.3, add a volume to give 750 ~g of

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each surrogate to 45 mL of organic-free reagent water contained in a 50 mL

volumetric flask, mix, and dilute to volume for a concentration of 15 ng/~L. Add

10 ~L of this surrogate spiking solution directly into the 5 mL syringe with

every sample and reference standard analyzed. If the internal standard

calibration procedure is used, the surrogate compounds may be added directly to

the internal standard spiking solution (Section 5.6.2).

6.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING

6.1 See the introductory material to this chapter, Organic Analytes,

Section 4.1.

7.0 PROCEDU RE

7.1 Volatile compounds are introduced into the gas chromatograph either

by direct injection or purge-and-trap (Method 5030). Method 5030 may be used

directly on ground water samples or low-concentration contaminated soils and

sediments. For medium-concentration soils or sediments, methanolic extraction,

as described in Method 5030, may be necessary prior to purge-and-trap analysis.

Method 5030 also provides guidance on the analysis of aqueous miscible and nonaqueous miscible liquid wastes (see Section 7.4.1.1 below).

7.2 Gas chromatography conditions (Recommended):

7.2.1 Column 1:

Carrier gas (He) flow rate:

For lower boiling compounds:

Initial temperature:

Temperature program:

For higher boiling range of

Initial temperature:

Temperature program:

36 mL/mi n

50°C, hold for 2 min;

50°C to 90°C at 6 a C/min, hold until

all compounds have eluted.

compounds:

50°C, hold for 2 min;

50°C to 110 DC at 3 DC/min, hold until

all compounds have eluted.

Col umn 1 provides outstanding separations for a wide variety of

aromatic hydrocarbons. Column 1 should be used as the primary analytical

column because of its unique ability to resolve para-. meta-, and orthoaromatic isomers.

7.2.2 Column 2:

Carrier gas \He) flow rate:

Initial temperature:

Temperature program:

30 mu mi n

40°C, hold for 2 min;

40°C to 100 DC at 2 DC/min, hold until

all compounds have el uted.

Column 2, an extremely high polarity column, has been used for a

number of years to resolve aromatic hydrocarbons from alkanes in complex

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samples. However. because resolution between some of the aromatics is not

as efficient as with Column 1. Column 2 should be used ~s a confirmatory

column.

7.3 Calibration: Refer to Method 8000 for proper calibration techniques.

Use Table 1 and especially Table 2 for guidance on selecting the lowest point on

the calibration curve.

7.3.1 Calibration must take place using the same sample introduction

method that will be used to analyze actual samples (see Section 7.4.1).

7.3.2 The procedure for internal or external calibration may be

used. Refer to Method 8000 for a description of each of these procedures.

7.4 Gas chromatographic analysis:

7.4.1 Introduce volatile compounds into the gas chromatograph using

either Method 5030 (purge-and-trap method) or the direct injection method.

If the internal standard calibration technique is used, add 10 ~L of

internal standard to the sample prior to purging.

7. 4. 1. 1 0ire ctinj ect i on: In ve ry 1i mit ed app1i cati ons

(e.g., aqueous process wastes), direct injection of the sample into

the GC system with a 10 ~L syringe may be appropriate. The

detection limit is very high (approximately 10,000 ~gjL)~ therefore,

it is only permitted when concentrations in excess of 10,000 ~g/L

are expected or for water soluble compounds that do not purge. The

system must be calibrated by direct injection (bypassing the purgeand-trap device).

Non-aqueous miscible wastes may also be analyzed by direct

injection if the concentration of target analytes in the sample

falls within the calibration range. If dilution of the sample is

necessary, follow the guidance for High Concentration samples in

Method 5030, Section 7.3.3.2.

7.4_2 Method 8000 provides instructions on the analysis sequence,

appropriate dilutions, establishing daily retention time windows, and

identification criteria. Include a mid-concentration standard after each

group of 10 samples in the analysis sequence.

7.4.3 Table 1 summarizes the estimated retention times and detection

limits for a number of organic compounds ana1yzable using this method. An

example of the separation achieved by Column 1 is shown in Figure 1.

Figure 2 shows an example of the separation achieved using Column 2.

7.4.4 Record the sample volume purged or injected and the resulting

peak sizes (in area units or peak heights).

7.4.5 Calculation of concentration is covered in Method 8000.

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7.4.6 If analytical interferences are suspected, or for the purpose

of confirmation, analysis using the second GC column is recommended.

7.4.7 If the response for a peak is off scale, i.e., beyond the

calibration range of the standards, prepare a dilution of the sample with

organic-free reagent water. The dilution must be performed on a second

aliquot of the sample which has been properly sealed and stored prior to

use.

8.0 QUALITY CONTROL

8.1 Refer to Chapter One for specific quality control procedures and

Method 8000 for gas chromatographic procedures. Quality control to ensure the

proper operation of the purge-and-trap device is covered in Method 5030.

8.2 Quality control required to validate the GC system operation lS found

in Method 8000.

8.2.1 The quality control check sample concentrate (Method 8000)

should contain each parameter of interest at a concentration of 10 mg/L

in methanol.

8.2.2 Table 3 indicates the calibration and QC acceptance criteria

for this method. Table 4 gives method accuracy and precision as functions

of concentration for the analytes of interest. The contents of both

tables should be used to evaluate a laboratory's ability to perform and

generate acceptable data by this method.

8.3 Calculate surrogate standard recovery on all samples, blanks, and

spikes. Determine if recovery is within limits (limits established by performing

OC procedure outlined in Method 8000).

8.3.1 If recovery is not within limits, the following is required.

Check to be sure that there are no errors in

calculations, surrogate solutions and internal

standards. Also, check instrument performance.

Recalculate the data and/or reanalyze the extract if any

of the above checks reveal a problem.

Reextract and reanalyze the sample if none of the above

are a problem or flag the data as "estimated

concentration" .

9.0 METHOD PERFORMANCE

9.1 This method was tested by 20 laboratories using organic-free reagent

water, drinking water, surface water, and three industrial wastewaters spiked at

six concentrations over the range 2.1 - 500 ~g/L. Single operator precision,

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overall pr.eci st on, and method accuracy were found to be directly related to the

concentration of the parameter and essentially independent of the sample matrix.

Linear equations to describe these relationships are presented in Table 4.

9.2 The accuracy and precision obtained will be determined by the sample

matrix. sample introduction technique, and by the calibration procedure used.

9.3 The method detection limits reported in Table 1 were generated under

optimum analytical conditions by an Agency contractor (Ref. 7) as guidance, and

may not be readily achievable by all laboratories at all times.

10.0 REFERENCES

1. Bell~r, T_A., and J.J. Lichtenberg, J. Amer. Water Works Assoc .• 66(12),

pp. 739-744, 1974.

2. Bellar, T.A., and J.J. Lichtenberg, "Semi-Automated Headspace Analysis of

Drinking Waters and Industrial Waters for Purgeable Volatile Organic

Compounds". in Van Hall (ed.), Measu(ement of Organic Pollutants in Water

and Wastewater, ASTM STP 686, pp. 108-129, 1979.

3. Dowty, B.J., S.R. Antoine, and J.L. Laseter, "Quantitative and Qualitative

Ana lysi s of Purgeabl e. Organi cs by Hi gh Resol uti on Gas Chromatography and

Flame Ionization Detection". in Van Hall, ed., Measurement of Organic

Pollutants in Water and Wastewater. ASTM STP 686, pp. 24-35, 1979.

4. Development and Applicatioh of Test Procedures for Specific Organic Toxic

Substances in Wastewaters. Category 11 - Purgeables and Category 12 -

Acrolein, Acrylo.nitrile, and Dichlorodifluoromethane. Report for EPA

Contract 68-03-2635.

5. "EPA Method Validation Study 24, Method 602 (Purgeable Aromatics)", report

for EPA Contract 68-03-2856.

6. U.S. EPA 40 CFR Part 136, "Guidelines Establishing Test Procedures for the

Analysis of Pollutants Under the Clean Water Act; Final Rule and Interim

Final Rule and Proposed Rule", October 26~ 1984.

7. Gebhart. J.E., S.V. Lucas, S.J. Naber, A.M. Berry, T.H. Danison and H.M.

Burkholder, "Validation of SW-846 Methods 8010, 8015, and 8020"; Report

for EPA Contract 68-03-1760, Work Assignment 2-15; US EPA, EMSLCincinnati, 1987."

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TABLE 1.

CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION LIMITS

FOR AROMATIC VOLATILE ORGANICS

Retention time Method

(min) detection

1t rm t"

Compound Co l . 1 Co 1 . 2 (~g/L)

Benzene 3.33 2.75 0.2

Chi or cbenz ene" 9.17 8.02 0.2

1,4-Dichlorobenzene 16.8 16.2 0.3

1,3-Dichlorobenzene 18.2 15.0 0.4

1,2-Dichlorobenzene 25.9 19.4 0.4

Ethyl Benzene 8.25 6.25 0.2

Toluene 5.75 4.25 0.2

Xylenes

a Using purge-and-trap method (Method 5030). See Sec. 9.3.

b Chlorobenzene and m-xylene may co-elute on some columns.

TABLE 2.

DETERMINATION OF ESTIMATED QUANTITATION LIMITS (EQLs)

FOR VARIOUS MATRICES a

Matrix

Ground water

Low-concentration soil

Water miscible liquid waste

High-concentration soil and sludge

Non-water miscible waste

Factor

10

10

500

1250

1250

a EQL = [Method detection limit (see Table I)J X [Factor found in this

tableJ. For non-aqueous samples, the factor is on a wet-weight basis.

Sample EQLs are highly matrix-dependent. The EQLs determined herein are

provided for guidance and may not always be achievable.

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TABLE 3.

OC ACCEPTANCE CRITERIAa

Range Limit Rang£ Range

for 0 for s for x P, Ps

Parameter (~g/U (fJg/ U (fJg/U (% )

Benzene 15.4-24.6 4.1 10.0-27.9 39-150

Chlorobenzene 16.1-23.9 3.5 12.7-25.4 55-135

1,2-Dichlorobenzene 13.6-26.4 5.8 10.6-27.6 37-154

1,3-Dichlorobenzene 14.5-25.5 5.0 12.8-25.5 50-141

1,4-Dichlorobenzene 13.9-26.1 5.5 11.6-25.5 42-143

Ethylbenzene 12.6-27.4 6.7 10.0-28.2 32-160

Toluene 15.5-24.5 4.0 11 . 2-27.7 46-148

Q Concentration measured in QC check sample, in fJg/L.

s Standard deviation of four recovery measurements, in ~g/L.

x Average recovery for four recovery measurements, in ~g/L.

P, Ps Percent recovery measured.

a Criteria from 40 CFR Part 136 for Meth{)d 602, using packed columns, and

were calculated assuming a check sample concentration of 20 ~g/L. These

criteria are based directly upon the method performance data in Table 4.

Where necessary, the limits for recovery have been broadened to assure

applicability of the limits to concentrations below those used to develop

Table 1. When capillary columns are used, see Method 8021 for performance

data.

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TABLE 4.

METHOD ACCURACY AND PRECISION AS FUNCTIONS OF CONCENTRATION

Parameter

Benzene

Chlorobenzene

1,2-Dichlorobenzene

1,3-Dichlorobenzene

1,4-Dichlorobenzene

Ethylbenzene

Toluene

Accuracy, as

recovery, x·

(~g / l)

0.92C+0.57

0.95C+0.02

0.93C+0.52

0.96C-0.04

0.93C-0.09

0.94C+0.31

0.94C+0.65

Single analyst

precision, sr'

(~g/l)

0.09X+0.59

0.09x+0.23

0.lh.-0.04

0.15x.-0.10

o.15x.+0 . 28

0.17x.+0.46

0.09x+0.48

Overall

precision,

S' (~g/l)

O. 2lx.+0. 56

0.17x.+0.l0

0.22x.+0.53

0.19x.+0.09

0.20x.+0.41

0.26x.+0.23

O.18x+0. 71

x'

s . r

S'

C

x

Expected recovery for one or more measurements of a sample

containing concentration C, in ~g/L.

Expected single analyst st.andar d deviation of measurements at an

average concentration of x, in ~g/L.

Expected interlaboratory standa~d deviation of measurements at an

average concentration found of x, in ~g/L.

True value for the concentration, in ~g/L.

Average recovery found for measurements of samples containing a

concentration of C, in ~g/L.

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CD-ROM

Figure 1 Chromatogram of Aromatic Volatile Organics

(column 1 conditions)

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Figure 2

Chromatogram of Aromatic Volatile Organics

(column 2 conditions)

Column:

Program:

Detector:

Sample:

5% 1,2,3-Tris(2-Cyanoethoxy)Propane on Chromosorb-W

40°C-2 Minutes, 2°e/Min. to lOOoe

Photo ionization

2.0 pg/L Standard Mixture

J

>-

I )(

e I ..

J •

Q.

i

I

I

• j

'I I .i o .- I

I !

• 1

I IiI ... I £~f I i

i - Ii ..

j

"'. "'"

o 12 20

tlmNTlOH TIM. IIIINUTUJ

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METHOD 8020A

AROMATIC VOLATILE ORGANICS BY GAS CHROMATOGRAPHY

Start

.J

"'

,I,,-

7.1 Introduce compounds

into gas chromatograph 7.4.4 Record volume by direct injection or

purge-and-trap purged or injected

(Method 5030) and peak sizes.

'w- 'w7.2 Set gas 7.4.5 Calculate

chromatograph concentration

condition. (refer to Method 8000)

,W- I"

7.3 Celibrate

(refer to Method 8000) 7.4.6 Are

analytical Yes ... 7.4.6 Analyze using .. interferences II' second GC column. , suspectedi'

If'

No

7.4.1 Introduce

volatile compounds I"

into gas chromatograph

by purge-and-trap or

direct injection.

7.4.7 Is

response for Yes "" 7 .4.7 Dilute second a peak II' aliquot of sample.

,I" off-scalei' .

7.4.2 Follow Method

8000 for analysis I- No

sequence, ate.

'WStop

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