Section

[Code of Federal Regulations]

[Title 40, Volume 22]

[Revised as of July 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 40CFR136.5]

[Page 39-339]

TITLE 40--PROTECTION OF ENVIRONMENT

CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

PART 136_GUIDELINES ESTABLISHING TEST PROCEDURES FOR THE ANALYSIS OF

POLLUTANTS--Table of Contents

Sec. 136.5 Approval of alternate test procedures.

(a) The Regional Administrator of the region in which the discharge

will occur has final responsibility for approval of any alternate test

procedure proposed by the responsible person or firm making the

discharge.

(b) Within thirty days of receipt of an application, the Director

will forward such application proposed by the responsible person or firm

making the discharge, together with his recommendations, to the Regional

Administrator. Where the Director recommends rejection of the

application for scientific and technical reasons which he provides, the

Regional Administrator shall deny the application,

[[Page 40]]

and shall forward a copy of the rejected application and his decision to

the Director of the State Permit Program and to the Director of the

Analytical Methods Staff, Washington, DC.

proposed by the responsible person or firm making the discharge, the

Regional Administrator shall forward a copy of the application to the

Director of the Analytical Methods Staff, Washington, DC.

(d) Within ninety days of receipt by the Regional Administrator of

an application for an alternate test procedure, proposed by the

responsible person or firm making the discharge, the Regional

Administrator shall notify the applicant and the appropriate State

agency of approval or rejection, or shall specify the additional

information which is required to determine whether to approve the

proposed test procedure. Prior to the expiration of such ninety day

period, a recommendation providing the scientific and other technical

basis for acceptance or rejection will be forwarded to the Regional

Administrator by the Director of the Analytical Methods Staff,

Washington, DC. A copy of all approval and rejection notifications will

be forwarded to the Director, Analytical Methods Staff, Washington, DC,

for the purposes of national coordination.

(e) Approval for nationwide use. (1) Within sixty days of the

receipt by the Director of the Analytical Methods Staff, Washington, DC,

of an application for an alternate test procedure for nationwide use,

the Director of the Analytical Methods Staff shall notify the applicant

in writing whether the application is complete. If the application is

incomplete, the applicant shall be informed of the information necessary

to make the application complete.

(2) Within ninety days of the receipt of a complete package, the

Analytical Methods Staff shall perform any analysis necessary to

determine whether the alternate method satisfies the applicable

requirements of this part, and the Director of the Analytical Methods

Staff shall recommend to the Administrator that he/she approve or reject

the application and shall also notify the applicant of such

recommendation.

(3) As expeditiously as practicable, an alternate method determined

by the Administrator to satisfy the applicable requirements of this part

shall be proposed by EPA for incorporation in subsection 136.3 of 40 CFR

part 136. EPA shall make available for review all the factual bases for

its proposal, including any performance data submitted by the applicant

and any available EPA analysis of those data.

(4) Following a period of public comment, EPA shall, as

expeditiously as practicable, publish in the Federal Register a final

decision to approve or reject the alternate method.

[38 FR 28760, Oct. 16, 1973, as amended at 41 FR 52785, Dec. 1, 1976; 55

FR 33440, Aug. 15, 1990; 62 FR 30763, June 5, 1997]

Appendix A to Part 136--Methods for Organic Chemical Analysis of

Municipal and Industrial Wastewater

Method 601--Purgeable Halocarbons

1. Scope and Application

1.1 This method covers the determination of 29 purgeable

halocarbons.

The following parameters may be determined by this method:

------------------------------------------------------------------------

STORET

Parameter No. CAS No.

------------------------------------------------------------------------

Bromodichloromethane........................... 32101 75-27-4

Bromoform...................................... 32104 75-25-2

Bromomethane................................... 34413 74-83-9

Carbon tetrachloride........................... 32102 56-23-5

Chlorobenzene.................................. 34301 108-90-7

Chloroethane................................... 34311 75-00-3

2-Chloroethylvinyl ether....................... 34576 100-75-8

Chloroform..................................... 32106 67-66-3

Chloromethane.................................. 34418 74-87-3

Dibromochloromethane........................... 32105 124-48-1

1,2-Dichlorobenzene............................ 34536 95-50-1

1,3-Dichlorobenzene............................ 34566 541-73-1

1,4-Dichlorobenzene............................ 34571 106-46-7

Dichlorodifluoromethane........................ 34668 75-71-8

1,1-Dichloroethane............................. 34496 75-34-3

1,2-Dichloroethane............................. 34531 107-06-2

1,1-Dichloroethane............................. 34501 75-35-4

trans-1,2-Dichloroethene....................... 34546 156-60-5

1,2-Dichloropropane............................ 34541 78-87-5

cis-1,3-Dichloropropene........................ 34704 10061-01-5

trans-1,3-Dichloropropene...................... 34699 10061-02-6

Methylene chloride............................. 34423 75-09-2

1,1,2,2-Tetrachloroethane...................... 34516 79-34-5

Tetrachloroethene.............................. 34475 127-18-4

1,1,1-Trichloroethane.......................... 34506 71-55-6

1,1,2-Trichloroethane.......................... 34511 79-00-5

Tetrachloroethene.............................. 39180 79-01-6

Trichlorofluoromethane......................... 34488 75-69-4

Vinyl chloride................................. 39715 75-01-4

------------------------------------------------------------------------

[[Page 41]]

1.2 This is a purge and trap gas chro ma tographic (GC) method

applicable to the determination of the compounds listed above in

municipal and industrial discharges as provided under 40 CFR 136.1. When

this method is used to analyze unfamiliar samples for any or all of the

compounds above, compound identifications should be supported by at

least one additional qualitative technique. This method describes

analytical conditions for a second gas chromatographic column that can

be used to confirm measurements made with the primary column. Method 624

provides gas chromatograph/mass spectrometer (GC/MS) conditions

appropriate for the qualitative and quantitative confirmation of results

for most of the parameters listed above.

1.3 The method detection limit (MDL, defined in Section 12.1)

¹ for each parameter is listed in Table 1. The MDL for a

specific wastewater may differ from those listed, depending upon the

nature of interferences in the sample matrix.

1.4 Any modification of this method, beyond those expressly

permitted, shall be considered as a major modification subject to

application and approval of alternate test procedures under 40 CFR 136.4

and 136.5.

1.5 This method is restricted to use by or under the supervision of

analysts experienced in the operation of a purge and trap system and a

gas chromatograph and in the interpretation of gas chromatograms. Each

analyst must demonstrate the ability to generate acceptable results with

this method using the procedure described in Section 8.2.

2. Summary of Method

2.1 An inert gas is bubbled through a 5-mL water sample contained in

a specially-designed purging chamber at ambient temperature. The

halocarbons are efficiently transferred from the aqueous phase to the

vapor phase. The vapor is swept through a sorbent trap where the

halocarbons are trapped. After purging is completed, the trap is heated

and backflushed with the inert gas to desorb the halocarbons onto a gas

chromatographic column. The gas chromatograph is temperature programmed

to separate the halocarbons which are then detected with a halide-

specific detector.^{2, 3}

2.2 The method provides an optional gas chromatographic column that

may be helpful in resolving the compounds of interest from interferences

that may occur.

3. Interferences

3.1 Impurities in the purge gas and organic compounds outgassing

from the plumbing ahead of the trap account for the majority of

contamination problems. The analytical system must be demonstrated to be

free from contamination under the conditions of the analysis by running

laboratory reagent blanks as described in Section 8.1.3. The use of non-

Teflon plastic tubing, non-Teflon thread sealants, or flow controllers

with rubber components in the purge and trap system should be avoided.

3.2 Samples can be contaminated by diffusion of volatile organics

(particularly fluorocarbons and methylene chloride) through the septum

seal ilto the sample during shipment and storage. A field reagent blank

prepared from reagent water and carried through the sampling and

handling protocol can serve as a check on such contamination.

3.3 Contamination by carry-over can occur whenever high level and

low level samples are sequentially analyzed. To reduce carry-over, the

purging device and sample syringe must be rinsed with reagent water

between sample analyses. Whenever an unusually concentrated sample is

encountered, it should be followed by an analysis of reagent water to

check for cross contamination. For samples containing large amounts of

water-soluble materials, suspended solids, high boiling compounds or

high organohalide levels, it may be necessary to wash out the purging

device with a detergent solution, rinse it with distilled water, and

then dry it in a 105[deg]C oven between analyses. The trap and other

parts of the system are also subject to contamination; therefore,

frequent bakeout and purging of the entire system may be required.

4. Safety

4.1 The toxicity or carcinogenicity of each reagent used in this

method has not been precisely defined; however, each chemical compound

should be treated as a potential health hazard. From this viewpoint,

exposure to these chemicals must be reduced to the lowest possible level

by whatever means available. The laboratory is responsible for

maintaining a current awareness file of OSHA regulations regarding the

safe handling of the chemicals specified in this method. A reference

file of material data handling sheets should also be made available to

all personnel involved in the chemical analysis. Additional references

to laboratory safety are available and have been identified

^4-6 for the information of the analyst.

4.2 The following parameters covered by this method have been

tentatively classified as known or suspected, human or mammalian

carcinogens: carbon tetrachloride, chloroform, 1,4-dichlorobenzene, and

vinyl chloride. Primary standards of these toxic compounds should be

prepared in a hood. A NIOSH/MESA approved toxic gas respirator should be

worn when the analyst handles high concentrations of these toxic

compounds.

[[Page 42]]

5. Apparatus and Materials

5.1 Sampling equipment, for discrete sampling.

5.1.1 Vial--25-mL capacity or larger, equipped with a screw cap with

a hole in the center (Pierce 13075 or equivalent). Detergent

wash, rinse with tap and distilled water, and dry at 105 [deg]C before

use.

5.1.2 Septum--Teflon-faced silicone (Pierce 12722 or

equivalent). Detergent wash, rinse with tap and distilled water, and dry

at 105 [deg]C for 1 h before use.

5.2 Purge and trap system--The purge and trap system consists of

three separate pieces of equipment: a purging device, trap, and

desorber. Several complete systems are now commercially available.

5.2.1 The purging device must be designed to accept 5-mL samples

with a water column at least 3 cm deep. The gaseous head space between

the water column and the trap must have a total volume of less than 15

mL. The purge gas must pass through the water column as finely divided

bubbles with a diameter of less than 3 mm at the origin. The purge gas

must be introduced no more than 5 mm from the base of the water column.

The purging device illustrated in Figure 1 meets these design criteria.

5.2.2 The trap must be at least 25 cm long and have an inside

diameter of at least 0.105 in. The trap must be packed to contain the

following minimum lengths of adsorbents: 1.0 cm of methyl silicone

coated packing (Section 6.3.3), 7.7 cm of 2,6-diphenylene oxide polymer

(Section 6.3.2), 7.7 cm of silica gel (Section 6.3.4), 7.7 cm of coconut

charcoal (Section 6.3.1). If it is not necessary to analyze for

dichlorodifluoromethane, the charcoal can be eliminated, and the polymer

section lengthened to 15 cm. The minimum specifications for the trap are

illustrated in Figure 2.

5.2.3 The desorber must be capable of rapidly heating the trap to

180 [deg]C. The polymer section of the trap should not be heated higher

than 180 [deg]C and the remaining sections should not exceed 200 [deg]C.

The desorber illustrated in Figure 2 meets these design criteria.

5.2.4 The purge and trap system may be assembled as a separate unit

or be coupled to a gas chromatograph as illustrated in Figures 3 and 4.

5.3 Gas chromatograph--An analytical system complete with a

temperature programmable gas chromatograph suitable for on-column

injection and all required accessories including syringes, analytical

columns, gases, detector, and strip-chart recorder. A data system is

recommended for measuring peak areas.

5.3.1 Column 1--8 ft long x 0.1 in. ID stainless steel or glass,

packed with 1% SP-1000 on Carbopack B (60/80 mesh) or equivalent. This

column was used to develop the method performance statements in Section

12. Guidelines for the use of alternate column packings are provided in

Section 10.1.

5.3.2 Column 2--6 ft long x 0.1 in. ID stainless steel or glass,

packed with chemically bonded n-octane on Porasil-C (100/120 mesh) or

equivalent.

5.3.3 Detector--Electrolytic conductivity or microcoulometric

detector. These types of detectors have proven effective in the analysis

of wastewaters for the parameters listed in the scope (Section 1.1). The

electrolytic conductivity detector was used to develop the method

performance statements in Section 12. Guidelines for the use of

alternate detectors are provided in Section 10.1.

5.4 Syringes--5-mL glass hypodermic with Luerlok tip (two each), if

applicable to the purging device.

5.5 Micro syringes--25-[micro]L, 0.006 in. ID needle.

5.6 Syringe valve--2-way, with Luer ends (three each).

5.7 Syringe--5-mL, gas-tight with shut-off valve.

5.8 Bottle--15-mL, screw-cap, with Teflon cap liner.

5.9 Balance--Analytical, capable of accurately weighing 0.0001 g.

6. Reagents

6.1 Reagent water--Reagent water is defined as a water in which an

interferent is not observed at the MDL of the parameters of interest.

6.1.1 Reagent water can be generated by passing tap water through a

carbon filter bed containing about 1 lb of activated carbon (Filtrasorb-

300, Calgon Corp., or equivalent).

6.1.2 A water purification system (Millipore Super-Q or equivalent)

may be used to generate reagent water.

6.1.3 Reagent water may also be prepared by boiling water for 15

min. Subsequently, while maintaining the temperature at 90 [deg]C,

bubble a contaminant-free inert gas through the water for 1 h. While

still hot, transfer the water to a narrow mouth screw-cap bottle and

seal with a Teflon-lined septum and cap.

6.2 Sodium thiosulfate--(ACS) Granular.

6.3 Trap Materials:

6.3.1 Coconut charcoal--6/10 mesh sieved to 26 mesh, Barnabey

Cheney, CA-580-26 lot M-2649 or equivalent.

6.3.2 2,6-Diphenylene oxide polymer--Tenax, (60/80 mesh),

chromatographic grade or equivalent.

6.3.3 Methyl silicone packing--3% OV-1 on Chromosorb-W (60/80 mesh)

or equivalent.

6.3.4 Silica gel--35/60 mesh, Davison, grade-15 or equivalent.

6.4 Methanol--Pesticide quality or equivalent.

6.5 Stock standard solutions--Stock standard solutions may be

prepared from

[[Page 43]]

pure standard materials or purchased as certified solutions. Prepare

stock standard solutions in methanol using assayed liquids or gases as

appropriate. Because of the toxicity of some of the organohalides,

primary dilutions of these materials should be prepared in a hood. A

NIOSH/MESA approved toxic gas respirator should be used when the analyst

handles high concentrations of such materials.

6.5.1 Place about 9.8 mL of methanol into a 10-mL ground glass

stoppered volumetric flask. Allow the flask to stand, unstoppered, for

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

flask to the learest 0.1 mg.

6.5.2 Add the assayed reference material:

6.5.2.1 Liquid--Using a 100 [micro]L syringe, immediately add two or

more drops of assayed reference material to the flask, then reweigh. Be

sure that the drops fall directly into the alcohol without contacting

the neck of the flask.

6.5.2.2 Gases--To prepare standards for any of the six halocarbons

that boil below 30 [deg] C (bromomethane, chloroethane, chloro methane,

dichlorodifluoromethane, trichlorofluoromethane, vinyl chloride), fill a

5-mL valved gas-tight syringe with the reference standard to the 5.0-mL

mark. Lower the needle to 5 mm above the methanol meniscus. Slowly

introduce the reference standard above the surface of the liquid (the

heavy gas will rapidly dissolve into the methanol).

6.5.3 Reweigh, dilute to volume, stopper, then mix by inverting the

flask several times. Calculate the concentration in [micro]g/[micro]L

from the net gain in weight. When compound purity is assayed to be 96%

or greater, the weight can be used without correction to calculate the

concentration of the stock standard. Commercially prepared stock

standards can be used at any concentration if they are certified by the

malufacturer or by an independent source.

6.5.4 Transfer the stock standard solution into a Teflon-sealed

screw-cap bottle. Store, with minimal headspace, at -10 to -20 [deg]C

and protect from light.

6.5.5 Prepare fresh standards weekly for the six gases and 2-

chloroethylvinyl ether. All other standards must be replaced after one

month, or sooner if comparison with check standards indicates a problem.

6.6 Secondary dilution standards--Using stock standard solutions,

prepare secondary dilution standards in methanol 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 7.3.1 or 7.4.1 will

bracket the working range of the analytical system. Secondary dilution

standards should be stored with minimal headspace and should be checked

frequently for signs of degradation or evaporation, especially just

prior to preparing calibration standards from them.

6.7 Quality control check sample concentrate--See Section 8.2.1.

7. Calibration

7.1 Assemble a purge and trap system that meets the specifications

in Section 5.2. Condition the trap overnight at 180 [deg]C by

backflushing with an inert gas flow of at least 20 mL/min. Condition the

trap for 10 min once daily prior to use.

7.2 Connect the purge and trap system to a gas chromatograph. The

gas chromatograph must be operated using temperature and flow rate

conditions equivalent to those given in Table 1. Calibrate the purge and

trap-gas chromatographic system using either the external standard

technique (Section 7.3) or the internal standard technique (Section

7.4).

7.3 External standard calibration procedure:

7.3.1 Prepare calibration standards at a miminum of three

concentration levels for each parameter by carefully adding 20.0

[micro]L of one or more secondary dilution standards to 100, 500, or

1000 [micro]L of reagent water. A 25-[micro]L syringe with a 0.006 in.

ID needle should be used for this operation. One of the external

standards should be at a concentration near, but above, the MDL (Table

1) and the other concentrations should correspond to the expected range

of concentrations found in real samples or should define the working

range of the detector. These aqueous standards can be stored up to 24 h,

if held in sealed vials with zero headspace as described in Section 9.2.

If not so stored, they must be discarded after 1 h.

7.3.2 Analyze each calibration standard according to Section 10, and

tabulate peak height or area responses versus the concentration in the

standard. The results can be used to prepare a calibration curve for

each compound. Alternatively, if the ratio of response to concentration

(calibration factor) is a constant over the working range (<10% relative

standard deviation, RSD), linearity through the origin can be assumed

and the average ratio or calibration factor can be used in place of a

calibration curve.

7.4 Internal standard calibration procedure--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 applicable to

all samples. The compounds recommended for use as surrogate spikes in

Section 8.7 have been used successfully as internal standards, because

of their generally unique retention times.

[[Page 44]]

7.4.1 Prepare calibration standards at a minimum of three

concentration levels for each parameter of interest as described in

Section 7.3.1.

7.4.2 Prepare a spiking solution containing each of the internal

standards using the procedures described in Sections 6.5 and 6.6. It is

recommended that the secondary dilution standard be prepared at a

concentration of 15 [micro]g/mL of each internal standard compound. The

addition of 10 [micro]L of this standard to 5.0 mL of sample or

calibration standard would be equivalent to 30 [micro]g/L.

7.4.3 Analyze each calibration standard according to Section 10,

adding 10 [micro]L of internal standard spiking solution directly to the

syringe (Section 10.4). Tabulate peak height or area responses against

concentration for each compound and internal standard, and calculate

response factors (RF) for each compound using Equation 1.

[GRAPHIC] [TIFF OMITTED] TC15NO91.094

Equation 1

where:

As=Response for the parameter to be measured.

Ais=Response for the internal standard.

Cis=Concentration of the internal standard.

Cs=Concentration of the parameter to be measured.

If the RF value over the working range is a constant (<10% RSD), the RF

can be assumed to be invariant and the average RF can be used for

calculations. Alternatively, the results can be used to plot a

calibration curve of response ratios, As/Ais, vs.

RF.

7.5 The working calibration curve, calibration factor, or RF must be

verified on each working day by the measurement of a QC check sample.

7.5.1 Prepare the QC check sample as described in Section 8.2.2.

7.5.2 Analyze the QC check sample according to Section 10.

7.5.3 For each parameter, compare the response (Q) with the

corresponding calibration acceptance criteria found in Table 2. If the

responses for all parameters of interest fall within the designated

ranges, analysis of actual samples can begin. If any individual Q falls

outside the range, proceed according to Section 7.5.4.

Note: The large number of parameters in Table 2 present a

substantial probability that one or more will not meet the calibration

acceptance criteria when all parameters are analyzed.

7.5.4 Repeat the test only for those parameters that failed to meet

the calibration acceptance criteria. If the response for a parameter

does not fall within the range in this second test, a new calibration

curve, calibration factor, or RF must be prepared for that parameter

according to Section 7.3 or 7.4.

8. Quality Control

8.1 Each laboratory that uses this method is required to operate a

formal quality control program. The minimum requirements of this program

consist of an initial demonstration of laboratory capability and an

ongoing analysis of spiked samples to evaluate and document data

quality. The laboratory must maintain records to document the quality of

data that is generated. Ongoing data quality checks are compared with

established performance criteria to determine if the results of analyses

meet the performance characteristics of the method. When results of

sample spikes indicate atypical method performance, a quality control

check standard must be analyzed to confirm that the measurements were

performed in an in-control mode of operation.

8.1.1 The analyst must make an initial, one-time, demonstration of

the ability to generate acceptable accuracy and precision with this

method. This ability is established as described in Section 8.2.

8.1.2 In recognition of advances that are occurring in

chromatography, the analyst is permitted certain options (detailed in

Section 10.1) to improve the separations or lower the cost of

measurements. Each time such a modification is made to the method, the

analyst is required to repeat the procedure in Section 8.2.

8.1.3 Each day, the analyst must analyze a reagent water blank to

demonstrate that interferences from the analytical system are under

control.

8.1.4 The laboratory must, on an ongoing basis, spike and analyze a

minimum of 10% of all samples to monitor and evaluate laboratory data

quality. This procedure is described in Section 8.3.

8.1.5 The laboratory must, on an ongoing basis, demonstrate through

the analyses of quality control check standards that the operation of

the measurement system is in control. This procedure is described in

Section 8.4. The frequency of the check standard analyses is equivalent

to 10% of all samples analyzed but may be reduced if spike recoveries

from samples (Section 8.3) meet all specified quality control criteria.

8.1.6 The laboratory must maintain performance records to document

the quality of data that is generated. This procedure is described in

Section 8.5.

8.2 To establish the ability to generate acceptable accuracy and

precision, the analyst must perform the following operations.

8.2.1 A quality control (QC) check sample concentrate is required

containing each parameter of interest at a concentration of 10 [micro]g/

mL in methanol. The QC check sample concentrate must be obtained from

the U.S.

[[Page 45]]

Environmental Protection Agency, Environmental Monitoring and Support

Laboratory in Cincinnati, Ohio, if available. If not available from that

source, the QC check sample concentrate must be obtained from another

external source. If not available from either source above, the QC check

sample concentrate must be prepared by the laboratory using stock

standards prepared independently from those used for calibration.

8.2.2 Prepare a QC check sample to contain 20 [micro]g/L of each

parameter by adding 200 [micro]L of QC check sample concentrate to 100

mL of reagent water.

8.2.3 Analyze four 5-mL aliquots of the well-mixed QC check sample

according to Section 10.

8.2.4 Calculate the average recovery (X) in [micro]g/L, and the

standard deviation of the recovery (s) in [micro]g/L, for each parameter

of interest using the four results.

8.2.5 For each parameter compare s and X with the corresponding

acceptance criteria for precision and accuracy, respectively, found in

Table 2. If s and X for all parameters of interest meet the acceptance

criteria, the system performance is acceptable and analysis of actual

samples can begin. If any individual s exceeds the precision limit or

any individual X falls outside the range for accuracy, then the system

performance is unacceptable for that parameter.

Note: The large number of parameters in Table 2 present a

substantial probability that one or more will fail at least one of the

acceptance criteria when all parameters are analyzed.

8.2.6 When one or more of the parameters tested fail at least one of

the acceptance criteria, the analyst must proceed according to Section

8.2.6.1 or 8.2.6.2.

8.2.6.1 Locate and correct the source of the problem and repeat the

test for all parameters of interest beginning with Section 8.2.3.

8.2.6.2 Beginning with Section 8.2.3, repeat the test only for those

parameters that failed to meet criteria. Repeated failure, however, will

confirm a general problem with the measurement system. If this occurs,

locate and correct the source of the problem and repeat the test for all

compounds of interest beginning with Section 8.2.3.

8.3 The laboratory must, on an ongoing basis, spike at least 10% of

the samples from each sample site being monitored to assess accuracy.

For laboratories analyzing one to ten samples per month, at least one

spiked sample per month is required.

8.3.1 The concentration of the spike in the sample should be

determined as follows:

8.3.1.1 If, as in compliance monitoring, the concentration of a

specific parameter in the sample is being checked against a regulatory

concentration limit, the spike should be at that limit or 1 to 5 times

higher than the background concentration determined in Section 8.3.2,

whichever concentration would be larger.

8.3.1.2 If the concentration of a specific parameter in the sample

is not being checked against a limit specific to that parameter, the

spike should be at 20 [micro]g/L or 1 to 5 times higher than the

background concentration determined in Section 8.3.2, whichever

concentration would be larger.

8.3.2 Analyze one 5-mL sample aliquot to determine the background

concentration (B) of each parameter. If necessary, prepare a new QC

check sample concentrate (Section 8.2.1) appropriate for the background

concentrations in the sample. Spike a second 5-mL sample aliquot with 10

[micro]L of the QC check sample concentrate and analyze it to determine

the concentration after spiking (A) of each parameter. Calculate each

percent recovery (P) as 100(A-B)%/T, where T is the known true value of

the spike.

8.3.3 Compare the percent recovery (P) for each parameter with the

corresponding QC acceptance criteria found in Table 2. These acceptance

criteria were calculated to include an allowance for error in

measurement of both the background and spike concentrations, assuming a

spike to background ratio of 5:1. This error will be accounted for to

the extent that the analyst's spike to background ratio approaches

5:1.⁷ If spiking was performed at a concentration lower than

20 [micro]g/L, the analyst must use either the QC acceptance criteria in

Table 2, or optional QC acceptance criteria calculated for the specific

spike concentration. To calculate optional acceptance criteria for the

recovery of a parameter: (1) Calculate accuracy (X') using the equation

in Table 3, substituting the spike concentration (T) for C; (2)

calculate overall precision (S') using the equation in Table 3,

substituting X' for X; (3) calculate the range for recovery at the spike

concentration as (100 X'/T)2.44(100 S'/

T)%.⁷

8.3.4 If any individual P falls outside the designated range for

recovery, that parameter has failed the acceptance criteria. A check

standard containing each parameter that failed the criteria must be

analyzed as described in Section 8.4.

8.4 If any parameter fails the acceptance criteria for recovery in

Section 8.3, a QC check standard containing each parameter that failed

must be prepared and analyzed.

Note: The frequency for the required analysis of a QC check standard

will depend upon the number of parameters being simultaneously tested,

the complexity of the sample matrix, and the performance of the

laboratory. If the entire list of parameters in Table 2 must be measured

in the sample in Section 8.3, the probability that the analysis of a QC

check standard will be required is high. In this case the QC check

standard should be routinely analyzed with the spiked sample.

8.4.1 Prepare the QC check standard by adding 10 [micro]L of QC

check sample concentrate

[[Page 46]]

(Section 8.2.1 or 8.3.2) to 5 mL of reagent water. The QC check standard

needs only to contain the parameters that failed criteria in the test in

Section 8.3.

8.4.2 Analyze the QC check standard to determine the concentration

measured (A) of each parameter. Calculate each percent recovery

(Ps) as 100 (A/T)%, where T is the true value of the standard

concentration.

8.4.3 Compare the percent recovery (Ps) for each

parameter with the corresponding QC acceptance criteria found in Table

2. Only parameters that failed the test in Section 8.3 need to be

compared with these criteria. If the recovery of any such parameter

falls outside the designated range, the laboratory performance for that

parameter is judged to be out of control, and the problem must be

immediately identified and corrected. The analytical result for that

parameter in the unspiked sample is suspect and may not be reported for

regulatory compliance purposes.

8.5 As part of the QC program for the laboratory, method accuracy

for wastewater samples must be assessed and records must be maintained.

After the analysis of five spiked wastewater samples as in Section 8.3,

calculate the average percent recovery (P) and the standard deviation of

the percent recovery (sp). Express the accuracy assessment as

a percent recovery interval from P-2sp to P+2sp.

If p=90% and sp=10%, for example, the accuracy interval is

expressed as 70-110%. Update the accuracy assessment for each parameter

on a regular basis (e.g. after each five to ten new accuracy

measurements).

8.6 It is recommended that the laboratory adopt additional quality

assurance practices for use with this method. The specific practices

that are most productive depend upon the needs of the laboratory and the

nature of the samples. Field duplicates may be analyzed to assess the

precision of the environmental measurements. When doubt exists over the

identification of a peak on the chromatogram, confirmatory techniques

such as gas chromatography with a dissimilar column, specific element

detector, or mass spectrometer must be used. Whenever possible, the

laboratory should analyze standard reference materials and participate

in relevant performance evaluation studies.

8.7 The analyst should monitor both the performance of the

analytical system and the effectiveness of the method in deal ing with

each sample matrix by spiking each sample, standard, and reagent water

blank with surrogate halocarbons. A combination of bromochloromethane,

2-bromo-1-chloropropane, and 1,4-dichlorobu tane is recommended to

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

stock standard solutions prepared as in Section 6.5, add a volume to

give 750 [micro]g of each surrogate to 45 mL of reagent water contained

in a 50-mL volumetric flask, mix and dilute to volume for a

concentration of 15 ng/[micro]L. Add 10 [micro]L of this surrogate

spiking solution directly into the 5-mL syringe with every sample and

reference standard analyzed. Prepare a fresh surrogate spiking solution

on a weekly basis. If the internal standard calibration procedure is

being used, the surrogate compounds may be added directly to the

internal standard spiking solution (Section 7.4.2).

9. Sample Collection, Preservation, and Handling

9.1 All samples must be iced or refrigerated from the time of

collection until analysis. If the sample contains free or combined

chlorine, add sodium thiosulfate preservative (10 mg/40 mL is sufficient

for up to 5 ppm Cl2) to the empty sample bottle just prior to

shipping to the sampling site. EPA Methods 330.4 and 330.5 may be used

for measurement of residual chlorine.⁸ Field test kits are

available for this purpose.

9.2 Grab samples must be collected in glass containers having a

total volume of at least 25 mL. Fill the sample bottle just to

overflowing in such a manner that no air bubbles pass through the sample

as the bottle is being filled. Seal the bottle so that no air bubbles

are entrapped in it. If preservative has been added, shake vigorously

for 1 min. Maintain the hermetic seal on the sample bottle until time of

analysis.

9.3 All samples must be analyzed within 14 days of

collection.³

10. Procedure

10.1 Table 1 summarizes the recommended operating conditions for the

gas chromatograph. Included in this table are estimated retention times

and MDL that can be achieved under these conditions. An example of the

separations achieved by Column 1 is shown in Figure 5. Other packed

columns, chromatographic conditions, or detectors may be used if the

requirements of Section 8.2 are met.

10.2 Calibrate the system daily as described in Section 7.

10.3 Adjust the purge gas (nitrogen or helium) flow rate to 40 mL/

min. Attach the trap inlet to the purging device, and set the purge and

trap system to purge (Figure 3). Open the syringe valve located on the

purging device sample introduction needle.

10.4 Allow the sample to come to ambient temperature prior to

introducing it to the syringe. Remove the plunger from a 5-mL syringe

and attach a closed syringe valve. Open the sample bottle (or standard)

and carefully pour the sample into the syringe barrel to just short of

overflowing. Replace the syringe plunger and compress the sample. Open

the syringe valve and vent any residual air while adjusting the sample

volume to 5.0 mL. Since this process of taking an aliquot destroys the

validity of the sample for future

[[Page 47]]

analysis, the analyst should fill a second syringe at this time to

protect against possible loss of data. Add 10.0 [micro]L of the

surrogate spiking solution (Section 8.7) and 10.0 [micro]L of the

internal standard spiking solution (Section 7.4.2), if applicable,

through the valve bore, then close the valve.

10.5 Attach the syringe-syringe valve assembly to the syringe valve

on the purging device. Open the syringe valves and inject the sample

into the purging chamber.

10.6 Close both valves and purge the sample for 11.00.1 min at ambient temperature.

10.7 After the 11-min purge time, attach the trap to the

chromatograph, adjust the purge and trap system to the desorb mode

(Figure 4), and begin to temperature program the gas chromatograph.

Introduce the trapped materials to the GC column by rapidly heating the

trap to 180 [deg]C while backflushing the trap with an inert gas between

20 and 60 mL/min for 4 min. If rapid heating of the trap cannot be

achieved, the GC column must be used as a secondary trap by cooling it

to 30 [deg]C (subambient temperature, if poor peak geometry or random

retention time problems persist) instead of the initial program

temperature of 45 [deg]C

10.8 While the trap is being desorbed into the gas chromatograph,

empty the purging chamber using the sample introduction syringe. Wash

the chamber with two 5-mL flushes of reagent water.

10.9 After desorbing the sample for 4 min, recondition the trap by

returning the purge and trap system to the purge mode. Wait 15 s then

close the syringe valve on the purging device to begin gas flow through

the trap. The trap temperature should be maintained at 180 [deg]C After

approximately 7 min, turn off the trap heater and open the syringe valve

to stop the gas flow through the trap. When the trap is cool, the next

sample can be analyzed.

10.10 Identify the parameters in the sample by comparing the

retention times of the peaks in the sample chromatogram with those of

the peaks in standard chromatograms. The width of the retention time

window used to make identifications should be based upon measurements of

actual retention time variations of standards over the course of a day.

Three times the standard deviation of a retention time for a compound

can be used to calculate a suggested window size; however, the

experience of the analyst should weigh heavily in the interpretation of

chromatograms.

10.11 If the response for a peak exceeds the working range of the

system, prepare a dilution of the sample with reagent water from the

aliquot in the second syringe and reanalyze.

11. Calculations

11.1 Determine the concentration of individual compounds in the

sample.

11.1.1 If the external standard calibration procedure is used,

calculate the concentration of the parameter being measured from the

peak response using the calibration curve or calibration factor

determined in Section 7.3.2.

11.1.2 If the internal standard calibration procedure is used,

calculate the concentration in the sample using the response factor (RF)

determined in Section 7.4.3 and Equation 2.

Equation 2

[GRAPHIC] [TIFF OMITTED] TC15NO91.095

where:

As=Response for the parameter to be measured.

Ais=Response for the internal standard.

Cis=Concentration of the internal standard.

11.2 Report results in [micro]g/L without correction for recovery

data. All QC data obtained should be reported with the sample results.

12. Method Performance

12.1 The method detection limit (MDL) is defined as the minimum

concentration of a substance that can be measured and re ported with 99%

confidence that the value is above zero. \1\ The MDL concentration

listed in Table 1 were obtained using reagent water.¹¹.

Similar results were achieved using representative wastewaters. The MDL

actu ally achieved in a given analysis will vary depending on instrument

sensitivity and matrix effects.

12.2 This method is recommended for use in the concentration range

from the MDL to 1000xMDL. Direct aqueous injection techniques should be

used to measure concentration levels above 1000xMDL.

12.3 This method was tested by 20 laboratories using reagent water,

drinking water, surface water, and three industrial wastewaters spiked

at six concentrations over the range 8.0 to 500 [micro]g/L.⁹

Single operator precision, overall precision, 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 3.

References

1. 40 CFR part 136, appendix B.

2. Bellar, T.A., and Lichtenberg, J.J. ``Determining Volatile

Organics at Microgram-per-Litre-Levels by Gas Chromatography,'' Journal

of the American Water Works Association, 66, 739 (1974).

3. Bellar, T.A., and Lichtenberg, J.J. ``Semi-Automated Headspace

Analysis of Drinking Waters and Industrial Waters for

[[Page 48]]

Purgeable Volatile Organic Compounds,'' Proceedings from Symposium on

Measurement of Organic Pollutants in Water and Wastewater, American

Society for Testing and Materials, STP 686, C.E. Van Hall, editor, 1978.

4. ``Carcinogens--Working With Carcinogens,'' Department of Health,

Education, and Welfare, Public Health Service, Center for Disease

Control, National Institute for Occupational Safety and Health,

Publication No. 77-206, August 1977.

5. ``OSHA Safety and Health Standards, General Industry'' (29 CFR

part 1910), Occupational Safety and Health Administration, OSHA 2206

(Revised, January 1976).

6. ``Safety in Academic Chemistry Laboratories,'' American Chemical

Society Publication, Committee on Chemical Safety, 3rd Edition, 1979.

7. Provost, L.P., and Elder, R.S. ``Interpretation of Percent

Recovery Data,'' American Laboratory, 15, 58-63 (1983). (The value 2.44

used in the equation in Section 8.3.3 is two times the value 1.22

derived in this report.)

8. ``Methods 330.4 (Titrimetric, DPD-FAS) and 330.5

(Spectrophotometric, DPD) for Chlorine, Total Residual,'' Methods for

Chemical Analysis of Water and Wastes, EPA 600/4-79-020, U.S.

Environmental Protection Agency, Environmental Monitoring and Support

Laboratory, Cincinnati, Ohio 45268, March 1979.

9. ``EPA Method Study 24, Method 601--Purgeable Halocarbons by the

Purge and Trap Method,'' EPA 600/4-84-064, National Technical

Information Service, PB84-212448, Springfield, Virginia 22161, July

1984.

10. ``Method Validation Data for EPA Method 601,'' Memorandum from

B. Potter, U.S. Environmental Protection Agency, Environmental

Monitoring and Support Laboratory, Cincinnati, Ohio 45268, November 10,

1983.

11. Bellar, T. A., Unpublished data, U.S. Environmental Protection

Agency, Environmental Monitoring and Support Laboratory, Cincinnati,

Ohio 45268, 1981.

Table 1--Chromatographic Conditions and Method Detection Limits

----------------------------------------------------------------------------------------------------------------

Retention time (min) Method detection

Parameter ------------------------------------ limit ([micro]g/

Column 1 Column 2 L)

----------------------------------------------------------------------------------------------------------------

Chloromethane............................................. 1.50 5.28 0.08

Bromomethane.............................................. 2.17 7.05 1.18

Dichlorodifluoromethane................................... 2.62 nd 1.81

Vinyl chloride............................................ 2.67 5.28 0.18

Chloroethane.............................................. 3.33 8.68 0.52

Methylene chloride........................................ 5.25 10.1 0.25

Trichlorofluoromethane.................................... 7.18 nd nd

1,1-Dichloroethene........................................ 7.93 7.72 0.13

1,1-Dichloroethane........................................ 9.30 12.6 0.07

trans-1,2-Dichloroethene.................................. 10.1 9.38 0.10

Chloroform................................................ 10.7 12.1 0.05

1,2-Dichloroethane........................................ 11.4 15.4 0.03

1,1,1-Trichloroethane..................................... 12.6 13.1 0.03

Carbon tetrachloride...................................... 13.0 14.4 0.12

Bromodichloromethane...................................... 13.7 14.6 0.10

1,2-Dichloropropane....................................... 14.9 16.6 0.04

cis-1,3-Dichloropropene................................... 15.2 16.6 0.34

Trichloroethene........................................... 15.8 13.1 0.12

Dibromochloromethane...................................... 16.5 16.6 0.09

1,1,2-Trichloroethane..................................... 16.5 18.1 0.02

trans-1,3-Dichloropropene................................. 16.5 18.0 0.20

2-Chloroethylvinyl ether.................................. 18.0 nd 0.13

Bromoform................................................. 19.2 19.2 0.20

1,1,2,2-Tetrachloroethane................................. 21.6 nd 0.03

Tetrachloroethene......................................... 21.7 15.0 0.03

Chlorobenzene............................................. 24.2 18.8 0.25

1,3-Dichlorobenzene....................................... 34.0 22.4 0.32

1,2-Dichlorobenzene....................................... 34.9 23.5 0.15

1,4-Dichlorobenzene....................................... 35.4 22.3 0.24

----------------------------------------------------------------------------------------------------------------

Column 1 conditions: Carbopack B (60/80 mesh) coated with 1% SP-1000 packed in an 8 ft x 0.1 in. ID stainless

steel or glass column with helium carrier gas at 40 mL/min flow rate. Column temperature held at 45 [deg]C for

3 min then programmed at 8 [deg]C/min to 220 [deg]C and held for 15 min.

Column 2 conditions: Porisil-C (100/120 mesh) coated with n-octane packed in a 6 ft x 0.1 in. ID stainless steel

or glass column with helium carrier gas at 40 mL/min flow rate. Column temperature held at 50 [deg]C for 3 min

then programmed at 6 [deg]C/min to 170 [deg]C and held for 4 min.

nd=not determined.

[[Page 49]]

Table 2--Calibration and QC Acceptance Criteria--Method 601 a

----------------------------------------------------------------------------------------------------------------

Limit for

Range for Q s Range for X Range P,

Parameter ([micro]g/L) ([micro]g/ ([micro]g/L) Ps (%)

----------------------------------------------------------------------------------------------------------------

Bromodichloromethane.................................... 15.2-24.8 4.3 10.7-32.0 42-172

Bromoform............................................... 14.7-25.3 4.7 5.0-29.3 13-159

Bromomethane............................................ 11.7-28.3 7.6 3.4-24.5 D-144

Carbon tetrachloride.................................... 13.7-26.3 5.6 11.8-25.3 43-143

Chlorobenzene........................................... 14.4-25.6 5.0 10.2-27.4 38-150

Chloroethane............................................ 15.4-24.6 4.4 11.3-25.2 46-137

2-Chloroethylvinyl ether................................ 12.0-28.0 8.3 4.5-35.5 14-186

Chloroform.............................................. 15.0-25.0 4.5 12.4-24.0 49-133

Chloromethane........................................... 11.9-28.1 7.4 D-34.9 D-193

Dibromochloromethane.................................... 13.1-26.9 6.3 7.9-35.1 24-191

1,2-Dichlorobenzene..................................... 14.0-26.0 5.5 1.7-38.9 D-208

1,3-Dichlorobenzene..................................... 9.9-30.1 9.1 6.2-32.6 7-187

1,4-Dichlorobenzene..................................... 13.9-26.1 5.5 11.5-25.5 42-143

1,1-Dichloroethane...................................... 16.8-23.2 3.2 11.2-24.6 47-132

1,2-Dichloroethane...................................... 14.3-25.7 5.2 13.0-26.5 51-147

1,1-Dichloroethene...................................... 12.6-27.4 6.6 10.2-27.3 28-167

trans-1,2-Dichloroethene................................ 12.8-27.2 6.4 11.4-27.1 38-155

1,2-Dichloropropane..................................... 14.8-25.2 5.2 10.1-29.9 44-156

cis-1,3-Dichloropropene................................. 12.8-27.2 7.3 6.2-33.8 22-178

trans-1,3-Dichloropropene............................... 12.8-27.2 7.3 6.2-33.8 22-178

Methylene chloride...................................... 15.5-24.5 4.0 7.0-27.6 25-162

1,1,2,2-Tetrachloroethane............................... 9.8-30.2 9.2 6.6-31.8 8-184

Tetrachloroethene....................................... 14.0-26.0 5.4 8.1-29.6 26-162

1,1,1-Trichloroethane................................... 14.2-25.8 4.9 10.8-24.8 41-138

1,1,2-Trichloroethane................................... 15.7-24.3 3.9 9.6-25.4 39-136

Trichloroethene......................................... 15.4-24.6 4.2 9.2-26.6 35-146

Trichlorofluoromethane.................................. 13.3-26.7 6.0 7.4-28.1 21-156

Vinyl chloride.......................................... 13.7-26.3 5.7 8.2-29.9 28-163

----------------------------------------------------------------------------------------------------------------

a Criteria were calculated assuming a QC check sample concentration of 20 [micro]g/L.

Q=Concentration measured in QC check sample, in [micro]g/L (Section 7.5.3).

s=Standard deviation of four recovery measurements, in [micro]g/L (Section 8.2.4).

X=Average recovery for four recovery measurements, in [micro]g/L (Section 8.2.4).

P, Ps=Percent recovery measured (Section 8.3.2, Section 8.4.2).

D=Detected; result must be greater than zero.

Note: These criteria are based directly upon the method performance data in Table 3. Where necessary, the limits

for recovery have been broadened to assure applicability of the limits to concentrations below those used to

develop Table 3.

Table 3--Method Accuracy and Precision as Functions of Concentration--Method 601

----------------------------------------------------------------------------------------------------------------

Single analyst

Parameter Accuracy, as recovery, precision, sr' Overall precision, S'

X' ([micro]g/L) ([micro]g/L) ([micro]g/L)

----------------------------------------------------------------------------------------------------------------

Bromodichloromethane................ 1.12C-1.02 0.11X+0.04 0.20X+1.00

Bromoform........................... 0.96C-2.05 0.12X+0.58 0.21X+2.41

Bromomethane........................ 0.76C-1.27 0.28X+0.27 0.36X+0.94

Carbon tetrachloride................ 0.98C-1.04 0.15X+0.38 0.20X+0.39

Chlorobenzene....................... 1.00C-1.23 0.15X-0.02 0.18X+1.21

Choroethane......................... 0.99C-1.53 0.14X-0.13 0.17X+0.63

2-Chloroethylvinyl ether a.......... 1.00C 0.20X 0.35X

Chloroform.......................... 0.93C-0.39 0.13X+0.15 0.19X-0.02

Chloromethane....................... 0.77C+0.18 0.28X-0.31 0.52X+1.31

Dibromochloromethane................ 0.94C+2.72 0.11X+1.10 0.24X+1.68

1,2-Dichlorobenzene................. 0.93C+1.70 0.20X+0.97 0.13X+6.13

1,3-Dichlorobenzene................. 0.95C+0.43 0.14X+2.33 0.26X+2.34

1,4-Dichlorobenzene................. 0.93C-0.09 0.15X+0.29 0.20X+0.41

1,1-Dichloroethane.................. 0.95C-1.08 0.09X+0.17 0.14X+0.94

1,2-Dichloroethane.................. 1.04C-1.06 0.11X+0.70 0.15X+0.94

1,1-Dichloroethene.................. 0.98C-0.87 0.21X-0.23 0.29X-0.40

trans-1,2-Dichloroethene............ 0.97C-0.16 0.11X+1.46 0.17X+1.46

1,2-Dichloropropane a............... 1.00C 0.13X 0.23X

cis-1,3-Dichloropropene a........... 1.00C 0.18X 0.32X

trans-1,3-Dichloropropene a......... 1.00C 0.18X 0.32X

Methylene chloride.................. 0.91C-0.93 0.11X+0.33 0.21X+1.43

1,1,2,2-Tetrachloroethene........... 0.95C+0.19 0.14X+2.41 0.23X+2.79

Tetrachloroethene................... 0.94C+0.06 0.14X+0.38 0.18X+2.21

1,1,1-Trichloroethane............... 0.90C-0.16 0.15X+0.04 0.20X+0.37

1,1,2-Trichloroethane............... 0.86C+0.30 0.13X-0.14 0.19X+0.67

Trichloroethene..................... 0.87C+0.48 0.13X-0.03 0.23X+0.30

Trichlorofluoromethane.............. 0.89C-0.07 0.15X+0.67 0.26X+0.91

Vinyl chloride...................... 0.97C-0.36 0.13X+0.65 0.27X+0.40

----------------------------------------------------------------------------------------------------------------

X'=Expected recovery for one or more measurements of a sample containing a concentration of C, in [micro]g/L.

[[Page 50]]

sn'=Expected single analyst standard deviation of measurements at an average concentration found of X, in

[micro]g/L.

S\1\=Expected interlaboratory standard deviation of measurements at an average concentration found of X, in

[micro]g/L.

C=True value for the concentration, in [micro]g/L.

X=Average recovery found for measurements of samples containing a concentration of C, in [micro]g/L.

a Estimates based upon the performance in a single laboratory.\10\

[GRAPHIC] [TIFF OMITTED] TC02JY92.000

[[Page 51]]

[GRAPHIC] [TIFF OMITTED] TC02JY92.001

[[Page 52]]

[GRAPHIC] [TIFF OMITTED] TC02JY92.002

[[Page 53]]

[GRAPHIC] [TIFF OMITTED] TC02JY92.003

[[Page 54]]

Method 602--Purgeable Aromatics

1. Scope and Application

1.1 This method covers the determination of various purgeable

aromatics. The following parameters may be determined by this method:

------------------------------------------------------------------------

STORET

Parameter No. CAS No.

------------------------------------------------------------------------

Benzene.......................................... 34030 71-43-2

Chlorobenzene.................................... 34301 108-90-7

1,2-Dichlorobenzene.............................. 34536 95-50-1

1,3-Dichlorobenzene.............................. 34566 541-73-1

1,4-Dichlorobenzene.............................. 34571 106-46-7

Ethylbenzene..................................... 34371 100-41-4

Toluene.......................................... 34010 108-88-3

------------------------------------------------------------------------

1.2 This is a purge and trap gas chromatographic (GC) method