EPA-NERL: 502.2 (by PID): VOCs in Water by GC/PID/ELCD

Summary
Analytes
Revision
Data and Sites

Official Method Name

Volatile Organic Compounds in Water by Purge and Trap Capillary Column Gas Chromatography with Photoionization and Electrolytic Conductivity Detectors in Series

Current Revision

Revision 2.1, 1995

Media

WATER

Instrumentation

Gas Chromatography with Photoionization Detection

Method Subcategory

Organic

Method Source

EPA-NERL

Citation

Methods for the Determination of Organic Compounds in Drinking Water - Supplement III (EPA/600/R-95-131)

Brief Method Summary

Inert gas is bubbled through a water sample to purge highly volatile organic compounds with low water solubility. Purged sample compounds are trapped in a tube containing suitable sorbent materials. When purging is complete, the sorbent tube is heated and backflushed with helium to desorb the trapped compounds onto a capillary gas chromatography (GC) column. The concentrations of compounds from the trap are measured using a capillary column GC system equipped with a photoionization detector (PID) and an electrolytic conductivity detector (ELCD) placed in series.

Scope and Application

This method determines purgeable volatile organic compounds (including some disinfection by-products) in finished drinking water, raw source water, or drinking water in any treatment stage.

Applicable Concentration Range

Approximate range is 0.02 - 200 ug/L. Range is analyte and instrument dependent.

Interferences

(A) Contamination of samples with volatiles in the laboratory and impurities in the purge gas and sorbent trap: Use PTFE/Teflon or metal gas lines and plumbing (no out-gassing plastics), and analyze blanks to minimize risk of contamination.

(B) Contamination from sample carryover: Rinsing apparatus with water and purging equipment between analyses can minimize contamination.

(C) Contamination from methylene chloride (MeCl): When determining MeCl (a ubiquitous solvent) wear clothes that have not been exposed to MeCl fumes and use stainless steel or copper carrier gas and plumbing lines (MeCl permeates PTFE) to minimize contamination.

(D) Water collected in the trap: Captured water can be released randomly during analysis. Reconditioning the trap after each use to minimize interference.

Quality Control Requirements

Initial demonstration of laboratory capability followed by regular analyses of laboratory reagent blanks (LRBs), field reagent blanks (FRBs), and laboratory fortified blank (LFB). Initial demonstration of laboratory capability includes the analysis of four to seven replicates of an LFB containing each analyte of concern at a concentration in the range of 0.1-5 ug/L. A method detection limit (MDL) must be determined for each analyte.

Sample Handling

Dechlorinate samples using 3 mg of sodium thiosulfate or 25 mg of ascorbic acid per 40 mL of sample to the sample bottle prior to collection. Additional amounts of sodium thiosulfate or ascorbic acid should be added per each 5 mg/L of residual chlorine.

All samples should be collected in duplicate. Overfill all bottles, making sure to leave no bubbles or headspace. Adjust the pH of all samples to less than 2 at the time of collection, but after dechlorination with two drops of 1:1 HCl for each 40 mL of sample. When sampling for THM analysis only, acidification may be omitted if sodium thiosulfate is used to dechlorinate the sample. If sample foams vigorously after addition of HCl, discard the sample, collect a set of duplicate samples, but do not acidify them. Store samples at 4^oC until analysis.

Maximum Holding Time

14 days.

Relative Cost

$201 to $400

Sample Preparation Methods

This method has 37 analytes associated with it.

Analyte	Detection Level	Bias	Precision	Spiking Level
1,1-Dichloroethene(75-35-4) 1,1-Dichloroethene 1,1-Dichloroethylene Ethene, 1,1-dichloro- Ethylene, 1,1-dichloro-, inhibited Vinylidene chloride Vinylidenechloride Vinylidine chloride asym-Dichloroethylene	N/A	100% Rec (SL)	2.40 % RSD (SL)	10.00 ug/L
1,1-Dichloropropene(563-58-6) 1,1-Dichloropropene 1,1-Dichloropropylene 1-Propene, 1,1-dichloro-	0.020 ug/L	103% Rec (SL)	3.50 % RSD (SL)	10.00 ug/L
1,2,3-Trichlorobenzene(87-61-6) 1,2,3-Trichlorobenzene Benzene, 1,2,3-trichloro-	N/A	106% Rec (SL)	1.80 % RSD (SL)	10.00 ug/L
1,2,4-Trichlorobenzene(120-82-1) 1,2,4-Trichlorobenzene 1,2,5-Trichlorobenzene 1,3,4-Trichlorobenzene Benzene, 1,2,4-trichloro- TCB Trichlorobenzene, 1,2,4- unsym-Trichlorobenzene	0.020 ug/L	104% Rec (SL)	2.20 % RSD (SL)	10.00 ug/L
1,2,4-Trimethylbenzene(95-63-6) 1,2,4-TMB 1,2,4-Trimethylbenzene Benzene, 1,2,4-trimethyl Benzene, 1,2,4-trimethyl- Pseudocumene Pseudocumol asym-Trimethylbenzene psi-Cumene	0.050 ug/L	99% Rec (SL)	1.20 % RSD (SL)	10.00 ug/L
1,2-Dichlorobenzene(95-50-1) 1,2-Dichlorobenzene Benzene, 1,2-dichloro- Dilantin db Dowtherm e o-Dichlorobenzene ortho-Dichlorobenzene	0.050 ug/L	102% Rec (SL)	2.10 % RSD (SL)	10.00 ug/L
1,3-Dichlorobenzene(541-73-1) 1,3-Dichlorobenzene Benzene, 1,3-dichloro- Benzene, m-dichloro- m-Dichlorobenzene	0.020 ug/L	104% Rec (SL)	1.60 % RSD (SL)	10.00 ug/L
1,4-Dichlorobenzene(106-46-7) 1,4-Dichlorobenzene Benzene, 1,4-dichloro- Chlorinated benzenes, mono- and di- Di-chloricide PDB Paramoth p-Dichlorobenzene para-dichlorobenzene	0.010 ug/L	103% Rec (SL)	2.10 % RSD (SL)	10.00 ug/L
Benzene(71-43-2) Benzene Benzol Coal naptha Cyclohexatriene Phene Pyrobenzol	0.010 ug/L	99% Rec (SL)	1.20 % RSD (SL)	10.00 ug/L
Bromobenzene(108-86-1) Benzene, bromo- Bromobenzene Monobromobenzene Phenylbromide	0.010 ug/L	99% Rec (SL)	1.70 % RSD (SL)	10.00 ug/L
Chlorobenzene(108-90-7) Benzene chloride Benzene, chloro- Chlorobenzene MCB Monochlorobenzene Phenyl chloride	0.010 ug/L	100% Rec (SL)	1.00 % RSD (SL)	10.00 ug/L
Chlorotoluene(25168-05-2) Benzene, chloromethyl- Chloromethylbenzene Chlorotoluene Toluene, ar-chloro-	N/A	N/A	N/A	10.00 ug/L
Cumene(98-82-8) (1-Methylethyl)benzene 2-Phenylpropane Benzene, 1-methylethyl- Cumene Cumol Isopropylbenzene	0.050 ug/L	98% Rec (SL)	0.90 % RSD (SL)	10.00 ug/L
Ethylbenzene(100-41-4) Benzene, ethyl Ethyl benzene Ethylbenzene Ethylbenzol Phenylethane	0.010 ug/L	101% Rec (SL)	1.40 % RSD (SL)	10.00 ug/L
Hexachlorobutadiene(87-68-3) 1,3-Butadiene, 1,1,2,3,4,4-hexachloro- Butadiene,hexachloro-1,3- Hexachloro-1,3-butadiene Hexachlorobutadiene Perchlorobutadiene	0.060 ug/L	99% Rec (SL)	9.50 % RSD (SL)	10.00 ug/L
MTBE(1634-04-4) 2-Methoxy-2-methyl propane MTBE Methyl tert butyl ether Methyl tert-butyl ether Methyl tertiary butyl ether Methyl-t-butylether Propane, 2-methoxy-2-methyl- tert-Butyl methyl ether	N/A	N/A	N/A
Mesitylene(108-67-8) 1,3,5-TMB 1,3,5-Trimethylbenzene Benzene, 1,3,5-trimethyl- Mesitylene Trimethylbenzol sym-Trimenthylbenzene	0.010 ug/L	101% Rec (SL)	1.40 % RSD (SL)	10.00 ug/L
Naphthalene(91-20-3) Moth balls Naphthalene Naphthalin Naphthene Tar camphor White tar	0.060 ug/L	102% Rec (SL)	6.20 % RSD (SL)	10.00 ug/L
Organics, semivolatile(E-12884) Organics, semivolatile Semi-volatile organics Semivolatile organics	N/A	N/A	N/A
Styrene(100-42-5) Benzene, ethenyl- Cinnamene Cinnamol Phenylethene Phenylethylene Styrene Styrol Styrolene Vinylbenzene	0.010 ug/L	104% Rec (SL)	1.30 % RSD (SL)	10.00 ug/L
Tetrachloroethene(127-18-4) 1,1,2,2-Tetrachloroethene 1,1,2,2-Tetrachloroethylene Ethene, tetrachloro- Ethylenetetrachloride Perchloroethylene Perclene Tetrachloroethene Tetrachloroethylene	0.050 ug/L	101% Rec (SL)	1.80 % RSD (SL)	10.00 ug/L
Toluene(108-88-3) Benzene, methyl Methacide Methylbenzene Methylbenzol Phenylmethane Toluene Toluol	0.010 ug/L	99% Rec (SL)	0.80 % RSD (SL)	10.00 ug/L
Total xylenes(1330-20-7) Benzene, dimethyl- Dimethylbenzenes Total xylenes Xylene (mixed isomers) Xylene, (total) Xylenes Xylols	N/A	N/A	N/A
Trichloroethene(79-01-6) 1,1,2-Trichloroethene 1,1,2-Trichloroethylene Ethene, trichloro Ethinyl trichloride Ethylene trichloride Ethylene, trichloro- TCE Tri-clene Trichloroethene Trichloroethylene	0.020 ug/L	100% Rec (SL)	0.78 % RSD (SL)	10.00 ug/L
Vinyl chloride(75-01-4) Chloroethene Ethene, chloro Ethene, chloro- Monochloroethylene Vinyl chloride Vinyl chloride (monomer)	0.020 ug/L	109% Rec (SL)	5.00 % RSD (SL)	10.00 ug/L
Volatile organic compounds(E-12419) Organic compounds, volatile VOCs Volatile organic compounds	N/A	N/A	N/A
cis-1,2-Dichloroethene(156-59-2) 1,2-Dichloroethylene (cis) 1,2-cis-Dichloroethene 1,2-cis-Dichloroethylene Acetylenedichloride, cis- Ethene, 1,2-dichloro-, (Z)- cis-1,2-Dichloroethene cis-1,2-Dichloroethylene cis-Acetylene dichloride	0.020 ug/L	97	1.70	10.00 ug/L
m-Xylene(108-38-3) 1,3-Dimethylbenzene 3-Xylene Benzene, 1,3-dimethyl- m-Xylene m-Xylol	0.010 ug/L	100% Rec (SL)	1.40 % RSD (SL)	10.00 ug/L
n-Butylbenzene(104-51-8) 1-Phenylbutane Benzene, butyl- n-Butylbenzene	0.020 ug/L	100% Rec (SL)	4.40 % RSD (SL)	10.00 ug/L
n-Propylbenzene(103-65-1) 1-Phenylpropane Benzene, propyl- Isocumene n-Propylbenzene	0.010 ug/L	103% Rec (SL)	2.00 % RSD (SL)	10.00 ug/L
o-Chlorotoluene(95-49-8) 1-Chloro-4-methylbenzene 1-Methyl-2-chlorobenzene 2-Chlorotoluene Benzene, 1-chloro-2-methyl- o-Chlorotoluene o-Tolylchloride	0.030 ug/L	94% Rec (SL)	3.10 % RSD (SL)	10.00 ug/L
o-Xylene(95-47-6) 1,2-Dimethylbenzene 2-Xylene Benzene, 1,2-dimethyl- o-Xylene o-xylol	0.020 ug/L	99% Rec (SL)	0.80 % RSD (SL)	10.00 ug/L
p-Chlorotoluene(106-43-4) 4-Chloro-1-methylbenzene 4-Chlorotoluene Benzene, 1-chloro-4-methyl- p-Chlorotoluene p-Tolyl chloride	0.020 ug/L	101% Rec (SL)	1.00 % RSD (SL)	10.00 ug/L
p-Cymene(99-87-6) 1-Methyl-4-(1-methylethyl) benzene 4-Isopropyl-1-methylbenzene 4-Isopropyltoluene Benzene, 1-methyl-4-(1-methylethyl)- Cymol Dolcymene Methylisopropylbenzene Paracymene p-Cymene p-Isopropyltoluene p-Methyl-cumene	0.010 ug/L	98% Rec (SL)	2.40 % RSD (SL)	10.00 ug/L
p-Xylene(106-42-3) 1,4-Dimethylbenzene 4-Xylene Benzene, 1,4-dimethyl- p-Xylene p-Xylol	0.010 ug/L	99% Rec (SL)	0.90 % RSD (SL)	10.00 ug/L
tert-Butylbenzene(98-06-6) 2-Methyl-2-phenylpropane Benzene, (1,1-dimethylethyl)- Benzene, tert-butyl- Dimethylethyl)benzene,(1,1- Pseudobutylbenzene Trimethylphenylmethane tert-Butylbenzene	0.060 ug/L	98% Rec (SL)	2.30 % RSD (SL)	10.00 ug/L
trans-1,2-Dichloroethene(156-60-5) 1,2-trans-Dichloroethene 1,2-trans-Dichloroethylene Acetylenedichloride, trans- Ethene, 1,2-dichloro-, (E)- trans-1,2-Dichloroethene trans-1,2-Dichloroethylene trans-Acetylene dichloride	0.050 ug/L	93% Rec (SL)	4.00 % RSD (SL)	10.00 ug/L

Precision Descriptor Notes:	Data were generated in a single laboratory using 7 replicate analyses of reagent water fortified to 10 ug/L with each analyte. Recoveries were quantified using an internal standard method (fluorobenzene served as the internal standard to generate data, except for cis-1,2 Dichloroethene and 2-Chlorotoluene, which were determined on a second column with an external standard). NOTE: Total xylenes is a regulatory parameter for drinking water, representing the sum of xylenes. See performance data for distinct xylenes.
Detection Level Note:	MDLs were determined using the standard deviation of replicate analyses of an analyte-fortified reagent water sample multiplied by the t-value for (# of samples - 1) degrees of freedom at the 99% confidence level. Detailed instructions for how MDLs are determined are found at 40 CFR part 136, Appendix B. Note: MDLs for 2-Chlorotoluene and cis-1,2 Dichloroethene were determined on Column 2 using an external standard method. All other MDLs were determined on Column 1 using a fluorobenzene internal standard.

Precision Descriptor Notes:

Data were generated in a single laboratory using 7 replicate analyses of reagent water fortified to 10 ug/L with each analyte. Recoveries were quantified using an internal standard method (fluorobenzene served as the internal standard to generate data, except for cis-1,2 Dichloroethene and 2-Chlorotoluene, which were determined on a second column with an external standard). NOTE: Total xylenes is a regulatory parameter for drinking water, representing the sum of xylenes. See performance data for distinct xylenes.

Detection Level Note:

MDLs were determined using the standard deviation of replicate analyses of an analyte-fortified reagent water sample multiplied by the t-value for (# of samples - 1) degrees of freedom at the 99% confidence level. Detailed instructions for how MDLs are determined are found at 40 CFR part 136, Appendix B. Note: MDLs for 2-Chlorotoluene and cis-1,2 Dichloroethene were determined on Column 2 using an external standard method. All other MDLs were determined on Column 1 using a fluorobenzene internal standard.

Revision	PDF/Link
Revision 2.1, 1995

The Water Quality Portal contains sample results from sites that use this method.

Download WQP data

Select data:

Sites only
Sample results only

File format:

Comma-separated
Tab-separated
MS Excel 2007+

Sites where this method was used

Loading Sites ...

EPA-NERL: 502.2 (by PID): VOCs in Water by GC/PID/ELCD

WHO WE ARE

LEGAL