EPA-TSC/NERL: 508:  Chlorinated Pesticides in Water Using GCECD

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
 Determination of Chlorinated Pesticides in Water by Gas Chromatography with an Electron Capture Detector
Current Revision
Revision 3.1, 1995
Media
 WATER
Instrumentation
 Gas Chromatography with Electron Capture Detection
Method Subcategory
 Organic
Method Source
  EPA-TSC/NERL
Citation
  Methods for the Determination of Organic Compounds in Drinking Water - Supplement III (EPA/600/R-95-131)
Brief Method Summary
 A 1-L sample is extracted with methylene chloride by shaking in a separatory funnel or mechanical tumbling in a bottle. The methylene chloride extract is isolated, dried and concentrated after solvent substitution with methyl tert-butyl ether (MTBE). The concentrations of pesticides in the extract are measured using a capillary column gas chromatography (GC) system equipped with an electron capture detector (ECD).

NOTE: CAS Numbers in NEMI for cis- and trans- permethrin differ from those in the method. The CAS Numbers in NEMI are the correct ones.
Scope and Application
 This method determines certain chlorinated pesticides in groundwater and finished drinking water.
Applicable Concentration Range
 Ranges differ for each analyte.
Interferences

(A) Glassware contamination: Thoroughly clean glassware, including baking or solvent rinse.

(B) Reagent contamination: Use high purity reagents.

(C) Phthalate ester interference: Avoid the use of plastics and use pure reagents to avoid contamination by these ubiquitous compounds.

(D) Contamination from sample carryover: Rinsing apparatus with MTBE between analyses can minimize contamination.

(E) Extracted interferences: Interference from extracted non-target compounds, with retention times similar to target compounds, can be reduced by using confirmation analysis.

(F) Variable solvents: Use the same solvent for each analysis.
Quality Control Requirements
 Initial demonstration of laboratory capability, determination of surrogate compound recoveries in each sample and blank, monitoring internal standard peak area or height in each sample and blank (when internal standard calibration procedures are being employed), analysis of laboratory reagent blanks (LRBs), laboratory fortified samples, laboratory fortified blanks (LFBs), and QC samples. A MDL for each analyte must also be determined.
Sample Handling

Grab samples must be collected in glass containers following conventional sampling practices without prerinsing the bottle before collection. Dechlorinate with the addition of 80 mg of sodium thiosulfate per L of sample prior to sample collection. Store samples at 4oC until analysis.

NOTE: Samples analyzed for the following analytes must be extracted immediately after collection and preservation: chlorthalonil, alpha-HCH, delta-HCH, gamma-HCH, cis-permethrin, trans-permethrin, and trifluralin.
Maximum Holding Time
 7 days generally (see Sample Handling for exceptions).
Extracts within 14 days.
Relative Cost
 $201 to $400
Sample Preparation Methods
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