EPA-NERL: 505:  Pesticides and PCBs in Water GC-ECD

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
Analysis of Organochlorine Pesticides and Commercial Polychlorinated Biphenyl (PCB) Products in Water by Microextraction and Gas Chromatography
Current Revision
Revision 2.1, 1995
Gas Chromatography with Electron Capture Detection
Method Subcategory
Method Source
  Methods for the Determination of Organic Compounds in Drinking Water - Supplement III (EPA/600/R-95-131)
Brief Method Summary
A 35-mL sample is extracted with 2-mL of hexane. The concentrations of pesticides and PCBs in the extract are measured using a gas chromatography (GC) system equipped with a linearized electron capture detector (ECD).
Scope and Application
This method determines organochlorine pesticides and polychlorinated biphenyls (PCBs) in finished drinking water, drinking water during intermediate stages of treatment, and the raw source water.
Applicable Concentration Range
Ranges differ for each analyte depending on matrix and instrumentation.

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

(B) Reagent contamination: Use high purity reagents.

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

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

(E) Variable solvents: Use the same solvent for each analysis.

(F) Endrin degradation: The splitless injector may cause endrin degradation. Endrin can break down by reacting with the active sites on the port sleeve.

(G) PCBs loss to glass surfaces: Rinse glass and minimize sample contact with glass to prevent adsorption loss of PCBs.

(H) Oxidation of target compounds: Oxidation of compounds (specifically easily-oxidized aldrin, hexachlorocyclopentadiene, and methoxychlor) can be prevented by adding sodium thiosulfate at collection.

(I) Phthalate interference: An unknown interference (possibly dibutyl phthalate) appears in heptachlors retention window.

Quality Control Requirements

Initial demonstration of laboratory capability, followed by analysis of laboratory reagent blanks (LRB), laboratory fortified blanks (LFB), laboratory fortified sample matrix (LFM), and quality control samples (QCS). A MDL for each analyte must also be determined.

Sample Handling

All samples should be collected in 40 mL bottles containing 3 mg of sodium thiosulfate crystals added just prior to shipping the bottles to the sampling site or 75 ug/L of freshly prepared sodium thiosulfate solution (0.04 g/mL) may be added to empty 40 mL bottles just prior to sample collection. Samples must be chilled to 4oC at the time of collection and maintained at that temperature until analysis.

Maximum Holding Time

14 days before extraction, except for heptachlor (7 days). Extracts up to 24 hours.

Relative Cost
$201 to $400
Sample Preparation Methods