Pesticide Analytical Methods — General Description and Quality Control Considerations

Abstract

Environmental samples are analyzed for organochlorine pesticides/PCB's as part of the Environmental Protection Agency's (EPA) Superfund Contract Laboratory Program (CLP). A new protocol is required because laboratories have difficulty meeting the present data acceptability criteria and because the surrogate now used is more chemically labile than the analytes determined with the protocol. The new pesticide/PCB protocol specifies an ultrasonic extraction procedure for soil and either continuous liquid-liquid or separatory funnel extraction of water. It describes clean-up procedures using gel permeation chromatography, adsorbtion columns and mercury, copper or tetrabutylammonium sulfate for sulfur removal. The protocol requires a dual gas chromatography (GC) column quantitation of 17 single component pesticides and nine multicomponent pesticides/PCB's using electron capture detection (ECD). The quality assurance/quality control (QA/QC) requirements include 12-hour GC performance checks, instrument and method blank requirements, matrix spike/matrix spike duplicate analyses every 20 samples and periodic performance checks of clean-up techniques. Validation of the protocol is being accomplished according to EPA guidelines for determining ruggedness, precision, bias, detection limits, and sensitivity.