Use of a solid phase extraction method for the analysis of pesticides in groundwater by gas chromatography with electron capture and flame photometric detectors
Organophosphorous, organochlorine and electron-capture sensitive pesticides were extracted from water in a single step using a C18 solid phase extraction cartridge, eluted with ethyl acetate and isooctane and determined by GC with electron-capture and flame photometric detection. Analytical aspects of the method were studied with a linear regression model, including the linearity of the responses, repeatability and detection limits, which ranged from 3 to 35 µg l–1. The method of concentration employed did not contribute to a noticeable loss of the chemicals, with recoveries of over 90%, except for fenthion. The present method is applied to the analysis of 27 pesticides in groundwater, most of which are recovered at >70% efficiency which complies with the EPA criteria.