Screening of pesticides via solid-phase extraction and gas chromatography

This work describes an analytical method for the screening of pesticide residues in water. The developed method identifies and quantitates a variety of pesticides in water samples such as organochlorine, organophosphate, chloronitrile, phthalimide, dicarboximide, and triazine. The analytical technique employed for the extraction and cleanup step involves solid-phase extraction with C-18 cartridges. The identification and determination of concentration is carried out with gas chromatography. Two columns of different polarity and two specific detectors are used. An electron capture detector is used for organochrolorine, and a thermoinic detector is used for organonitrogen and organophosphate. The good resolution achieved with the temperature program and the combination of columns is shown in the chromatograms obtained. The limits of detection, percent recovery, and their respective standard deviations are determined for each product. According to the results obtained, this method permits monitoring of the pesticides mentioned, many of which are moderately to highly toxic to aquatic organisms.