Determination of chlorpyrifos in water by large-volume direct aqueous injection capillary gas chromatography

Abstract

A technique is described for the injection of large-volume aqueous samples in capillary gas chromatography for the direct determination of chlorpyrifos in well water. An uncoated inlet of suitable length coupled to a thin-film methyl phenyl silicone capillary column was employed for the determination of low parts-per 10 9 (ppb) levels of the pesticide in water. Samples were injected without prior clean-up steps by using a 10-port valve, and detection was performed by electron capture. The method yielded high accuracy, precision (4.8% with 95% confidence at 0.9 ppb), and suitable linearity range (0.9–18 ppb). The method presented circumvents the extraction, filtration and centrifugation steps commonly used in the determination of trace organic components in aqueous matrices.