DETERMINATION OF CHLORPYRIFOS IN WATER BY LARGE-VOLUME DIRECT AQUEOUS INJECTION CAPILLARY GAS-CHROMATOGRAPHY

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 109 (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. © 1990.