Abstract:

A method for the determination of 3,5,6-trichloro-2-pyridinol (3,5,6-TCP) in human urine, which is the main metabolite of chlorpyrifos, has been established employing ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The urine samples were prepared by liquid-liquid extraction with dichloromethane-ethyl acetate (20:80, v/v) solution followed by the separation with the gradient elution of acetonitrile-water on an ACQUITY UPLC BEH C18 column. The analyte was detected by tandem mass spectrometry under the negative ion mode with the electrospray ionization (ESI) source and the selective ion recording (SIR) mode. Under the optimized conditions, the calibration curve was linear in the range of 0.005-0.4 mg/L. The limit of detection was 0.41 μg/L. The average recovery was 97.9%. The intra-and inter-day precisions calculated with RSDs were all within 15% at each quality control (QC) level. The developed method is simple, sensitive, accurate and repeatable, which has been successfully applied to determine the exposure level of 3,5,6-TCP in the real samples of human urine. The results show that this method is supportive for the exposure assessment in human health risk analysis and monitoring the biological burden of chlorpyrifos.

Key words: 3,5,6-trichloro-2-pyridinol, chlorpyrifos, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), urine