Biomonitoring of a propetamphos metabolite in human urine using gas chromatography-mass spectrometry

Abstract

Propetamphos (PPT) is a public health organophosphate pesticide universally used to control insects including cockroaches, flies and ants. Methylethylphosphoramidothioate (MEPT) is the major urinary metabolite of PPT. The objective of this study was to develop an effective method for the screening of urinary MEPT using gas chromatography-mass spectrometry, and to assess the exposure levels of MEPT in human populations. Dibutyl phosphate was used as an internal standard, and analyses of MEPT derivatized with pentafluorobenzyl bromide were performed using an Agilent 5975 inert MSD system. The validated method was applied to spot urine samples collected from sprayers (n=15), non PPT-sprayers in the same working population (n=15) and control volunteers (n=80) living in the same area. The calibration curves were obtained with standard-spiked pooled urine. The limit of detection (LOD) was 10 µg/L. Average within-run and between-run precision were 18.4 and 14.2%, and accuracies were 110.6 and 87%, respectively. Urinary MEPT in the PPT sprayers, non-PPT sprayers, and control volunteers were ranged from <LOD–22.3, <LOD–21.9 and <LOD–13.8 µg/L, respectively. Results of the study suggest that study participants including occupational sprayers might expose to low levels of PPT. The present biomonitoring method could be useful for quantitative measurement of urinary MEPT in highly exposed human populations.