Validation of a method to assess occupational exposure to tert-buthyl mercaptan by gas chromatography- mass spectrometry (GC-MS)

Background and Aims: Tert-butyl mercaptan is used as an important odorant of natural gas. Exposure to high concentrations of this substance lead to stimulating effects in human. Occupational exposure to mercaptan is measured by gas chromatography - flame photometer according to NIOSH ۲۵۴۲. The purpose of this study was to develop a method for sampling and analyzing tert-butyl mercaptan using GC_MS. Materials and Methods: In this study, tert-butyl mercaptan was analyzed using BP-۵ MS column and internal standard of ۴-methyl thiophenol. Calibration curve was developed and evaluated in the range of ۰.۴۵۱۰- ppm. Repeatability of method was presented by inter- day and intra-day assay based on the coefficient of variation (CV). Recovery of tert-butyl mercaptan was reported as the accuracy of method. All procedures of this study were approved by Shahid beheshti University of medical Science Institutional Review Board. Results: Retention time of tert-butyl mercaptan and ۴-methylthiophenol were determined as ۴.۰۵ and ۸.۰۱ min, respectively. Calibration curve was evaluated by the regression of ۰.۹۹. The mean recovery percent was ۹۸.۶۸ ± ۶.۶. Intra-day and inter-day coefficient of variance for standard concentrations was ranged between ۰.۴۶-۷.۲ percent. The limit of detection and limit of quantitation were presented ۰.۰۳۷ and ۱.۸۴ μg/sample, respectively. Conclusion: GC-MS method by validated parameters was suggested as a suitable alternative for NIOSH method.

Keywords:

Tert-buthyl Mercaptan , Natural Gas , Gas Chromatography-Mass Spectroscopy