Analysis of dialkyl phosphate metabolites in hair using gas chromatography-mass spectrometry: A biomarker of chronic exposure to organophosphate pesticides

Abstract

The aim of our study was to develop and validate an analytical approach for the quantitative determination of three dialkyl phosphate (DAP) metabolites, dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP) and diethyl phosphate (DEP), of organophosphate pesticides (OPs) in hair samples. The proposed methodology comprises a decontamination step, solid–liquid extraction, followed by liquid–liquid extraction, pentafluorobenzyl bromide derivatization, clean-up on Florisil/PSA column and analysis by gas chromatography–mass spectrometry (GC-MS). Extraction recovery, obtained from 50 mg hair samples spiked at two concentration levels, ranged from 56.1 to 107.9% and the within-day precision ranged from 13.5 to 17.5%. Limits of detection (LODs) ranged from 0.02 to 0.10 ng mg⁻¹. The results obtained from the analysis of hair samples of 30 agricultural workers show the suitability of the proposed method for monitoring people occupationally exposed to OPs. The most frequently detected compound was DEP followed by DMP. This is the first report on the detection of dialkyl phosphates in human hair which reflects the ability of hair testing to assess chronic exposure to OPs.

Keywords::

• Hair
• organophosphate pesticides
• dialkyl phosphates
• gas chromatography
• mass spectrometry

Acknowledgements

This work is co-funded by the Prefecture of Heraklion Crete, Greece, ELKE University of Crete grant No. 2197 and Municipality of Itanos, Crete, ELKE UC grant N. 2059. The authors would like to express their gratitude to the Prefecture of Heraklion and Municipality of Itanos.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.