A liquid chromatography tandem mass spectrometry method to assess 41 pesticides in human hair

Pesticides are chemicals widely applied in agriculture and proven environmental contaminants; their hazards include harmful effects on human health, therefore the evaluation of exposure is relevant to risk assessment. Hair is a non-invasive specimen that incorporates pollutants allowing an extended exposure window to be surveyed. Aim of this work was to develop and validate an assay for measuring 41 pesticide active principles in human hair. Under optimised conditions, analytes were extracted by soaking hair in acetonitrile, in the presence of internal standards, under stirring and heating condition. Chemical separation was achieved using liquid chromatography with silica-based bonded phase chromatographic column. Detection and quantification were performed, with both positive and negative electrospray ionization, by a hybrid triple quadrupole/linear ion trap mass spectrometer operating in the scheduled selected reaction monitoring mode. The validated assay showed a linear dynamic range up to 10000 ng/L or 400 pg/mg hair, inter- and intra-run precisions <7%, and accuracies within 10% of theoretical concentrations. Limits of quantification were 1 ng/L or 0.04 pg/mg hair for most of the investigated pesticides. Matrix effect experiments showed that the use of internal standards allowed for the control of biases. The method was applied to the determination of pesticides in hair samples form occupationally and non-occupationally exposed individuals. The results of this study indicate that the developed assay is useful to assess pesticides in human hair following different exposure scenarios.