Simultaneous Determination of Pyrethroid, Organophosphate and Carbamate Metabolites in Human Urine by Gas Chromatography–Mass Spectrometry (GCMS)

Abstract

We have developed a rapid, sensitive, and reliable method for simultaneous determination of the urinary metabolites of common insecticides in a single analytical run using gas chromatography–mass spectrometry (GCMS). Thirteen metabolites, one originating from carbamate, six from organophosphates, and seven from pyrethroids, were selected for method validation. Samples at different concentrations (0.5–15 µg/L) were prepared by mixing working solutions containing the analytes with blank urine. After acid hydrolysis for 45 min at 90 °C, samples were processed with liquid–liquid extraction and derivatization by N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) before analysis on GCMS. The limits of detection for all thirteen analytes were below 0.1 µg/L. The recovery rates, evaluated at two concentrations (1, 10 µg/L), were found to be 90.48%, on average. The precision of multiple analyses at three different concentrations (0.5, 5, 15 µg/L) within one day or between 10 days was evaluated, and the resultant relative standard deviations were 8.1% or under. We also applied this method to analyze genuine urine samples collected from 30 human subjects, and successfully detected all the metabolites, with detection frequencies more than 50% for pyrethroid metabolites. In summary, this method is not only as good as others in performance, but is advantageous in terms of cost effectiveness and multiplicity of analytes.

Relationship between Organophosphate and Pyrethroid Insecticides in Blood and Their Metabolites in Urine: A Pilot Study

“…Figure 2. Metabolisms of (a) OPs and (b) PYRs and structures of metabolites measured in the study (adapted from [37]).…”

“…Each urine sample was dispensed into several 5 mL Teflon-capped brown glass bottles and stored at −20 • C prior to processing and analysis. Metabolites of OPs and PYRs were processed and analyzed following the method developed previously [37]. Since most of the metabolites underwent Phase II metabolism, de-conjugation had to be conducted via acid hydrolysis.…”

“…The LODs ranged from 0.025-0.1 µg/L, and LOQs ranged from 0.1-0.3 µg/L for the 11 metabolite analytes. Details of process and analysis were described previously [37].…”

“…The study aimed to evaluate the insecticide concentrations in the form of parent compounds in blood and of their metabolites in urine, and to find the association between these two types of biomonitoring data. Based on an assay method previously developed by our research team [37], we were able to analyze the human specimens accurately and precisely. The result presented herein expects to establish a bridge across the gap between the exposure results generated from blood and urine sampling, and to help understand the domain of human exposure to insecticides better.…”

“…The main urinary metabolites of common organophosphate (OP) and pyrethroid (PYR) insecticides (modified from[37]). …”