A sensitive and efficient procedure for the high-throughput determination of nine urinary metabolites of pyrethroids by GC-MS/MS and its application in a sample of Japanese children.

Four pyrethroids (PYRs), metofluthrin, profluthrin, tefluthrin, and transfluthrin, which were newly developed and have relatively high vapor activity at ambient temperature, are now playing a key role in safely controlling insects in our daily lives. We developed a sensitive and high-throughput determination method for urinary metabolites derived from the newly developed PYR, e.g., 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH2-FB-Al), 2,3,5,6-tetrafluorobenzyl alcohol (FB-Al), and other PYR metabolites such as trans-chrysanthemumdicarboxylic acid (trans-CDCA) and 3-phenoxybenzoic acid (3PBA). After high temperature acid hydrolysis of 2 mL urine sample in 24-deep well plate, the PYR metabolites were extracted by semi-automated liquid-liquid extraction with tert-butyl methyl ether. N,O-Bis (trimethylsilyl) trifluoroacetamide containing 1% trimethylchlorosilane or 1,1,1,3,3,3-hexafluoroisopropanol were used for the derivatization of PYR metabolites, and the derivatized metabolites were analyzed separately by GC-MS/MS equipped with dual injector system (DB-5MS and mid- to high-polarity phase Rtx-65 columns). The derivatization and evaporation conditions were mainly optimized for improving sensitivity and reproducibility. The mean within-run day precisions were less than 18.4% (relative standard deviation, %RSD) with low detection limits ranging from 0.01 μg/L for HOCH2-FB-Al to 0.06 μg/L for trans-CDCA. This method was successfully applied to urine samples obtained from 50 3-year-old children with high detection frequencies (e.g., 82% for HOCH2-FB-Al and 84% for FB-Al). This method may be a pivotal tool for developing risk assessment from PYR exposure in the general population.