Quantitation of neonicotinoid metabolites in human urine using GC-MS

A rapid and sensitive analytical method using gas chromatography-mass spectrometry (GC-MS) was developed for the measurement of neonicotinoid (NEO) metabolites 6-chloronicotinic acid (6CN), 2-chloro-1,3-thiazole-5-carboxylic acid (2CTCA) and 3-furoic acid (3FA) from human urine. After acid hydrolysis, the metabolites were extracted using solid phase extraction (SPE) column (Bond Elute Plexa PCX) and eluted with methanol. N,O-bis (trimethylsilyl) trifluoroacetamide with 1% trimethylchlorosilane (BSTFA-TMCS, 99:1) was used for the derivatization of metabolites and analyzed by GC-MS with the electron ionization mode. The elution solvent, derivatization reagent and its conditions were mainly optimized for improved detection and quantitation of the metabolites based on signal-to-noise ratio, recoveries and reproducibility. Our present method offered a sufficiently low limit of detection (0.1μg/L for each metabolite) with satisfactory within-run and between-day accuracy and precision (variability less than 12.3%, R.S.D). This method is simple, sensitive and precise, and has been successfully applied to quantify low concentrations of urinary 6CN, 2CTCA and 3FA for the occupational NEO exposures survey.