Analytical method for urinary metabolites of the fluorine-containing pyrethroids metofluthrin, profluthrin and transfluthrin by gas chromatography/mass spectrometry

An analytical method was developed for measurement of the major urinary metabolites in rats administered fluorine-containing pyrethroids (metofluthrin, profluthrin and transfluthrin) which are widely used recently as mosquito repellents or mothproof repellents. Eight metabolites, 2,3,5,6-tetrafluorobenzoic acid, 4-methyl-2,3,5,6-tetrafluorobenzoic acid, 2,2-dimethyl-3-(1-propenyl)-cyclopropanecarboxylic acid, 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (carboxylic metabolites), 2,3,5,6-tetrafluorobenzyl alcohol, 4-methyl-2,3,5,6-tetrafluorobenzyl alcohol, 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol and 4-hydroxymethyl-2,3,5,6-tetrafluorobenzyl alcohol (alcoholic metabolites), were extracted from enzymatic hydrolyzed urine using toluene and then concentrated. After transformation to their tert-butyldimethylsilyl derivatives for carboxylic metabolites or their trimethylsilyl derivatives for alcoholic metabolites, analysis was conducted by gas chromatography/mass spectrometry in the electron impact ionization mode. The calibration curves for each metabolite were linear over the concentration range of 0–20 μg/ml in urine, and the quantification limits were between 0.009 and 0.03 μg/ml. The relative errors and the relative standard deviations on replicate assays were less than 6% and 5%, respectively, for all concentrations studied. The measurements were accurate and precise. The collected urine samples could be stored for up to 1 month at −20 °C in a freezer. The proposed method was applied to the analysis of several urine samples collected from rats treated with these pyrethroids.

► We develop an analytical method of metabolites of fluorine-containing pyrethroids.
► They are used widely recently as mosquito repellents or moth-repellents in houses.
► The metabolites from hydrolyzed urine are analyzed by GC/MS(EI) after derivatization.
► They can be measured accurately and precisely.
► The collected urine samples can be stored for up to 1 month at −20 °C in a freezer.