[Toxicokinetics of Chlorfenapyr and Its Metabolites in Rats]

To establish a chromatography-tandem mass spectrometry method for detecting chlorfenapyr and its metabolite tralopyril in blood, and to investigate the toxicokinetics in rats.

Chlorfenapyr (8 mg/kg) was administered orally to rats, and blood samples were collected from rats' canthus vein at 5 min, 15 min, 30 min, 1 h, 3 h, 6 h, 12 h, 24 h and 48 h after administration. The blood samples were extracted using 100 μL of 5% formic acid solution and 400 μL of acetonitrile. Chlorfenapyr was qualitatively and quantitatively detected by triple quadrupole gas chromatography-tandem mass spectrometry (GC-MS/MS) and tralopyril was detected by triple quadrupole liquid chromatography-tandem mass spectrometry (LC-MS/MS). The DAS 3.0 software was used to fit the toxicokinetic equations and calculate the toxicokinetic parameters.

Chlorfenapyr was detectable from 5 min to 24 h with a peak time of 1 h. Tralopyril was detectable from 15 min to 48 h with a peak time of 3 h. The toxicokinetic process of chlorfenapyr in rat blood conformed to a first-order absorption one-compartment open model, with the toxicokinetic equation described as C=e^-0.265t-e^-0.175t. Tralopyril conformed to the first-order absorption three-compartment model, and the toxicokinetic equation was C=47 361.069e^-2.209t-35 404.962e^-1.486t+11 956.363e^-0.512t. In the equations, C stands for the concentration of the target substance in the blood, e is the natural constant (≈2.718 28), and t stands for time.

This study optimized the detection method for chlorfenapyr and its metabolite tralopyril in blood. The toxicokinetic equations and parameters of chlorfenapyr and tralopyril can provide a reference for the estimation of oral intake time of chlorfenapyr.