Pyrethroids, organic compounds similar to natural pyrethrums, constitute the majority of insecticides. Pyrethroids are widely used around the world owing to their excellent selective toxicity to certain insects. In addition, they are easily found in daily life, accounting for most household pesticides. Owing to the easy access to pyrethroid insecticides, pyrethroid-related accidents and suicides have occurred yearly. For the first time, nine pyrethroids commonly used in South Korea and their seven major metabolites were simultaneously analyzed and validated in human plasma using liquid chromatography triple quadrupole mass spectrometry. Plasmas spiked with these pyrethroids and their metabolites were prepared and deproteinized via the addition of acetonitrile. This deproteinized supernatant was filtered and directly injected to ascertain the liquid chromatography-tandem mass spectrometry. For a sensitive and reproducible analysis, all the pyrethroid and metabolite analysis conditions for the multiple reaction monitoring mode were optimized in advance and employed. The validation parameters of the method, including the specificity, linearity, limit of detection, limit of quantification, accuracy, precision, recovery, matrix effect, and stability were also evaluated. The R2 value of linearity was greater than 0.997 for all the analytes, the accuracy ranged from 81.8% to 112.3%, the precision from 0% to 10.1%, and the recovery from 90.9% to 112.4%, depending on the analyte. The stability was 97.0% to 107.0% in fresh plasma and 97.6% to 107.7% in corrupt plasma. The results were satisfactory for all the validation parameters. Furthermore, authentic pyrethroid-poisoned samples were analyzed using this validation method, to determine the suitability; deltamethrin and its metabolites, cis-DBCA and 3-PBA, were successfully analyzed.
