A Sensitive SPE-LC-MS/MS Method for Determination of Selected Veterinary Drugs and Other Organic Contaminants in Human Urine: Development, Validation, and Application Study

The complexity of human exposure to surrounding chemicals warrants developing analytical methods that are capable of the simultaneous quantitation of many diverse environmental pollutants and their biomarkers for the needs of human biomonitoring (HBM). Examples include pesticides used in veterinary medicine, such as fipronil (FIP), imidacloprid and pyrethroids, as well as other chemicals, like bisphenols and flame retardants. The goal of this paper was to develop and validate a liquid chromatography-tandem mass spectrometry method for the quantification of selected organic contaminants in human urine. The method was then applied to real samples and used to assess the potential of a new FIP biomarker, fipronil-hydroxy (FIP-OH), for HBM. As a sample preparation protocol, enzymatic deconjugation followed by solid phase extraction were used. The method was successfully developed and validated for 16 organic pollutants and/or their metabolites, with lower limits of quantitation ranging from 0.5 to 2000 pg/mL. FIP-OH could not be included in the method, possibly due to its chemical instability. In an application study among pet owners, the detection rate for FIP was 71% (median: 3.32 pg/mL); several other chemicals were also commonly detected. The results of validation and application experiments confirm that the method can be used in HBM studies to quantify organic pollutants in urine.