Fipronil desulfinyl

All samples were prepared according to Raju et al. (2016 (link)) and previously described in Contador-Kelsall et al. (2022 (link)). An Agilent 6490 Triple Quad Liquid Chromatography – mass spectrometry (LCMS) was used to analyse all samples. fipronil parent and metabolite compounds (fipronil, fipronil desulfinyl, fipronil sulfide, and fipronil sulfone) standards were purchased from Sigma-Aldrich. The R² for each calibration curve was above 0.996. All samples were run in negative mode and clearly defined, confirmed by their most abundant product ions at optimised collision energies. To ensure there was no contamination throughout, a positive control (0.01 μg/mL fipronil) and a negative control (acetonitrile) were run every five samples.

All samples were prepared according to Raju et al. (2016) (link). A single punch was taken from each dry blood spot card (DBS) and placed in an Eppendorf tube containing 100 μl of MilliQ water. The Eppendorf tube was centrifuged ensuring the DBS disc was completely immersed, followed by 5 min sonication. A 300-μl aliquot of acetonitrile was added to each sample followed by vortexing (2 min) and sonication (5 min). A supernatant (200 μl) was collected after centrifugation at 10000 rpm for 10 min. All preparation steps were performed at 4°C.
All samples were analysed using an Agilent 6490 Triple Quad Liquid chromatography–mass spectrometry. All standards for fipronil parent and metabolite compounds (fipronil, fipronil desulfinyl, fipronil sulfide and fipronil sulfone) were purchased from Sigma-Aldrich. Typical R² for each calibration curve was higher than 0.996. A positive control (0.01 μg/ml fipronil) and negative control (acetonitrile) were run every five samples to ensure no contamination. All compounds were run in negative mode, clearly defined and confirmed by their most abundant product ions at optimized collision energies.