In a new paper by Lori Smith et al, published in the Journal of Food and Agricultural Chemistry (DOI: 10.1021/acs.jafc.7b02280), a wide and diverse range of anticoagulant rodenticides (ARs) were analyzed in rodent liver samples using UCT's dispersive SPE (d-SPE) tubes for sample clean-up. ARs are used to control rodent populations, acting as vitamin K antagonists by inhibiting vitamin K epoxide reductase. Consequently, formation of prothrombin and related blood-clotting factors (VII, IX and X) are blocked, causing massive hemorrhage and mortality. 

In the study, a sensitive and rugged quantitative method was developed, optimized and validated for eight ARs in liver using d-SPE tubes, each containing 175 mg magnesium sulfate, 100 mg, florisil, 50 mg alumina basic and 50 mg primary secondary amine (PSA). This method was employed to remove matrix interferences.  Target analytes were comprised of two chemical classes: hydroxycoumarins (warfarin, coumachlor, dicoumarol, bromadiolone, brodifacoum and difethialone) and indanediones (diphacinone and chlorophacinone). Liver extracts were cleaned up using d-SPE tubes and analyzed by reverse phase ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in negative ion mode, combined with multiple reaction monitoring (MRM). This methodology provided both simultaneous confirmation and quantitation of the analytes. 

The limits of detection ranged from 0.75ng/ g to 25 ng/g of sample. The limits of quantitation were established as 50 ng/g per analyte. Inter-assay method accuracy ranged from 92- 110% across the analytical range (50-2500 ng/g) using matrix-matched calibrators. The method showed good repeatability (RSDs 2-16%) and was successfully transferred to another laboratory utilizing a high resolution mass spectrometer providing high mass accuracy using a blind study. For more information on all of UCT's available d-SPE configurations, visit https://sampleprep.unitedchem.com/products/quechers/dispersive-clean-up/dspe.