Simultaneous determination of nine anticoagulant rodenticides in soil and water by LC-ESI-MS.

A new and sensitive analytical method is presented to determine nine anticoagulant rodenticide (chlorophacinone, bromadiolone, pindone, diphacinone, warfarin, coumatetralyl, brodifacoum, floucomafen, and difenacoum) residues in water and soil samples by LC-ESI-MS. Rodenticides were extracted from soil using a methanol and ammonium formate 30 mM mixture, while ethyl acetate was employed in the water samples. A Gemini 5 μm C18 column was employed, and a mobile phase comprising a mixture of ammonium formate 30 mM and di-n-butylamine 30 mM in water (pH 3.5), ammonium formate 30 mM and di-n-butylamine 20 mM in water (pH 4.4), ammonium formate 30 mM in water (pH 6.5), and methanol in a gradient elution mode was selected. The method was fully validated and it was found to be selective and precise in terms of linearity and accuracy. Extraction recoveries ranged from 90 to 104% for the compounds studied, while the detection and quantification limits were between 0.09 and 2.2 μg/kg in soil or 0.08 and 1.7 μg/L in water. The method was applied to simultaneously measure these compounds in water and soil samples.