REVERSED-PHASE ION-PAIR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC QUANTITATION OF DIFETHIALONE RESIDUES IN WHOLE-BODY RODENTS WITH SOLID-PHASE EXTRACTION CLEANUP

A reversed-phase ion-pair high-performance liquid chromatographic meth od was developed for the determination of difethialone residues in lab oratory rats (Rattus norvegicus). Difethialone was extracted from rat tissue with chloroform/acetone/formic acid. The extracts were cleaned up by a solid-phase extraction (SPE) procedure using both, silica and aminopropyl SPE sorbents, concentrated, and analyzed by reversed-phase ion-pair high-performance liquid chromatography. Difethialone was qua ntitated via ultraviolet absorbance at 262 nm. A surrogate compound, b rodifacoum, was used to correct for method performance. The mean surro gate-corrected recoveries for whole ground rodent fortified at 0.2, 1. 0, and 20 mu g/g difethialone were 92.3 +/- 7.7, 84.8 +/- 6.6, and 90. 2 +/- 3.1%, respectively, The method limit of detection was 0.054 mu g /g.