ION-PAIR ISOLATION AND LIQUID-CHROMATOGRAPHIC DETERMINATION OF ALBENDAZOLE, OXFENDAZOLE, OXIBENDAZOLE, AND THIABENDAZOLE RESIDUES IN MILK

A liquid chromatographic [HPLC] method for the determination of Albend azole (ABZ), Oxfendazole (OFZ), Oxibendazole (OXBZ), and Thiabendazole (TBZ) residues in milk at levels below 3 ppb has been developed. Samp les were deproteinized with acetonitrile, defatted with hexane partiti on, and evaporated to constant volume. Following addition of acidified aqueous octane-l-sulfonate solution, the target benzimidazoles were s electively extracted as ion pairs into chloroform and analyzed on a re versed-phase C-18, 5 mu m, column. Overall recoveries were found to be 93.5 +/- 2.6% for OFZ, 90.0 +/- 1.3% for OXBZ, 85.7 +/- 3% for ABZ, a nd 74.0 +/- 2.6% for TBZ. Limited data on the depletion of OXBZ and AB Z in sheep milk were also generated.