Rapid determination of residues of five kinds of veterinary drugs in livestock products by HPLC

A simple and rapid method has been developed for simultaneous determination of five veterinary drugs and a derivative (5-propylsulfonyl-1H-benzimidazole-2-amine, thiabendazole, 5-hydroxythiabendazole, panazon, pyrimethamine and trimetoprim) in meat, liver, kidney and milk. The drugs were extracted from a sample by homogenizing with acetonitrile and then the mixture was filtered. The extracted solution of meat was poured onto an alumina column. The extracted solution of liver, kidney or milk was partitioned between saturated ammonium sulfate solution (pH 7.0) and ethyl acetate-n-hexane (4 : 1). The organic solvent layer was poured onto an alumina column. The solution containing the drugs was evaporated to dryness under reduced pressure. The HPLC analysis was carried out on a CAPCELL PAK C18 UG120 column (4.6 mm i.d. × 150 mm) with a gradient system of 0.1% phosphate buffer (pH 7.0)-acetonitrile as the mobile phase. The drugs were measured with ultraviolet and fluorescence detectors. The recoveries of the drugs at the level of 0.1 μg/g were 62.3∼100.0%. The detection limits were in the range of 0.005∼0.05 μg/g. This method should be useful to determine the above veterinary drugs in livestock products.