Determination of residual isometamidium in cattle tissues and milk by HPLC

摘要

A method for determining the amount of the antitrypanosomal agent isometamidium (IMD) in cattle muscle, liver, fat and milk using HPLC was developed. The drug was extracted from a sample with acetonitrile-0.25 m ammonium formate methanol solution, and purified by liquid-liquid partition with ethyl acetate and water, followed by extraction of the water layer in the presence of NaCl with acetonitrile. After evaporation of acetonitrile, the residue was taken up in 1 ml of 0.25 m ammonium formate methanol solution. The amount of drug was determined by HPLC with detection at 380 nm using an octyl column (TSK-GEL Octyl-80Ts, 4.6 mm i.d.X150 mm), and acetonitrile-0.03 m citric acid containing 0.005 m sodium 1-heptanesulfonate (3:7) as an eluent. Recoveries of the drug from cattle muscle, liver, fat and milk spiked with 0.1μg/g of IMD were 76.0, 75.3, 88.0 and 89.0, respectively. The detection limit was 0.01μg/g. The analysis of IMD by LC/MS was also investigated.