Determination of Lasalocid Sodium in Chicken Tissues by High Performance Liquid Chromatography with Fluorometric Detection

A high performance liquid chromatographic method (HPLC) is described for determining lasalocid sodium residues in chicken tissues. Lasalocid was extracted from tissues by homogenizing them with acetonitrile. The supernatant was washed with n-hexane saturated with acetonitrile, then applied to a Sep-pak silica cartridge. After evaporation, the residue was dissolved in methanol and determined by HPLC. Lasalocid was separated on a UNISIL PACK 5C18 column (4.6mm×25cm) by using a methanol-20mM phosphate buffer, pH 3.0 (9:1) as a mobile phase. Lasalocid was detected with a spectrofluorometer (excitation and emission wavelengths set at 310nm and 420nm, respectively). Recoveries of lasalocid sodium added to chicken muscles and chicken livers were in the ranges of 89.4-92.3% and 85.3-89.0%, respectively. The detection limit is 0.005ppm, which is adequate for residual analysis.