An Analytical Method for Lasalocid Residues in Livestock Products

Shu-Chu Su*, Pi-Chiou Chang and Shin-Shou Chou

National Laboratories of Foods and Drugs, Department of Health, Executive Yuan

ABSTRACT

　A reverse phase high performance liquid chromatographic (RP-HPLC) method for the determination of lasalocid in the muscle and liver of chicken and cattle was developed. Lasalocid was extracted from samples with acetonitrile. After filtration, the extract was purified by liquid-liquid partition, concentrated by rotary evaporation, purified with a silica Sep-Pak cartridge, and finally determined by fluorimetric HPLC. The separation was performed on a Cosmosil 5C18-AR-II column (5 μm, 4.6 x 150 mm) with methanol/0.02M KH2PO4 (84/16, v/v) as the mobile phase, and lasalocid was detected at Ex 310 nm and Em 420 nm. Recovery studies were performed at the 0.05, 0.1 and 0.2 ppm fortification levels in each of the four commodities. Average recoveries were in the range of 93.17~95.61, 91.53~93.59, 96.93~97.70 and 90.42~95.92% from chicken muscle and liver, and bovine muscle and liver, respectively. Coefficients of variation for average recoveries were less than 5%. The limit of detection was 0.005 ppm in these four commodities. When 20 samples purchased from various markets in Taipei were analyzed, no lasalocid was detected.

Key words: lasalocid, coccidiostat, livestock product, high performance liquid chromatography (HPLC)