Development Of A Gas Chromatographic Method For Detection Of Levamisole Residues In Swine, Poultry And Goat Edible Tissues

A rapid and sensitive method using gas chromatography (GC) has been developed for the determination of the anthelmintic levamisole in edible tissues of swine, poultry and goats. The MRL (maximum residue limits) is fixed by Agricultural Department of PRC (People's Republic of China) at 100Hg/kg for liver, and 10Hg/kg for muscle, kidney and fat tissues of swine, poultry and goats. Levamisole was extracted from alkaline tissues with water-saturated ethyl acetate, back-extraction into hydrochloric acid. The acid layer was made alkaline to pH11~12 and extracted by chloroform. Sample of 1uL was automatically injected into the GC. All the chromatographic analyses were performed on a HP-6890 GC, equipped with nitrogen-phosphorus detection (GC-NPD). The capillary column was HP-5 (30m X 0.32mm). Nitrogen was used as a carried gas at a flow-rate of 2mL/min. The retention of levamisole is 9.37min. The LOD and LOQ of the standard solution were 0.025ug/mL and 0.05Mg/mL respectively. Calibration graphs were good linearity over the concentration ranges tested (0.05~3.2Hg/mL ,R=0.9996). LOD and LOQ of 5Mg/kg were obtained for the analysis of levamisole in muscle, kidney, fat and liver tissues. It corresponded in all cases to half the MRL except liver tissue. The mean extraction recoveries ranged from 69.7% to 90.7%. The intra-day and inter-day precisions and the results for accuracy fell with the ranges specified. The method has been successfully used for quantitative determination of levamisole in tissue samples.Residue depletion of levamisole was studied in hens. 5 groups of hens each were given levamisole at the dosage rate of 20 to 40mg per kilogram body weight via the feed. Residues of levamisole in liver, muscle, fat and kindey samples couldn't be detected in hens killed 5 days after the administration. Liver was designated the target tissue. The withdrawal is 3.8d based on MRL of 100Hg/kg for liver.This method is rapid, simple, sensitive and specific. It can be successfully used for residue depletion study of levamisole in edible tissues of swine, poultry and goats, according to the requirements defined by Agricultural Department of PRC.