Development and Validation of a Bioanalytical method for the Determination of Levamisole Residue in Backyard Poultry Egg

Development of a bioanalytical method is often tricky and labour intensive due to its nature or the criteria set by regulatory bodies. In the present study, a simple, reliable and sensitive analytical method was developed for the determination of levamisole residue in chicken eggs. Levamisole and ronidazole (internal standard, IS) were separated on a C18 reversed-phase HPLC column. Following liquid-liquid extraction, chromatographic separation was accomplished with a mobile phase consisting of acetonitrile: 0.05M KH2PO4 at ratio of 20: 80, and the drug was detected at 235nm using a UV detector at a flow rate of 1.0ml/min at the ambient temperature. Linearity was obtained over the range 0.3125–10.0μg/ml for levamisole hydrochloride with lower limit of quantitation of 0.3125μg/ml. For each level of quality control samples, inter-and intra-day precision (%CV) was within ±15%. Absolutes extraction recovery of drug from plasma was ≥;60%. The residue limit of levamisole gradually increased from day 1 to day 3 and then declined from day4 to day 7. The highest level of residue after oral administration of 80mg/kg levamisole to chickens was on day 3 (0.599μg/g). This level was lower than the recommended maximum residue limit (MRL), thus, no withholding period was required for egg consumption following the administration of the levamisole solution.