Microwave extraction of incurred salinomycin from chicken tissues

A rapid, accurate, environmentally friendly and cost-effective microwave extraction technique was developed for the extraction of spiked and incurred salinomycin from chicken tissues (kidney, liver, muscle, ovarian yolk and fat). Extraction of salinomycin from various tissues was achieved by irradiating the sample in absolute ethanol and 2-propanol (15 + 2) for 9 sec. in a common household microwave oven. The extract was analysed without further cleanup by HPLC on a C18 column (5 microns) and detected at 592 nm via post-column reaction with 4-dimethylaminobenzaldehyde (DMABA) in a heated reactor coil at 86 degrees C. Recoveries of salinomycin from spiked tissues at 30 ng/g level ranged between 87 and 100%. The limit of quantitation was found to be 10 ng/g. The developed method was applied for the analysis of incurred tissues and ovarian yolk of laying chickens given sodium salinomycin in feed at different levels for 14 consecutive days followed by withdrawal periods. Residues were detected in all tissues and ovarian yolk at 0 withdrawal time but declined during the withdrawal period. Highest residue were found in fat and ovarian yolk.