DETERMINATION OF VALNEMULIN RESIDUES IN PORCINE TISSUES BY MOLECULARLY IMPRINTED SOLID-PHASE EXTRACTION COUPLING WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

A specific and simple high-performance liquid chromatography (HPLC) method for molecularly imprinted solid-phase extraction of the valnemulin from porcine tissues samples was investigated. Molecularly imprinted polymers (MIPs) with high selectivity to valnemulin were synthesized using pre-valnemulin as a dummy template. Valnemulin was extracted with acetonitrile from porcine tissues. Analysis was performed on a C18 column by detection in 210nm wavelength. The isocratic elution program was 65%acetonitrile in phosphate buffer solution (pH 2.5) with a flow rate of 1.0mL/min. The correlation coefficient (r) for calibration curve is higher than 0.999 within the experimental concentration range. Under the optimum conditions, the polymer sorbent can selectively extract and enrich valnemulin from porcine muscle, lung, and kidney tissues. Mean recoveries of valnemulin in porcine tissues spiked at 0.50, 5.0, and 50mg/kg ranged from 80.5%to 94.8%, with intra-day and inter-day relative standard deviations less than 10%. The limit of detection was approximately 0.1mg/kg and the limit of quantification was 0.25mg/kg. The MIP selectivity was evaluated by checking three drugs with similar and different structures to that of pre-valnemulin. The imprinted cartridge was better than the non-imprinted, C18 and MCX cartridges in terms of both recovery and selectivity.