Determination of Tilmicosin Residues in Swine Excreta by High Performance Liquid Chromatography

The concentrations of tilmicosin residues in swine excreta were determined by HPLC. Swine excreta were extracted with acetonitrile and 0.1mol·L-1 potassium dihydrogen phosphate buffer (pH 2.5). The extracts were applied to C18 solid-phase extraction (SPE) cartridge. The residue was eluted from SPE cartridge with methanol-acetonitrile-ammonium acetate (20:80:0.77, v:v:g), and the eluate was determined by HPLC at 290 nm. Recoveries of tilmicosin in urine fortified at 0.025μg·ml-1-2.0μg·m;-1 and in faeces fortified at 0.05μg·g-1-5.0μg·g-1 were in the range of 83.4%-95.7% and 58.8%-73.9%, respectively. Coefficients of variation were in the range of 6.6%-8.9% and 8.7%-12.4%, respectively. The limits of quantification (LOQ) were 0.025μg·ml-1 and 0.05μg·g-1 for tilmicosin in urine and faeces, respectively. The limits of detection (LOD) were 0.0125μg·ml-1 and 0.025μg·g-1 for tilmicosin in urine and faeces, respectively. The method complied with the requirement for tilmicosin correlative study.