Abstract:

A reverse phase HPLC method was developed for the determination of tilmicosin residue in goat milk. Samples were extracted using methanol, and cleaned-up using SPE on a C18 cartridge with a mixture of acetonitrile and water (90:10, V/V) as the eluent [the washing with a mixture of acetonitrile and water (20:80, V/V) was carried out prior to elution]. The analysis was performed on a Symmetry column with a mobile phase composed of 0.1 mol/L ammonium acetate (adjusted to pH 5.0 with formic acid), acetonitrile and methanol (60:30:10, V/V) using a UV detector set at 280nm. The limit of quantification was 0.020 μg/ml and the linear range was 0.01－25 μg/ml, and the spike recoveries at three levels of 0.02－5 μg/ml were in the range of 90.3%－98.1% with a coefficients of variation ranging 4.1%－8.9%. The method can meet the requirement for tilmicosin residue analysis.

Key words: goat milk, tilmicosin, HPLC, residue determination