Abstract: A high performance liquid chromatography tandem mass spectrometry method for detection of clonidine and cyproheptadine residue in pork liver was established. Samples were catalyzed by β-glucuronidase/ sulfatse and proteins were precipitated by addition of perchloric acid solution，and the residue was extracted with ethyl acetate\|isopropanol and purified by MCX SPE cartridge. Then clonidine and cyproheptadine was analyzed on the Venusil MP C18 column （100 mm x 2.1 mm，3 μm） with gradient elution program. The mobile phase was consisted of water added with 5% （V/V） acetonitrile and acetonitrile added with 01% （V/V） formic acid and 5% （V/V） water. The flow rate was 0.25 mL·min-1and column temperature was set at 30℃. Qualitative and quantitative analysis was conducted in multiple reaction monitoring （MRM） mode, external standard method for quantitative analysis. When the concentration of clonidine or cyproheptadine was 1.0 -100.0 ng·mL-1，there was a good linear realtionship(r≥0.9994）. At the additional amount of 0.2，2.0 and 10.0 μg·kg-1 of standard chemicals，the recovery rates were 83.5%-92.3% with an RSD(n=6） of 4.2%-9.3% and a quantity limit of 0.2 μg·kg-1（the signal to noise ratio >10）. The newly developed method appeared to be precise，sensitive，simple and accurate to operate for the determination of clonidine and cyproheptadine contents in pork liver.

Key words: high performance liquid chromatography tandem mass spectrometry （HPLC\|MS/MS）, clonidine, cyproheptadine, pork liver