Determination method of clomeprop and clomeprop acid in livestock and seafood products by LC-MS/MS.

A method using liquid chromatography with tandem mass spectrometry has been developed for the determination of clomeprop and its metabolite clomeprop acid in livestock and seafood products. Clomeprop and clomeprop acid were extracted with acetone-n-hexane mixture under acidic conditions, and were defatted by liquid-liquid separation using acetonitrile and n-hexane, followed cleanup with SAX and PSA cartridges. The average recoveries from 10 kinds of food (bovine muscle, bovine fat, bovine liver, milk, yellowtail, salmon, eel, fresh water clam, egg and honey) spiked at the level of the MRLs or at uniform limits (0.01 ppm) were in the range of 81-97% for clomeprop and 93-101% for clomeprop acid. Repeatability was in the range of 2.1-14% for clomeprop and 1.3-4.0% for clomeprop acid. The quantitation limits were 0.002 mg/kg for clomeprop and 0.00154 mg/kg (0.002 mg/kg as clomeprop) for clomeprop acid.