Residue Analysis of Six Penicillins in Milk by LC-MS/MS

Objective To establish a method for the detection of 6 penicillins residues in milk.Method The extracts were separated and detected by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS).Mass spectral acquisition was done in the positive ion mode by multiple reaction monitoring (MRM).The sample was cleaned-up and concentrated by SPE in a HLB column. The chromatography was performed by reversed-phase HPLC in a C_ 18 column with MRM detection. The mobile phase was acetonitrile (0.1% formic acid )- water(0.1% formic acid).Results The correlation coefficient was 0.991 within the linear range 0.2～2.0 ng/ml. The average recovery was above 90%, with RSD4.87%(n6).Conclusion The method is sensifive,specific and easy for detecting penicillias residues in milk.