Determination of cefalonium residue in milk by high performance liquid chromatography-tandem mass spectrometry

An analytical method was developed for the determination of cefalonium in milk by high performance liquid chromatography-tandem mass spectrometry( HPLC-MS /MS). A total of 1 g milk was deproteinized by acetonitrile. The supernatant was transferred into a test tube to be blown dry with N2 at 37 ℃. Then the residue was dissolved with methanol-0. 1% formic acid in water( 3∶ 7,v /v). The sample was determined by HPLC-MS /MS after the purification. The chromatographic separation was achieved on a C18 column using 0. 1% formic acid in water and acetonitrile as mobile phases with gradient elution. Qualitative and quantitative analyses were achieved by HPLC-MS /MS under positive ionization and multiple reaction monitoring( MRM) mode. Matrix-matched calibration curve was used for the quantification. Good correlation coefficients were obtained( r 0. 999) in the mass concentration range of 2- 200 μg /L. The limit of detection( LOD,S /N≥3) was 0. 5 μg /kg in milk,and the limit of quantification( LOQ,S /N≥10) was 2 μg /kg. The mean recoveries at the four levels of LOQ,1 / 2MRL( maximum residue level),MRL,2MRL were between 78. 5% and 86. 2%,with the intra-day relative standard deviations( RSDs) of 1. 5% to 6. 2% and inter-day RSDs of 2. 9% to 5. 6%. In conclusion, the established method can be applied for the determination of cefalonium residue in milk.