RESUMO
An efficient method for the analysis of cefotaxime and its metabolite desacetylcefotaxime residues in eggs was developed based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).The samples were homogenized and extracted with acetonitrile/water (9∶1, V/V) solution.The fat was removed by hexane, and the other impurities were removed with C18 sorbent.The separation of cefotaxime and desacetylcefotaxime was performed on an Agilent Eclipse Plus C18 column (100 mm × 2.1 mm, 3.5 μm) using a mobile phase of 0.2% formic acid(A)-acetonitrile(B) by gradient elution.The analytes were detected by MS/MS in positive electrospray ionization mode (ESI+) and multiple reaction monitoring (MRM), quantitated by matrix-matched extemal standard method.Results showed that the calibration curves had a good linearity in the range of 1.0-143 μg/L (cefotaxime) and 1.0-120 μg/L (desacetylcefotaxime), respectively, with correlation coefficient R.2>0.999.Limits of detection (LOD, S/N=3) for cefotaxime and desacetylcefotaxime were 0.07 and 0.14 μg/kg, and limits of quantitation (LOQ, S/N=10) for cefotaxime and desacetylcefotaxime were 0.23 and 0.99 μg/kg, respectively.At three spiked concentration levels, the recoveries of cefotaxime and desacetylcefotaxime ranged from 83.1% to 103.0% and 88.2% to 101.0%, respectively, both with RSDs (n=6) less than 6.2%.The results demonstrated that the method was simple, quick, sensitive and reliable, and suitable for determination of cefotaxime and desacetylcefotaxime residues in eggs.