高效液相色谱-串联质谱法检测牛奶中头孢洛宁残留

建立了牛奶中头孢洛宁残留检测的高效液相色谱-串联质谱方法。1 g牛奶经乙腈沉淀蛋白质后,上清液于37℃水浴下氮气吹干,用1 mL甲醇-0.1%甲酸水溶液(3∶7,v/v)复溶,正己烷除脂净化后检测。流动相为乙腈和0.1%甲酸水溶液,梯度洗脱,经C18色谱柱分离,采用多反应监测正离子模式对头孢洛宁进行定性定量分析。采用基质匹配法对牛奶中头孢洛宁的含量进行标准校正,在2~200μg/L范围内,头孢洛宁质量浓度与其对应峰面积的线性关系良好,相关系数0.999。牛奶中加标样品的检出限(按S/N≥3计)为0.5μg/kg,定量限(S/N≥10计)为2μg/kg。在定量限、1/2最高残留限量、最高残留限量、2倍最高残留限量添加水平下,牛奶中头孢洛宁的平均回收率为78.5%~86.2%,日内相对标准偏差为1.5%~6.2%,日间相对标准偏差为2.9%~5.6%。该方法可用于牛奶中头孢洛宁的残留检测。

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.