气相色谱-质谱联用法快速检测乳制品中维生素E含量

目的建立正己烷涡旋辅助提取-气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)快速检测乳制品中α-生育酚和α-醋酸生育酚的分析方法。方法样品经甲醇沉淀蛋白后,采用正己烷涡旋提取,提取液以HP-5MS色谱柱分离,GC-MS选择离子监测模式测定。结果α-生育酚和α-醋酸生育酚在0.05~10 mg/L浓度范围内线性关系良好,相关系数均大于0.999;α-生育酚和α-醋酸生育酚检出限(S/N=3)分别为0.51 mg/kg和0.25 mg/kg,定量限(S/N=10)分别为1.70 mg/kg和0.83 mg/kg。质控样NIST SRM 1849a检测值与参考值偏差为-3.75%,日内相对标准偏差(RSD,n=5)为1.38%~2.25%,日间相对标准偏差为1.83%。结论该方法快速、准确、灵敏,适用于乳制品中维生素E含量的快速测定。

Rapid determination of vitamin E content in dairy products by gas chromatography-mass spectrometry

Objective To established a rapid method for the determination of alpha-tocopherol and alpha-tocopheryl acetate in dairy products using vortex-assisted extraction and gas chromatography - mass spectrometry (GC - MS). Methods Sample were extracted with n-hexane after products are mixed with methanol, which precipitates proteins and disrupts miscelles freeing lipids for extraction. Then the isooctane layer was separated by HP-5MS capillary chromatographic column and detected by selected ion monitoring (SIM) mode of GC-MS. Results Under the optimized condition, the calibration curves of target analytes were linear in the range of 0.05 - 10 mg/L with correlation coefficients higher than 0. 999. Limits of detection (LODs, S/N = 3) of alpha-tocopherol and alpha-tocopheryl acetate were 0.51 mg/kg and 0.25 mg/kg, respectively, and quantification (LOQs, S/N = 10) were 1.70 mg/kg and 0.83 mg/kg, respectively. he method was validated by NIST SRM 1849a, with the deviation of result and certified value at -3.75%. Intra-day repeatability of measurements (expressed as relative standard deviation) were between 1.38% and 2.25%, and inter-day repeatability was 1.83%. Conclusion The proposed method is fast, accurate and sensitive, which is suitable for detecting vitamin E in in dairy products.