毛细管区带电泳-间接紫外检测法测定婴儿配方奶粉中的胆碱

Determination of choline in infant formula by capillary zone electrophoresis with indirect ultraviolet detection

中文关键词:  毛细管电泳  间接紫外法  婴儿配方奶粉  胆碱  咪唑

英文关键词:capillary zone electrophoresis  indirect ultraviolet detection  infant formula  choline  imidazole

中文摘要:

      目的 建立毛细管区带电泳-间接紫外检测法测定婴儿配方奶粉中胆碱含量的新方法。方法 用 5 mmol/L乙酸提取婴儿配方奶粉样品中的胆碱, 涡旋混匀、9000 r/min离心, 上清液经0.45 μm醋酸纤维素滤膜过滤后进样。用未涂覆熔融石英毛细管75 μm ×70 cm (有效长度: 60 cm) 作为分离柱。以10 mmol/L磷酸二氢钠+20 mmol/L磷酸+7 mmol/L 4-甲基咪唑为分离缓冲体系。分离电压为28 kV, 进样压力及时间为0.5 psi、10 s, 检测波长为214 nm。结果 胆碱的校正峰面积与质量浓度在8.7~86.8 mg/L范围内间线性关系良好, 相关系数为0.9997、检出限为2.6 mg/L、定量限为8.7 mg/L, 方法的日内和日间精密度分别为1.9%和3.9%(n=7)。3个质量浓度添加水平的平均加标回收率分别为98.8%、95.2%及97.6%, 相应RSD分别为0.8%、0.9%及0.6%(n=5)。用本法分析了10件婴儿配方奶粉样品, 均获满意结果。结论 本方法简单、无需有机溶剂, 适用于婴儿配方奶粉中胆碱的常规检测。

英文摘要:

      Objective To establish a new method for the determination of choline in infant formula by capillary zone electrophoresis with indirect ultraviolet detection. Methods The choline in infant formula was extracted with 5 mmol/L acetic acid, the samples was mixed by vortex, centrifuged at 9000 r/min, and the supernatant was filtered by 0.45 μm cellulose acetate filtration membrane, then samples were injected. The separation was carried out on an uncoated fused-silica capillary 75 μm×70 cm (effective length: 60 cm). The separation buffer consists of 10 mmol/L sodium dihydrogen phosphate, 20 mmol/L phosphoric acid and 7 mmol/L 4-methylimidazole. The separation voltage was 28 kV and the injection time was 10 s at 0.5 psi. The detection wavelength was 214 nm. Results The corrected area and the mass concentrations had a good linear relationship in the ranges of 8.7-86.8 mg/L with a correlation coefficient of 0.9997. The limit of detection was 2.6 mg/L, and the limit of quantitation was 8.7 mg/L. The intra- and inter-day precision of the method were 1.9% and 3.9% (n=7), respectively. The average spiked recoveries of five replicates at three spiked levels were 98.8%, 95.2% and 97.6% with relative standard deviations of 0.8%, 0.9% and 0.6% (n=5), respectively. Ten infant formula samples were analyzed by this method and the results were satisfactory. Conclusion This method is simple without any consumption of organic solvents, which is suitable for the routine determination of choline in infant formula.