毛细管硅胶整体柱分离分析食品中有机酸

Separation and Analysis of Organic Acids in Food by Capillary Silica Monolithic Column

建立应用毛细管硅胶整体柱采用毛细管电色谱法分离分析食品中有机酸的方法。对影响毛细管电色谱分离效率的条件进行优化,色谱柱为本实验室制作的毛细管硅胶整体C18柱(100μm×40cm)、电压-6kV、进样时间10s、紫外检测波长200nm,流动相为150mmol/L磷酸二氢钠-60mmol/L硼砂缓冲溶液(浓度比为5:2)和0.5mmol/L十六烷基三甲基溴化铵,pH7.5、25℃。结果表明:草酸和富马酸的线性范围为10～1000μg/mL,丁二酸线性范围20～500μg/mL,酒石酸和柠檬酸的线性范围为15～1000μg/mL,线性相关系数r≥0.9986,平均回收率在89.8%～101.1%之间,相对标准偏差≤6.23%(n=5),检出限在3.0～7.5μg/mL之间。毛细管硅胶整体柱具有制作成本低廉,对加热、有机溶剂等稳定和重复使用次数多等优点,应用毛细管硅胶整体柱采用毛细管电色谱法可以方便、快速、高效地分离分析食品中有机酸。

A capillary electrochromatographic method for the separation and analysis of organic acids in food was proposed using a capillary silica monolithic column.Optimization of experimental parameters that influence separation efficiency was carried out.A capillary silica monolithic C18 column was prepared in our lab for the separation of organic acids using a mobile phase（pH 5.2） consisting of 150 mmol/L sodium dihydrogen phosphate-60 mmol/L borax buffer solution with a final concentration of 5：2 in the mixture and 0.5 mmol/L cetyl trimethyl ammonium bromide.Other experimental conditions were as follows： voltage-6 kV;injection time 10 s;column temperature 25 ℃;and detection wavelength 200 nm.Results showed that the linear range was 10–1000 μg/mL for oxalic acid and fumaric acid,20–500 μg/mL for succinic acid,15–1000 μg/mL for tartaric acid and citric acid.The average recovery rates for the organic acids were between 89.8% and 101.1%,with a relative standard deviation（RSD） less than or equal to 6.23%（n = 5）.The detection limits of the proposed methods were between 3.0 and 7.5 μg/mL.In conclusion,capillary silica monolithic column is inexpensive,stable to heat and organic solvents,and repeatedly usable.Capillary electrochromatography with capillary silica monolithic column allows simple,rapid and effective separation and analysis of organic acids in food.