分离测定化妆品中维生素C、维生素C葡萄糖苷和曲酸的流动注射——毛细管电泳方法

Separation and determination of L-ascorbic acid,ascorbyl glucoside and kojic acid in commercial cosmetics by FI-CE

采用流动注射与毛细管电泳联用体系,建立了一种简单、快速、准确的测定化妆品中维生素C、维生素C葡萄糖苷及曲酸的新方法.实验所用的毛细管长度为30 cm(有效长度26.5 cm),检测波长为265 nm,运行缓冲溶液为20 mmol/L NaH_2PO_4(pH 7.10),运行电压10.0 kV.在此最佳条件下,3种物质可在5 min内实现基线分离,样品的进样频率可达到30 h^(-1).3种物质的线性方程相关系数均大于0.999 1.检测限(信噪比为3)分别为:维生素C 3.14μg/mL,维生素C葡萄糖苷2.67μg/mL,曲酸1.15μg/mL.方法的日内与日间的相对标准偏差均小于5.0%.该方法已用于市售化妆品中3种组分的含量测定,回收率在93.7%～104.1%之间,结果令人满意.

A simple, rapid and accurate method for the separation and determination of L-ascorbic acid, ascorbyl glucoside and kojic acid in commercial cosmetics was developed for the first time by a combination of flow injection（FI） and the capillary electrophoresis（CE） system. The analysis was carried out using an unmodified fused-silica capillary（75 μm I.D., 375 μm O.D., 30 cm total length, 26.5 cm effective length）, 10.0 kV applied voltage and direct ultraviolet detection at 265 nm. By a series of optimizations, a running buffer containing 20 mmol/L sodium dihydrogen phosphate（pH 7.10） was applied for the determination of the three analytes. The separation was achieved within 5 rain and the sampling throughput rate reached up to 30 h^-1 for real samples. The method resulted in excellent linearity, with correlation coefficients ≥0.9991 for the three analytes. The detection limits（defined as a signal-to-noise ratio of about 3） for L-ascorbic acid, ascorbyl glucoside and kojic acid were 3.14, 2.67, and 1.15 μg/mL, respectively. The repeatability（defined as relative standard deviation） was less than 5.0% for the intra-day and inter-day analysis. The levels of the analytes were successfully determined in cosmetic samples with recoveries ranging from 93.7% to 104.1%.