微乳毛细管电色谱电动进样-场放大堆积法检测化妆品中糖皮质激素

Determination of Glucocorticoids in Cosmetics by Microemulsion Electrokinetic Chromatography With Electric Injection and Field-amplified Sample Stacking

采用反向微乳毛细管电色谱电动进样联用场放大堆积，建立了在线富集检测化妆品中6种糖皮质激素分析方法。微乳毛细管电色谱缓冲体系为2．4％（w／w）十二烷基硫酸钠，6．6％（w／w）正丁醇，0．6％（w／w）正辛烷，20mmol／L磷酸盐缓冲液（pH2．2），分离电压-20kV，进样-20kVx54s，进水15kPax40S，检测波长240nm。讨论了样品基质、进样时间和电压、水柱长度对富集效果的影响。在优化条件下，6种激素的富集倍数分别为100～186倍，在0．05～15．0mg／L范围内呈线性关系，相关系数0．9986～0．9997。检出限为20—60μg/L（S／N=3），标准加入量为50μg／L时平均回收率85．9％-103．8％，相对标准偏差均小于5．8％。迁移时间和峰高的日内精密度分别为2．2％和7．9％，13间精密度分别为2．9％和9．0％。

Reverse migration microemulsion electrokinetic chromatography combined with electric injection and field-amplified sample stacking has been developed for the determination of 6 glucocorticoids in cosmetics. The microemulsion background buffer was composed of 2.4% （w/w） dodecyl sodium sulfate, 6. 6% （w/w） butanol, 0.6% （w/w） octane, 20 mmoL/L NaH2PO4 buffer （pH 2.2）. Separating voltage was -20 kV. The conditions of sample injection and water plug were -20 kV × 54 s and 15 kPa×40 s, respectively. Detection wavelength was at 240 nm. Several parameters were discussed including sample matrix, the length of sample injection and water plug. Under the optimum conditions, the enrichment factors of 100-186 were achieved. The calibration curves were linear at the concentration of 0. 05 to 15.0 mg/L with correlation coefficients of 0. 9986-0. 9997. The limit of detections were 20-60 μg/L （S/N = 3 ）. Mean recoveries at the spiked level of 50 μg/L ranged from 85.9% to 103.8%, with the relative standard deviation less than 5.8%. The RSDs of migration time and peak height were 2.2% and 7.9% （intraday）, 2.9% and 9.0% （interday）, respectively.