鼠李糖脂应用于微乳毛细管电动色谱快速测定化妆品中激素类物质

Rapid Determination of Corticosteroids in Cosmetics with Microemulsion Electrokinetic Chromatography with Rhamnolipid as Surfactant

采用生物表面活性剂鼠李糖脂建立了无需助表面活性剂的微乳体系,并应用于微乳毛细管电动色谱快速分析化妆品中皮质类激素泼尼松、泼尼松龙和氢化可的松。考察了pH值、鼠李糖脂浓度、离子强度、油相种类和浓度、分离温度、分离电压及进样电压和时间的影响,得出微乳体系最佳组成为0.1%(w/w)鼠李糖脂+0.8%(w/w)正庚烷+99.1%(w/w)硼砂缓冲液(80 mmol/L,pH 9.2)。分离温度20℃,分离电压20kV,电动进样10 kV×3 s,泼尼松、氢化可的松和泼尼松龙在9.4 min内可基线分离。重复进样7次,迁移时间和峰面积的RSD分别小于0.2%和5.0%。3种分析物线性范围均为5～100 mg/L;检出限分别为1.0,1.1和1.3 mg/L(S/N=3)。仅需简单萃取即可用于化妆品样品测定,回收率为81.6%～108%;RSD均小于4.8%。

Without co-surfactant,a rhamnolipids microemulsion was prepared and used in microemulsion electrokinetic chromatography to determine three corticosteroids,namely prednisone,hydrocortisone and prednisolone in cosmetics.The effects of pH of the running buffer,concentration of rhamnolipid,ionic strength,type and concentration of oil,capillary temperature,separation voltage and injection voltage and time were investigated,the optimum microemulsion consisted of 0.1%（w/w） rhamnolipids,0.8%（w/w） n-heptane and 99.1% borax buffer（80 mmol/L,pH 9.2）.Under the conditions of separation voltage of 20 kV,electrokinetic injection of 3 s/10 kV and capillary temperature of 20 ℃,the prednisone,hydrocortisone and prednisolone were baseline separated within 9.4 min.RSDs of migration time for three analytes were all less than 0.2% and RSDs of peak area were less than 5.0%（n=7）.Excellent linearity was obtained ranged from 5 to 100 mg/L,the detection limits based on ratio of signal to noise of 3 were 1.0,1.1 and 1.3 mg/L for three analytes respectively.The method has been applied to the determination of the three corticosteroids in actual cosmetic samples by simple extraction pretreatment,the recoveries of three analytes were between 81.6% and 108% and RSDs were less than 4.8%.This method is fast,simple,accurate and low cost,which could be used to monitor the quality of cosmetic products.