胶束扫集电动色谱法测定牙膏中3种尼泊金酯

Determination of Three Nipagin Esters in Toothpaste by Capillary Electrophoresis Using Sweeping Micellar Electrokinetic Chromatography

利用胶束扫集电动色谱技术,建立了测定牙膏中3种尼泊金酯的方法。电泳缓冲体系含80 mmol/L SDS,20 mmol/L Na H2PO4（p H=2.80）和4%甲醇（V/V）,分离电压-20 k V,进样量80 s×18.0 cm,检测波长240 nm。讨论了缓冲溶液p H、缓冲盐浓度、SDS浓度、分离电压、样品溶液中SDS浓度、样品溶液电导率、进样时间等因素的影响。方法的线性范围对尼泊金甲酯、尼泊金乙酯和尼泊金丙酯分别为0.800～400、0.800～400、0.800～200 mg/L,检出限均为0.20 mg/L,相关系数≥0.9996。方法具有样品处理简单,操作简便,灵敏度好,经济实用等优点,应用于牙膏样品测定,回收率在91.4%～110%之间,RSD≤1.3%。

Sweeping micellar electrokinetic chromatography （Sweep-MEKC） was used in determination of methyl p-hydroxybenzoate （MHB）, Ethyl 4-hydroxybenzoate （EHB） and Propyl p-hydroxybenzoate （PHB） in toothpaste. The buffer contained 80 mmol/L SDS, 20 mmol/L NaH2PO4 （pH=2.80） and 5 % CH3OH （V/V）. The separation voltage was -20 kV, injection time was 80 s by 18.0 cm, detected at 240 nm. Effect of pH, concentration of NaH2PO4, SDS, separation voltage, SDS in sample solution, conductivity of sample solution, and injection time were discussed. Under the optimum conditions, the linearities of regression equation were 0.800-400 mg/L fo MHB and EHB, and 0.800-200 mg/L for PHB, The LODs were 0.20 mg/L for the three samples, all of the correlation coefficients were better than 0.9996. The method was used in determination of real sample successfully with recoveries between 91.4 % and t 10 %, RSD≤ 1.3 %.