Simultaneous Determination of 10 preservatives and Sweeteners in oral liquid preparation of traditional Chinese medicine by MEKC

OBJECTIVE To develope a micellar electrokinetic chromatography(MEKC) method for the simultaneous determination of ten possible additives in 6 oral liquid preparations of traditional Chinese medicine. METHODS The samples were extracted with 40% acetonitrile aqueous solution, followed by vortex mixing, high-speed centrifugation and finally analyzed by MEKC. The chromatographic separation was performed on an uncoated fused-silica capillary column(75 μm×68.5 cm, effective length 60 cm) with 50 mmol·L^-1 borax buffer(pH 8.4, containing 20 mmol·L^-1 SDS). The separation voltage was 20 kV, and the column temperature was maintained at 25℃. The detection wavelength was set at 200 nm. RESULTS The 10 analytes showed good linearity within their respective concentration ranges, with correlations coefficients(r) of 0.996 9-0.999 7. The limits of detection(LOD) and limits to quantitation(LOQ) of the method were in the ranges of 0.05-0.15 μg·mL^-1 and 0.16-0.50 μg·mL^-1, respectively. The average recoveries ranged from 84.3% to 100.6%, with RSDs of 1.1%-5.1%. The detection results showed that sodium benzoate and ethyl paraben were detected in 30 oral liquid preparations of traditional Chinese medicine, while others were not detected. The detection rate of sodium benzoate was 100%, and the content was 0.09%-0.3%. The detection rate of ethyl paraben was 33%, and the content was 0.03%-0.05%. CONCLUSION The method has the advangtages of simple sample pretreatment, good specificity, accuracy, and high efficiency, and can be used for the determination of 10 additives in oral liquid preparations of traditional Chinese medicine.