| Summary: | 碩士 === 靜宜大學 === 應用化學研究所 === 92 === Antioxidants and preservatives are important additives in cosmetics , and they can keep the quality of cosmetics. But these additives may induce contact dermatitis and carcinogenesis. The contents of the synthetic antioxidants and paraben could be detertmined simultaneously by high performance Liquid chromatography (HPLC) and micellar electrokinetic chromatography (MEKC). Furthermore, we estimated and compared the results of these two methods.
The optimum separation of HPLC with C18 column was performed by gradient of aqueous solution acetonitrile (pH 3). The adequate linear range from 0.4 ~ 120.0 ppm , the good correlation coefficient from 0.9940 to 0.9996, the acceptable detection limit of above 0.27 ppm, and shorter analytical time were obtained.
The characteristics of MEKC is the peak shape of neutral analyte could be improving by adding of SDS and MeOH. The optimal sample preparation was 20 mM SDS, 20 % MeOH in 10 mM sodium tetraborate buffer solution (pH9.2). The optimal separation was 40 mM of SDS, 15 % MeOH, and 1.2 M of urea in 10 mM sodium tetraborate buffer solution (pH9.2), 75 m I.D. ×75 cm (efficient length 50.0 cm), and 18kV of applied voltage. Under this condition, The linear range was from 0.5 to 60.0 ppm, the correlation coefficients were from 0.9966 to 0.9997.
The proposed analytical techniques of HPLC and MEKC were applied to analysis of commercial cream products with external standard method and standard addition method. The antioxidant of BHA and preservative of parabens were found as the intertsting additives. All of the contents of antioxidants and preservatives were within the limiting values in FDA. There were no significant difference indicated between the results from HPLC and from MEKC by paired t-statistical test at 96 % confidence level.
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