Determination of water-soluble and fat-soluble vitamins - by capillary electrophoresis and evaluate with other methods

• Main Authors: Sun Pei Ching, 孫蓓菁
• Other Authors: 溫惠美
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/37342611683260880211

碩士 === 國立屏東科技大學 === 食品科學系 === 91 === The main purpose of this study was to develop the rapid method for determining the various vitamins in foods by capillary electrophoresis and expect to be accomplished by co-detected way for the multivitamins under the same analytical conditions. The optimal stock solvents for eight water-soluble vitamin standards were 0.001N HCl on Vit.B1、B3、B6 and PP , 5 ﹪ (H3PO3)n on Vit.C and iso.C, and 0.01N NaOH on Vit.B2 and folic acid, respectively. Mode of micellar electrokinetic capillary chromatography (MECC) was suitable to the eight vitamins separations with the optimal analytical conditions of 20 mM Na2B4O7 buffer solution (pH 9.2) which contained 50 mM sodium dodecyl sulfate (SDS), the detection wavelength of 300 nm (Vit.B group) and 254 nm (Vit.C group), applied voltage of 20 kV, and the operation temperature of 30 °C. Total separation time were about 15 minutes on either Vit.B group or Vit.C group. The optimal stock solvent for three fat-soluble vitamin standards (Vit.A acetate、E acetate and D3) were 99.5 ﹪ ethanol. The optimal separation conditions by mode of microemulsion electrokinetic chromatography (MEEKC) were as follows: buffer systems contained oil phase of 6 ﹪ (w/w) SDS with 0.8 ﹪ (w/w) n-octane, and water phase of 56.6 ﹪(w/w) 25 mM NaH2PO4 buffer solution (pH 2.5) which contained 30 ﹪ (w/w) ethanol and 6.6 ﹪ (w/w) 1-butanol.The detection wavelength were 340 nm (Vit.A acetate), 300 nm (Vit.E acetate) and 254 nm (Vit. D3), respectively. The applied voltage was 25 kV, operation temperature was 25 °C, and the total migration time were about 20 minutes. Comparing the suitability for determining the water-soluble and fat-soluble vitamin standards by CE method and other traditional methods, the results showed that each r2 of the linear regression was above 0.99, but with wider linear range for CE method, which were 0.1~100.8μg/mL on water-solubles, and 20.42~1154μg/mL on fat-solubles. Contrast to the traditional methods, they were generally narrower, which were 0.01~4.19μg/mL for Vit.B1 and B2 (fluorescence method), 0.535~34.24μg/mL for Vit.B3 and B6 (UV-visible method), and 1~5 ng/mL for folic acid (microbiology assay). Comparing the precision, the RSD of spectrophotometry method were ranged from 1.508~5.522 ﹪ on determining the vitamin standards of Vit.B1、B3 and B6, which were worse than that of CE method (2.214~3.163 ﹪).The RSD of the migration time for Vit.C analysis by HPLC were 0.672~3.564 ﹪, which was also worse than that of CE method (0.125~0.928﹪). But the opposite situation were shown on the peak area, its RSD by HPLC were 0.124~2.393 ﹪, which was better than that of CE method (5.678~6.896 ﹪). The RSD of the migration time for the analysis of Vit. A acetate and Vit. E acetate by HPLC were 0.171~1.121 ﹪and 0.082~0.217 ﹪, respectively. While those on the peak area were 3.112~4.555 ﹪and 4.139~1.071 ﹪, respectively. As to the CE method, the RSD of the migration time for Vit. A acetate and Vit. E acetate analysis, which were 0.423~1.465 ﹪and 0.364~1.391 ﹪, respectively, and of that were 4.132~5.367 ﹪and 4.964~5.348 ﹪for peak area. The results above indicated that the precision of HPLC method was better than that of CE method.As to the recovery, it ranged from 93.4~104.8 ﹪for each vitamin by CE method, and of that on traditional methods were ranged from 92.9~105 ﹪. As to the sensitivity test, the detection limit for each vitamin by CE were between 0.096~16.35μg/mL, and of that on traditional methods were between 0.004~1.018μg/mL. The detection limit for Vit.B3 and B6 by CE showed the better sensitivity, which were 0.131μg/mL and 0.096μg/mL, respectively, and of that by spectrophotometry were 1.018μg/mL and 0.268μg/mL, respectively. As to the other vitamins analysis (Vit.B1、B2、C、folic acid、A acetate and E acetate), CE showed the poorer sensitivity compared to the traditional methods. Applied the various methods on analyzing the thirteen samples, which composed of commercial vitamin tablets, drinks, and premixes, the results revealed that CE method for determining the Vit.B1、B2、 B3、B6、PP and folic acid, due to its rapid and easy-on-line advantages, makes it comparably more capable than that of conventional methods. But, it is only suitable on those high concentrations of vitamin-contained samples, e.g.vitamin tablets and premixes. As to the other vitamins (oxidative Vit.C, Vit. A acetate and Vit. E acetate) analysis or other low concentrations of vitamin-contained samples (e.g. drinks or yeast-feed), traditional methods will still be suggested , due to their better accuracy.