Research on Separation and Determination of Carnitine Enantiomers in Health Foods Based on Ultra-performance Convergence Chromatography

KeyWord:ultra-performance convergence chromatography  carnitine  health foods  enantiomer  chiral separation

Abstract:

      Separation of two carnitine enantiomers£¬i.e. D-carnitine and L-carnitine by ultra-performance convergence chromatography£¨UPC2£© was attempted£¬and a residue analytical method for these carnitine enantiomers in health food samples was established£®The solid and liquid health food samples were ultrasonically extracted with ethyl alcohol as the solvent£®After derivatization of the extracting solution£¬a chiral chromatographic column£¬Acquity Trefoil CEL1£¨3.0 mm ¡Á 150 mm£¬2.5 ¦Ìm£© column was adopted for separation£®The detection wavelenths for photo-diode array detector£¨PAD£© was 244 nm£®The separation effect of the two carnitine enantiomers reached the best when supercritical carbon dioxide and ammonium hydroxide£­methanol£¨1¡Ã99£¬by volume£© were taken as the mobile phases at a flow rate of 1.0 mL/min by gradient elution£®Results showed that there were good linear relationships for the two carnitine enantiomers in the range of 0.50£­20.00 mg/L£¬with correlation coefficients£¨r2£© greater than 0.999£®The quantitative limits of the method£¨S/N = 10£© for D-carnitine and L-carnitine were both 25 mg/kg£®Recovery experiment was carried out within the range of 25£­250 mg/kg£¬and the recoveries at three spiked levels ranged from 86.0% to 110%£¬with the relative standard deviations£¨RSD£© of 4.3%£­7.0%£®The method was used to detect standard carnitine racemates purchased from the reagent company in order to investigate its effectiveness and practicability£®The results suggested that D-carnitine accounted for 51.2% and L-carnitine accounted for 48.8% in the standard carnitine racemates£®This method was also used to detect the contents of D-carnitine and L-carnitine in 10 health foods purchased from the market£®The experimental results indicated that D-carnitine wasn't detected in the 10 health food samples£¬but L-carnitine was detected in all of them£¬with the content reaching 96%£­102% of the label value£®With the characteristics of rapid analysis£¬good separation effect£¬good reproducibility and low consumption of organic solvent£¬this method is applicable for both the determination of L-carnitine content in health food samples and purity analysis£®It provides a scientific support for the development and use of chiral drugs as well as the formulation of relevant regulations.