ABSTRACT
An automated analytical method for simultaneous determination of vitamin A and E in livers, fortified infant formulae and eggs has been developed based on on-line solid phase extraction (SPE) coupled with a dual gradient high performance liquid chromatography system with column-switching. Firstly, food samples were centrifuged after saponified in mixture solution of anhydrous alcohol, potassium hydroxide and ascorbic acid at 80 ℃ for 30 min. Secondly, the saponified sample was loaded and washed on the first dimension extraction column using methanol-water (60∶40, V/V). Afterwards, the targeted analytes were trapped and enriched on the SPE column. Finally, the trapped analytes were transferred to the second dimension analysis column by valve-switching technique for the following separation and determination. Several key factors such as the type of SPE columns, elution buffer as well as pH of washing solution were optimized. The results showed that the calibration curves of vitamin A and E were linear in the range of 0 . 02-20 mg/L with correlation coefficient (R2) more than 0. 9998. In addition, the limits of detection (S/N=3) were found in the range of 3. 0-30. 0 μg/L. The spiked recoveries of the vitamin A and E from livers, eggs and fortified infant formulae ranged from 87 . 3% to 115 . 0% with the relative standard deviations ( RSDs ) of 1 . 8% -4 . 6%. The developed method is simple, sensitive and rapid to determine vitamins A and E in animal derived food.