High Performance Liquid Chromatographic Determination of Ascorbic Acid in Tomato Products

Abstract

Ascorbic acid(ASA)in tomato products was determined by high performance liquid chromatography (HPLC) with a UV detector(254 nm)by stainless column(4.6×250 mm)packed with Fine SIL C₁₈-10. The mobile phase was 1% phosphoric acid. Tomato juice or vegetable juice was diluted with 4% metaphosphoric acid and passed through a micro filter (0.45μ). There μl of the filtrate was injected into a liquid chromatograph. The retention time of AsA was 4 minutes and 20 seconds. Analytical time of one sample was less than 14 minutes. The average recovery of AsA was 98.6%. AsA in tomato products was determined by HPLC and the indophenol method(AOAC method). With the average of the 8 different lots of tomato juice, the analytical value by indophenol method was 7.8% more than that by HPLC. It was caused by reductones except AsA. AsA in tomato juice that was oxidized by heating or oxygen was also determined by two methods. As a result, it was concluded that HPLC was very useful to grasp accurately and rapidly a decrease of AsA during processing or storage of tomato products.