Comparative evaluation of UV-HPLC methods and reducing agents to determine vitamin C in fruits

Vitamin C is one of the most important antioxidant supplied by fruits and vegetables. Therefore a reliable and easy method is needed for its determination. In this work, two UV-HPLC methods for the determination of ascorbic acid were validated and compared in strawberries, tomatoes and apples. In addition, two different reducing agents [dl-1,4-dithiotreitol (DTT) or 2,3-dimercapto-1-propanol (BAL)] were tried for differentiate dehydroascorbic acid and determine vitamin C. Reliability resulted satisfactory for the UV-HPLC methods in each fruit. UV-HPLC methods resulted linear up to 5 mg/100 g and the least detection and quantification limits were <0.18 mg/100 g and <0.61 mg/100 g, respectively. Precision, as relative standard deviation, ranged from 0.6% to 3.9% and the recovery between 93.6% and 104.4%. Although, the UV-HPLC methods resulted useful for the routine analysis of AA and vitamin C in fruits, the best reliability was achieved when using a C18 column and DTT as reducing agent. Moreover, it may be the UV-HPLC method of choice because it is the easiest and cheapest to perform.