Dosaggio degli acidi L-ascorbico e L-deidroascorbico in derivati vegetali

A method for HPLC determination of L-ascorbic and L-dehydroascorbic acids was developed. The method involves a post-column reaction with dithiotreitol to convert L-dehydroascorbic acid into L-ascorbic acid. Samples of orange juices as well as of strained tomatoes and tomato concentrates were analysed. The some samples were also analysed by the HPLC method proposed by the European Normalization Commitee (CEN). Results show that the method developed is more reliable and efficient than that proposed by CEN, especially as regards L-dehydroascorbic acid. During the trials, it was observed that tomato products contain considerable amounts of L-dehydroascorbic acid, which are sometimes even higher than those of L-ascorbic acid.