Yasmine Mohammed Eidris2017-11-082017-11-082015-10http://hdl.handle.net/123456789/7606Abstract In the present study, six samples ofvitamin Ccontaining tablets (ascorbic acid) from several manufacturers with different expiry dates were collected from different pharmacies, These samples were subjected to evaluation of the concentration of ascorbic acid in the selected samples by different methods such as titrimetric and iodometric titrations as well as high performance liquid chromatography (HPLC). The concentrations of ascorbic acid in these samples were assessed and found to be 410, 506, 242 ppm in sample 1, 2 and 3, respectively,also the concentrations ofdehydroascorbic acid in sample 4, 5, and 6 were found to be 200 ,92and 204 ppm, respectively. The selected samples were exposed to different conditions of heat and light (100 and 200watt), then analyzed using the above methods.The samples were a significant decrease of the concentration of ascorbic acidwhich could be attributed to conversion of ascorbic acid todehydroascorbic acid.Chemistry