Quantification of vitamins in energy and sport drinks and fruit nectars
Under the optimized conditions, all the samples available were subjected to MEKC analysis. Fig. 5 shows the electropherograms obtained for a fruit nectar with added vitamins (A), a sport drink (B) and an energy drink (C). A summary of the vitamin contents found for all the drinks analysed is presented in Table 2. The analysis of the energy drinks (ED) showed that the content of particular ingredients in these drinks was diversified. In general, the found levels of B vitamins were similar (or almost the same) as the values on the product labels. However, sample ED1 showed a content of vitamin C lower than that labelled. This value might be caused by losses in storage and temperature, which is particularly problematic for vitamin C (easy oxidation). In all examined ED, the declared levels of B12 vitamin (0.38e2.5 mg/100 mL) were below the LOQ, which made not possible its determination simultaneously with the other vitamins. Regarding to the sport drinks (SD), details about vitamin composition in product labels were not given, and only ascorbic acid was found as the main vitamin component. In fortified