A total of 10 commercially available samples were purchased from a local supermarket: 4 energy drinks (ED1-4), 4 sport drinks (SD1-4) and 2 fruit nectars with added vitamins (FN1-2). Energy and sport drinks were filtered directly through 0.45 mm pore size nylon filter (Scharlau, Barcelona, Spain) and injected in the CE system. For carbonated samples, a previous sonication for 20 min to remove dissolved gases was performed. Fruit nectars with fortified vitamins were centrifuged at 10,000 rpm for 10 min, being the supernatant filtered and subsequently injected. Samples containing vitamin C were diluted 1:1 (v/v) with ice-cold metaphosphoric acid (up to a final concentration of 2%), filtered and injected.