Validation of an isocratic HPLC method based on the use of ABZ⁺ Plus phase for the simultaneous determination of methylxantines, chlorogenic acid, some hydroxy-benzoic and hydroxy-cinnamic acids. Application to cocoa, coffee, tea and cola-drinks

Validation of an isocratic HPLC method for determination of methylxantines, chlorogenic acid and some hydroxy-benzoic/cinnamic acids in nervine foods and beverages is described. The method proposed can be usefully employed by single-wavelength/UV/HPLC-equipped Quality Control Laboratories. The ABZ⁺ Plus phase permitted complete separation of 10 compounds in 20 min. k, asymmetry of peaks, number of theoretical plates at different pH (3.0, 3.5, 4.0) and temperature (30, 40 °C) were considered to determine best separation conditions. The method was then applied to some commercial samples of cocoa, coffee, tea and cola drinks, showing its real usefulness on quality control of these foods, particularly in monitoring roasting processes.