Simultaneous Determination of Caffeine and Aspartame in Diet Supplements and Non-Alcoholic Beverages Using Liquid-Chromatography Coupled to Corona CAD and UV-DAD Detectors

Abstract

A method for the simultaneous determination of caffeine and aspartame in various diet supplements and non-alcoholic beverages is presented. The analytes were analysed by high-performance liquid chromatography coupled to a charged aerosol detector (Corona CAD) and ultraviolet-diode array detector (UV-DAD) simultaneously connected in series. The method was validated using a Thermo Hypersil Gold-C18 column packed with 5 μm shell particles (150 × 4.6 mm) and acetonitrile–water (15/85% v/v) mobile phase at a flow rate of 1.00 mL/min. The elaborated method was validated for linearity, precision and accuracy. The rapid HPLC–CAD–UV-DAD technique is suitable for quantifying caffeine and aspartame in the range of 0.25–75 μg/mL in diet supplements and non-alcoholic beverages. The limit of detection for caffeine and aspartame was 62 and 43 ng/mL for Corona CAD and 31 and 30 ng/mL for UV-DAD detector, respectively. Each analyte calibration curve had a correlation coefficient of at least 0.999 and was linear in the defined range. The accuracies of CAD and UV-DAD detection were all acceptable, with the mean value of 100% for aspartame and 98.3% for caffeine. Precision values ranged from 0.09% to 1.12%. The work has demonstrated that charged aerosol detector can be successfully used in a rapid screening technique for biologically active substances in non-alcoholic beverages and diet supplements.