Voltammetric determination of mixtures of caffeine and chlorogenic acid in beverage samples using a boron-doped diamond electrode

Herein, a boron-doped diamond (BDD) electrode that is anodically pretreated was used for the simultaneous determination of caffeine (CAF) and chlorogenic acid (CGA) by cyclic and adsorptive stripping voltammetry. The dependence of peak current and potential on pH, scan rate, accumulation parameters and other experimental variables were studied. By using square-wave stripping mode after 60 s accumulation under open-circuit voltage, the BDD electrode was able to separate the oxidation peak potentials of CAF and CGA present in binary mixtures by about 0.4 V in Britton–Robinson buffer at pH 1.0. The limits of detection were 0.107 µg mL−1 (5.51×10−7 M) for CAF, and 0.448 µg mL−1 (1.26×10−6 M) for CGA. The practical applicability of this methodology was tested in commercially available beverage samples.