Cyclic Voltammetric Investigation of Caffeine at Anthraquinone Modified Carbon Paste Electrode

Electrochemical methods have been widely used for the determination of electroactive compounds due to their simplicity, sensitivity, stability, and low cost. A carbon paste electrode was modified with anthraquinone. Cyclic voltammetry (CV) was employed to study the properties of the modified electrode toward the oxidation of caffeine (CAF). Compared to the unmodified electrode, the AQMCPE showed excellent catalytic activity for the oxidation of caffeine. AQMCPE was used to determine CAF in drug samples electrochemically. SWV was used to plot the calibration curve and there was a good linear relationship between anodic peak current and CAF concentration in the range<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn>2.0</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>6</mml:mn></mml:mrow></mml:msup><mml:mo>-</mml:mo><mml:mn>8.0</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mtext>–</mml:mtext><mml:mn>4</mml:mn></mml:mrow></mml:msup></mml:math> M, with the correlation coefficient of 0.998 and a detection limit of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mn fontstyle="italic">1.43</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn fontstyle="italic">10</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn fontstyle="italic">7</mml:mn></mml:mrow></mml:msup></mml:math> M. The application of the modified electrode for the determination of CAF in pharmaceutical formulation showed good recovery with reproducible results.