Abstract
The electrochemical behavior of caffeine was investigated by using a simple, cheap, and highly selective pseudo carbon paste electrode. The electrode was characterized using scanning electron microscope (SEM). Cyclic voltammetry of caffeine showed only one oxidation peak at 1.46 V (vs. SCE) in phosphate buffer pH 7. Chemical calculations were performed using PM3 method to prove the electrochemical oxidation mechanism of caffeine studied by cyclic voltammetry. Square wave voltammetry was used for the direct electrochemical determination of caffeine. The effect of different experimental parameters was investigated on the peak height of caffeine. Caffeine showed a linear calibration curve ranged from 1 x 10(-6) to 1 x 10(-3) M, with 3.03 x 10(-7) standard deviation and a correlation coefficient of 0.999. A lower detection limit of 3.48 x 10(-7) M was obtained. The effect of ascorbic acid and paracetamol on the peak height of caffeine was studied. The proposed method has been successfully applied for the direct electrochemical determination of caffeine in different real samples such as tea, coffee, cola, and pharmaceutical formulations.