VOLTAMMETRIC DETERMINATION OF NIFEDIPINE USING COMMERCIAL SCREEN-PRINTED CARBON ELECTRODES: PHARMACEUTICAL FORMULATIONS AND BIOLOGICAL FLUIDS

Currently, there is a need for strict control over all products consumed, especially pharmaceutical products. Chromatographic techniques are commonly used in routine analyses due to their robustness and sensitivity [1]. However, a well-known issue in the scientific community is the high cost of such equipment, including maintenance and solvents, as well as the need for specific training to operate them [2]. In this study, we developed a simple and fast analytical method for the determination of nifedipine (NIF) in pharmaceutical products and biological fluids. Cyclic voltammetry (CV), scanning electron microscopy, and electrochemical impedance were used to characterize the SPCE. NIF exhibited four electrochemical signals: two oxidation peaks at 0.10 V and 0.60 V, and two reduction peaks at −0.30 V and −0.75 V (vs Ag). After 120 hours of exposure to ambient light, the signals at 0.60 V and −0.75 V disappeared, suggesting that these reactions were no longer occurring, which may indicate degradation of the original compound. Simultaneously, the signals at 0.10 V and −0.30 V increased in intensity, possibly due to the formation of new products resulting from NIF degradation. The electrochemical detection was optimized in Britton-Robinson buffer (0.1 mol L⁻¹, pH 4.0) using differential pulse voltammetry (DPV). DPV curves exhibited linear responses (R² = 0.9938) to nifedipine in the concentration range of 1.0–16.0 µM, with detection limits of 0.56 µM. The device was successfully applied to tablets, yielding satisfactory recoveries of 93.8% (n = 3). The proposed method offers several advantages, such as simplicity, rapid analysis procedures, and adequate sensitivity, making it a promising alternative for the analysis of NIF using disposable SPCEs, which can be employed in routine analysis.