New Insights on Naproxen Quantification Using Voltammetry and Graphite Electrodes: Development of an Optimized and Competitive Methodology
Figure 1. Naproxen’s chemical structure
Naproxen, acid ((S)-2-(6-methoxy-2-naftyl) propanoic acid) is a non-steroidal anti-inflammatory drug, frequently used to diminish pain, fever, inflammation and the stiffness provoked through osteoarthritis, rheumatoid arthritis, and other illnesses . Naproxen is considered an NSAID of the propionic acid group with a pKa of 4.2, it is liposoluble, practically insoluble in water at pH < 4, though when the pH > 6, the reverse is true .
The present work discuses new findings in the electrochemistry of naproxen over graphite electrodes. This new approach, along with a formal optimization of the variables related with differential pulse voltammetry, allows the proposal of a simple and competitive low-cost method to carry out naproxen’s voltammetric quantification. Naproxen’s indirect quantification through an adsorption anodic wave was performed at a graphite bar electrode using differential pulse voltammetry. An anodic current maximum was recorded at a potential of -0.3 V referred to a saturated Ag/AgCl reference electrode, in the presence of 0.1 mol dm-3 phosphates buffer at pH 7. A calibration plot was done, having a correlation coefficient of 0.990, with a sensibility of 4.19 ± 0.62 µA cm3 µg-1, with detection and quantification limits of 0.68 and 3.3 µg cm-3, respectively, and a quantification interval of 3.3 - 28.18 µg cm-3. The method proposed was adequate for naproxen quantification in pharmaceutical samples.
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