Voltammetric determination of analgesics using a montmorillonite modified electrode

Three analgesics were studied voltammetrically using a sodium montmorillonite (NaMM) modified glassy carbon electrode. The voltammograms of analgesics were studied in pHs 1.0–13.0. Influence of pH, sweep rate and pharmaceutical formulations concentration were studied. One well-defined oxidation peak was observed for acetaminophen (AAP) and acetylsalicylic acid (ASA), three oxidation peaks for dipyrone (DP). The oxidation peak potential shifted towards negatively with change in pH. The oxidation was irreversible and diffusion-controlled for all pharmaceutical samples of acetaminophen, dipyrone, and acetylsalicylic acid. A systematic study of the experimental parameters that affect the square wave stripping voltammetric response was carried out and optimized conditions were arrived at. Under optimum conditions, stripping voltammetric procedure was developed for the determination of analgesics in pharmaceutical and urine at pH 1.0. A calibration plot was derived and the lower limit of determination was noticed as 0.02 μg mL− 1 for acetylsalicylic acid, 0.02 μg mL− 1 for acetaminophen and 0.04 μg mL− 1 for dipyrone. The percentage of rsd was also found.