Simultaneous determination of methyl salicylate and thymol in various pharmaceutical formulations by differential-pulse voltammetry using a glassy carbon electrode

Abstract

A simple, rapid and accurate method for the simultaneous determination of methyl salicylate and thymol in various pharmaceutical formulations using differential-pulse voltammetry has been developed. Peak currents were measured with a glassy carbon electrode at +0.68 and +0.35 V versus a saturated calomel electrode for methyl salicylate and thymol, respectively. Water-methanol (1 + 1) was used as the solvent and sodium hydrogen carbonate as the supporting electrolyte. The linear calibration ranges for methyl salicylate and thymol were 0–2.46 and 0–2.00 µg ml^–1, respectively. The relative standard deviations at the 1.30 µg ml^–1 level of methyl salicylate and at the 1.20 µg ml^–1 level of thymol were 2.5 and 2.7%, respectively. Results are reported for seven pharmaceutical formulations.