Abstract

NOVEL PVC MEMBRANE SELECTIVE ELECTRODES FOR DETERMINATION OF SALICYLIC ACID IN PHARMACEUTICAL PREPARATIONS

Bhata R. Chaudhari*

Abstract

Newly developed coated wire electrodes have been used for the determination of salicylic acid in pure form, pharmaceutical preparations. The proposed sensor incorporated salicylic acid phosphotungstate ion pair complex as electrical material in PVC matrix membrane and dioctylsebacate as solvent mediator. The selective electrodes were fabricated based on the incorporation of salicylic acid with the ion exchangers, phosphomolybdic acid (CTPPMA), phosphotungstic acid (CTP-PTA) and a mixture of both acid (CTP-PMA/PTA). The potential responses of the electrodes were influenced by the pH of tested solution. The resulting electrode demonstrates near –Nernstain response over wide linear range (10-4_10-2M) salicylic acid with lower limit of detection of 3.7x10-5 M and slope of 57.46 ±0.1 mV/decade. The electrode has fast and stable response, good reproducibility, long term stability (4 Months) and applicability over a wide pH range (4.5-8). The sensor displayed a good selectivity for salicylic acid with respective the number of common foreign inorganic, organic species, excipients and the filler added to the pharmaceutical preparation. Fortunatelythese materials do not interfere with the salicylic acid. The sensor was successfully applied for the determination of salicylic acid. Under the condition of pH 5-10, the electrodes exhibit linear response over concentration range 1.0 × 10-7 - 1.0 × 10-2 mol/L with Nernstian slopes (56.29 ± 0.09, 54.60 ± 0.09 and 58.17 ± 0.28 mV/ decade at 25°C). The influence of possible interfering species such as common inorganic cations, amino acids and different pharmacological related compounds was studied. The electrodes were successfully applied in determination of the drug in tablets by direct and standard addition potentiometry.

Keywords: Salicylic acid, Ion-selective electrodes, Potentiometry determination, pharmaceutical formulations.