Potentiometric determination of mefenamic acid in pharmaceutical formulation by membrane sensor based on ion-pair with basic dye

The characteristics, performance and application ofmembrane sensors based on ion-pair Brilliant Green mefenamate are described. The sensor's response to the mefenamate ion has the sensitivity of (86.0±2.0) mV/pC over the range of 9×10-5-1×10-2 mol/L and the detection limit of 4.5×10-5 mol/L at pH 8.5-12. The sensor is easily assembled at a relatively low cost and has fast response time (5-10 s). The proposed sensor displayed good selectivity for mefenamate ion in the presence of different substances. It was used to determine mefenamic acid in pharmaceuticals.