Potentiometric sensor for the indomethacin determination

A potentiometric indomethacin-selective sensor based on Rhodamine B indomethacinate ion-pair (IP) as a membrane carrier is reported. Influences of the membrane composition, pH, and possible interfering ions were investigated on the response properties of the electrode. The sensor exhibits significantly enhanced response toward indomethacinate ions over the concentration range 1 × 10− 4 mol L− 1 to 5 × 10− 2 mol L− 1 with a lower detection limit (LDL) of 3 × 10− 5 mol L− 1 and a slope of − 60 mV decade− 1. Fast and stable response, good reproducibility, long-term stability, applicability over a pH range of 6–10 is demonstrated. The proposed electrode shows good discrimination of indomethacin from several inorganic and organic ions. The proposed sensor has been applied for the direct potentiometric determination of indomethacin in pharmaceutical preparations.