Novel and selective potentiometric membrane sensor for amiloride determination in pharmaceutical compounds and urine

A new PVC membrane sensor is described as a potentiometric sensor for amiloride. The sensor having amiloride–sodium tetraphenyl phthalate (ion-pair) as an electroactive material and dibutyl phthalate (DBP) as an anion excluder in PVC matrix in the percentage ratio of 4:66:30 (ion-pair: DBP:PVC) (w/w). The membrane sensor exhibits suitable response to amiloride in a concentration range of 1.0 × 10−2 to 1.0 × 10−6 mol L−1 with a limit of detection of 9.9 × 10−7 mol L−1. The slope of the system was −54.3 ± 1.0 mV decade−1 over pH range of 2.0–7.0. Selectivity coefficients for amiloride relative to a numbers of potential interfering substances were investigated. The sensor was highly selective for amiloride over a large number of similar compounds. The sensor showing a fast response time of 6 s and was used over a period of 2 months with a good reproducibility. The sensor was successfully applied to determination of amiloride in pharmaceutical samples with satisfactory results.