Abstract
A new simple, selective, rapid and precise thin-film organic membrane based micro-sensor was developed for potentiometric determination of amiloride drug. The membrane based microchips was constructed using (amiloride: tetraphenyl borate) ion pair as sensing material, o-nitophenyloctyl ether as plasticizer, potassium tetrakis(4-chlorophenyl) borate as anions excluder and PVC as supporting matrix. The thin-film micro-sensor based on this composition provides linear Nernestian response with sensitivity of 60 +/- 1 mV/concentration decade covering relatively wide concentration range of 5x10(-6) 1x10(-2) mol L-1 of amiloride over pH range of 3-8. The suggested micro-sensor provides fast response time (<10 s) and good selectivity for amiloride over some tested cations. The microchip was successfully applied in direct potentiometric determination of amiloride in its pharmaceutical formulation. The average recovery was 96% with a mean standard deviation <4%.