ION-SELECTIVE ELECTRODES IN ORGANIC-ANALYSIS - PRIMARY AMINE SELECTIVE POLYMERIC MEMBRANE ELECTRODES BASED ON A CALIX[6]ARENE IONOPHORE

Primary alkylamine selective electrodes were designed based on the host-guest interaction between calixarene ionophore and alkylammonium ions. The poly(vinyl chloride) (PVC) membrane electrode contains 1-3% m/m of an ester derivative of calix[6]arene as the neutral carrier and dioctyl phthalate as the plasticizer. At pH 3.2, the electrode exhibits a Nernstian response in the range 1 x 10(-1)-3 x 10(-4) Mol 1-1 hexylamine with a slope of 57.5 +/- 0.8 mV per concentration decade. The electrode has a fast response time of less than 1 min and a constant Nernstian response after 1 month of continuous measurement. In contrast to the traditional PVC ion-exchange membrane electrode, the present electrode system was found to be highly selective to primary amines. Hence, the primary amine content of a mixture of amines can be determined using the electrode with good accuracy and precision.