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 × 10^-1-3 × 10^-4 mol l^-1 hexylamine with a slope of 57.5 ± 0.8 mV per concentration decade. The electrode. 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.