Surfactant ion selective membrane electrodes

Calix[8]arene ethers, carboxylic esters having various p-substituents and acid are synthesized and studied. In a bulk membrane transport of dodecylpyridinium the better carrier is the simplest host, calix[8]arene octamethyl ether. Inversely, it is the worst carrier for dodecyltrimethylammonium; the better here is carboxy ester with adamantyl p-substituents. Various calixarenes are successfully used in plasticized membrane ion-selective electrodes (ISE) for both above ammonium and pyridinium surfactants. Operational characteristics, potentiometric selectivity and optimal membrane compositions are reported. Typical limit of detection is at the level of nx 10(-6) - 1 x 10(-5) M, response time 5 - 10 s, and lifetime is at least 6 months. ISE's selectivity is significantly better than that of ion-association and crown-ether based electrodes.