PHOSPHORYL CONTAINING PODANDS AS CARRIERS IN PLASTICIZED MEMBRANE ELECTRODES SELECTIVE TO QUATERNARY AMMONIUM SURFACTANTS

Open chain polyethers with phosphoryl-containing terminal groups have been studied as carriers in plasticized membrane electrodes that are s elective towards cationic surfactants. Host-guest complexation has als o been studied by means of batch extraction and bulk membrane transpor t experiments. For the various guests, the bulk membrane (chloroform) transport rate decreases in the series tetraalkyl ammonium > alkyl pyr idinium > alkyl ammonium, while the series of solvent extraction effic iency is exactly opposite; an explanation for this behaviour is propos ed. The performance of electrode membranes follows the series for bulk membrane transport. Among the ISE membranes of various composition, o ne containing the longest (seven oxygen atoms) podand, o-nitrophenyl o ctyl ether (plasticizer), and sodium tetraphenyl berate (anionic addit ive) performs the best. The slope of the electrode function equals 58. 5 mV/decade, the detection limit for dodecyltrimethylammonium is 3.2 x 10(-6) M. ISE response time is 5-10 s, the working pH range is 2-11 a nd lifetime is at least 6 months. The electrode selectivity is signifi cantly better than that of conventional ion-association and crown ethe r based electrodes.