A new dodecylsulfate-selective supported liquid membrane electrode based on its N-cetylpyridinium ion-pair

摘要

A supported liquid and a poly(vinyl chloride) (PVC)-based membrane selective for dodecylsulfate (DS-) ion are described. The active element is a membrane containing a dissolved ion association complex of DS- with cetylpyridinium (CP') cation. The supported liquid membrane electrode (acetophenone as solvent) showed a Nemstian response towards the DS- anion over the concentration range of sodium dodecylsulfate (SDS) from 8.3 x 10(-3) to 1.0 x 10(-6) mol dm(-3) at 25 degreesC. The proposed electrode also showed a super-Nernstian potential response (108 +/- 2 mV decade(-1)) at low concentrations (1.0 x 10(-9) to 1.0 x 10(-6) mol dm(-3)). Moreover, this electrode showed good selectivity and precision (R.S.D. less than or equal to 2.0%), and was usable within the PH range 4.0-6.8. The proposed electrode revealed a lower limit of detection of 6.3 x 10(-7) mol dm(-3) and improved selectivity in comparison with the some previously reported DS- ion selective electrodes. The isothermal temperature coefficient of this electrode amounted to - 0.001 VdegreesC(-1). The liquid membrane electrode may find application in the direct determination of SDS by the standard addition method at PH 5.0, and in the physicochemical studies of surfactant solutions. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 40]