Cetyldimethylethylammonium-selective PVC electrode based on its ion-associate with phosphotungstic acid

A PVC membrane electrode selective for cetyldimethylethylammonium (CDEA) io n was prepared. The active element is a plasticized poly vinyl chloride mem brane containing a dissolved ion associate complex of CDEA with phosphotung stic acid (PTA). The electrode showed a near-Nernstian response within the CDEA(+) concentration range 2.34 x 10(-6) to 1.96 x 10(-4) M at 25 +/- 1 de greesC, good selectivity, and is usable within the pH range 3.5-9.0. The is othermal temperature coefficient of the electrode amounted to -0.00012 V/de greesC. The electrode has been used for the direct determination of cetyldi methylethylammonium bromide either by the standard addition method or by po tentiometric titration against PTA.