Zinc-selective membrane electrode based on 5,6,14,15-dibenzo-1,4-dioxa-8,12-diazacyclopentadecane-5,14-diene

A new PVC membrane for zinc ions based on DBDA15C4 as membrane carrier was prepared. The electrode shows a linear stable response over a wide concentration range (5.0 x 10(-5)-1.0 x 10(-1) M) with a slope of 22 mV/decade and a limit of detection of 3.0 x 10(-5) M (2.0 mu g/ml). It has a very short response time of less than 5 s and can be use for at least 11 months without any divergence in potential. The zinc ion-selective electrode exhibited very good selectivities with respect to alkali, alkaline earth and some transition and heavy metal ions and could be used in a pH range 1.5-7.0. It was successfully applied for the direct determination of zinc in a pharmaceutical sample and, as an indicator electrode, in potentiometric titration of Zn2+ ions.