Selectivity of Membrane Electrodes Based on Derivatives of Dibenzyitin Dichloride

Abstract

Selectivity properties are established for membrane electrodes prepared by Incorporating bls(p-methylbenzyl)tin dichloride, dibenzyitin dichloride, and bls(p-chlorobenzyl)tin dichloride In plastlclzed polymer membranes. These electrodes display an unusually high level of selectivity for dibasic phosphate over many common anions. Electrodes prepared with the p-chloro derivative possess the best detection limit and the highest degree of selectivity for phosphate. Selectivity coefficients are calculated for phosphate relative to the following group of anions: salicylate, benzoate, thlocyanate, iodide, nitrate, bromide, chloride, acetate, fluoride, pyrophosphate, arsenate, adenosine 5′-cyclic monophosphate, adenosine 5′-monophosphate, adenosine 5′-dlphosphate, and adenosine 5’-triphosphate. Tin-carbon hyperconjugation within the organotln compound is hypothesized to be critically important in the selective response to phosphate. Enhancement of tin-carbon hyperconjugation by Increasing the electron-withdrawing power of substituents on the benzyl ring is predicted to provide even higher levels of selectivity for phosphate. © 1991, American Chemical Society. All rights reserved.