Carbonate-Selective Electrodes Based on Higher Quaternary Ammonium Salts with Increased Steric Accessibility of the Exchange Site

Abstract

A film polyvinyl chloride (33 wt %) carbonate-selective electrode based on a higher quaternary ammonium salt with increased steric accessibility of the exchange site, 3,4,5-tris(dodecyloxy)benzyl( oxyethyl)₃trimethylammonium chloride (5 wt %), was developed using o-nitrophenyl decyl ether (52 wt %) as a plasticizer and heptyl p-trifluoroacetylbenzoate (10 wt %) as a solvating agent. The limit of detection of hydrocarbonate was 1.9 × 10⁻⁹ M, lifetime was 2.5 months, and the slope of the electrode function was 32.3 ± 0.6 mV/decade. The electrode is selective in the presence of interfering SO₄^2-, Cl⁻, C₂O₄^2-, Br⁻, HPO₄^2-, and NO₃^- ions, which allows its application for the determination of HCO₃^- ions in mineral water.