New Selenite Selective Electrodes Based on Higher Quaternary Ammonium Salts

Abstract

A new film selenite selective electrode has been developed, with the following membrane composition: (3,4,5-tris-dodecyloxybenzyl)dioxyethyl trimethyl ammonium chloride (5% w/w) as an electroactive component, (poly)vinyl chlorid (33% w/w) as a membrane matrix, 1-bromonaphtalene (42% w/w) as a plasticizer, 4-trifluoroacetylbenzoic acid heptyl ester (20% w/w) as a solvating additive. The electrode has a wide activity range - 7.5×10–7- 10–2 Ì Na2SeO3; slope 29.0±0.4 mV decade–1; detection limit 4×10–7 M Na2SeO3; working pH range 8.6 - 9.7; the potential drift 1.3 mV h–1; the response time 25 s; lifetime up to 3 weeks without observing any deviation, and is selective to selenite ions in presence of chloride, bromide, sulfate and selenate ions.