ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Hydration of p-trifluoroacetyl benzoic acid heptyl ester: how it affects analytical characteristics of sulfate selective electrodes based on higher quaternary ammonium salts

Yulya Matveichuk, Yauhen Akayeu, and Evgenii Rakhman’ko

Belarusian State University, Minsk, Republic of Belarus

E-mail: Yu_Matveychuk@mail.ru

Abstract: Potentiometric studies of p-trifluoroacetyl benzoic acid heptyl ester (TFABAHE) and its hydrate in sulfate-selective electrodes based on higher quaternary ammonium salts (QAS) have shown that analytical characteristics of the electrodes deteriorate after 2 weeks. This process corresponds in time with accumulations of TFABAHE hydrate form in the membranes, that is confirmed by IR spectroscopy, thermal analysis, electron microscopy and NMR ¹H spectroscopy data. It indicates that the solvation of sulfate ions with TFABAHE is performed most likely by the trifluoroacetyl carbonyl group carbon atom. The procedures for determination of sulfate ions in mineral water have been proposed.