Ion-Selective Electrodes Based on Polyvinyl Chloride Modified by p-(Trifluoroacetyl)Benzoate Groups

Resumo

Ion-selective electrodes (ISEs), reversible to hydrophilic sulfate, hydrophosphate, and sulfide ions, are developed based on modified polyvinyl chloride (MPVC), combining the functions of a polymer matrix and a neutral carrier. A procedure for the synthesis of MPVC is described, which consists in grafting p-(trifluoroacetyl)benzoate groups to PVC. Previously, ISEs of this type contained PVC as a basis and p-(trifluoroacetyl)benzoic acid heptyl ester (p-TFABAHE). The use of MPVC significantly increases the lifetime of these ISEs by preventing changes associated both with the dissolution of p-TFABAHE (for -SE and S^2–-SE, working in alkaline media) and with the crystallization of the hydrate form of p-TFABAHE on the surface of the -SE membranes working in acidic media.