Sol−Gel Modification of pH Electrode Glass Membranes for Sensing Anions and Metal Ions

Abstract

To obtain glass membrane electrodes selective for anions and metal ions, pH electrode glass membranes were modified by a sol-gel method using a quaternary ammonium salt and a bis(crown ether). A chloride ion-sensing glass membrane was designed, in which a pH electrode glass membrane was modified chemically by an alkoxysilyl quaternary ammonium chloride. X-ray photoelectron spectroscopy confirmed the chemical bonding of the quaternary ammonium moiety to the starting glass surface, which afforded the first example of glass-based "anion"-sensing membranes. A neutral carrier-type sodium ion-selective glass membrane was also fabricated which encapsulates a bis(12-crown-4) derivative in its sol-gel-derived surface. Both sol-gel-modified anion and metal ion-selective glass electrodes exhibited high sensitivity to their ion activity changes. The present sol-gel modification paves the way for designing glass-based ion sensors with tailor-made ion selectivities toward anions as well as cations.

Recent Updates of Chemically Modified Electrodes in Analytical Chemistry

“…Nonetheless, selectivity is an important criterion for such studies and always limits the applications. Kimura et al rationalized the pH-sensing electrode using a sol gel-based ionomeric system (tretradecyldimethyl(3-rimethoxysilylproyl)ammonium chloride) and crown ether derivative (bis(12-crown-4-methyl)dodecylmethylmalonate) for simultaneous potentiometric sensing of Na and Cl À ions [84]. Rusling and co-workers introduce polymer pendant type of modified electrode by coating PVP as the underlying support to anchor Ru(bpy) 2 Cl 2 complex [85].…”

Sol-Gel Encapsulation as Matrix for Potentiometric Nitrite-Selective Membranes Doped with Chloro (5, 10, 15, 20-Tetraphenylporphyrinato) Cobalt (III)

“…16) After initial reports of chloride-selective electrodes employing the solgel method, 17,18) the possibility of using a traditional carbonate-selective ionophore, trifluoroacetyl-p-decylbenzene (TFADB), within a sol-gel matrix has also been studied. 19) In the present paper, we report the applicability of the sol-gel matrix in conjunction with Co[TPP]Cl, which is known as a neutral carrier ionophore for nitrite.…”

Supramolecular Based Membrane Sensors

“…A neutral carrier-type sodium ion-selective glass membrane was also fabricated which encapsulates a bis(12-crown-4) derivative in its sol-gel-derived surface. Both sol-gel-modified anion and metal ion-selective glass electrodes exhibited high sensitivity to their ion activity changes [132]. …”