Voltammetric Investigation of the Response Mechanism of the Ion-Selective Electrodes Based on the Polymer Modified with Poly(oxyethylene) Derivatives in Acetonitrile

Abstract

The voltammetric behavior of barium and lithium ions in acetonitrile (AN) was studied at polymer membrane ion-selective electrodes which showed Nernstian responses to those metal ions in AN, in order to elucidate the mechanism of their potentiometric responses. The membrane electrodes consisted of polyacrylamide coupled to such poly(oxyethylene) derivatives as tetraethylene glycol monododecyl ether, dibenzo-18-crown-6, and cryptand222B and coated on platinum or gold disk. The cyclic voltammograms for barium and lithium ions, recorded repeatedly after setting the electrodes at the rest potentials, showed a cathodic peak at −1.5±0.2 V vs. Ag/0.01 M Ag+ (AN). The cathodic peak current (icp) decreased markedly between the first and second scans, but reached a steady value after the third scan. The icp values after the third scan were diffusion controlled and considered to be due to a transfer of the metal ions from the solution into the membrane. The differences in icp between the first and the third scans were proportional to the potential scan rate and attributed to a transfer of the metal ions which had been accumulated at or near the surface of the membrane by combining with the functional groups of the polymer. The accumulation occurred rather slowly and saturated with time. Based on the fact that the response processes of the ion-selective electrodes were very much similar to the accumulation processes, the response mechanism of the ion-selective electrodes is discussed.

Development and application of poly(acrylamide) membrane ion-selective electrodes for use in dipolar aprotic solutions

“…In our research, cyclic polyethers (crowns) were covalently bound with hydrophilic PAA so that they could be used in nonaqueous solution. We have deduced that the electrochemical selectivity and thermodynamic response behaviors of PAA-crown membrane electrode were mainly due to the complex formation of metal ions (alkali metal and alkaline earth cations) with crown at the membrane/solution interface [28]. The potential response mechanism of PAA-acyclic polyether electrode was similar to that of PAA-crown ether electrodes.…”

“…The carboxyl-modified FAA was used to conjugate with various host compounds (Host), which are able to reversibly react with the interest ions in nonaqueous solutions, to produce host compound modified PAA. The typical host compounds used in our research are shown in Table 1 [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

Development and Application of Ion-Selective Electrodes in Nonaqueous Solutions

“…A study of a potential establishment site has also been reported. 19 Previous papers [20][21][22] are available for understanding certain kinds of chemical and physical properties of a hydrophilic poly(acrylamide) (PAA) membrane.…”

“…In these reports, voltammetric investigations concerning the response time 20 and the micro array arrangement 21 of electrodes and conductometric characterization about the properties of ion-transport across a 22 were described. Studies that aimed to determine the successive complex formation constants between a monovalent cation and solvent molecules using a monovalent cation sensitive glass electrode (Beckman Co. Ltd.) were reported.…”

Electrochemical Behavior of Catechol and 3,4-Dihydroxytoluene in Acetonitrile at a Platinum-Disk Electrode Modified with a Tyrosinase Containing Polyacrylamide Film

“…We have found from the results obtained in our previous research 7 that an ionophores-conjugated PAA-coated platinum disk electrode could be used for obtaining voltammetric information on cations and anions in AN. 8,9 It will be worth while to develop new types of enzyme electrodes for use in dipolar aprotic solvent systems, in which we can dissolve many hydrophobic substrates, extend the potential windows, trap intermediate reaction products like radicals, and, as a result, trace new enzymatic activities and the reaction mechanism. Thus, we may expect to obtain new sensing systems.…”