Potentiometry of Anionic Polyelectrolytes by Quaternary Ammonium Ion‐Selective Electrode with Quaternary Ammonium Ion Added as Probe

Abstract

For potentiometric determination of anionic polyelectrolytes (APEs), the free concentration of water-soluble quaternary ammonium cation (QA þ ) added as a probe was measured with a quaternary ammonium ion-selective electrode. The optimized detection of polyacrylate as one example of APEs demonstrated that the quaternary ammonium ions with a single alkyl group > C 15 had large potential changes (À 80 mV for C 16 and À 130 mV for C 18 ) within a concentration range of 10 À6 -10 À4 mol dm À3 . The response was rapid (several minutes) and independent of pH > 8 and showed no hysteresis. APEs with other anionic functional groups, for example, heparin and poly(4-styrenesulfonate), were also detected.

Penetration of weakly acidic polyelectrolytes into PVC membrane containing quaternary ammonium salt for potentiometry both by ion exchange and by coextraction with proton

“…In order to overcome the drawbacks of this transient method and achieve reversible detection, the carriers consisting of both lipophilic cations and anions were adopted, in conjunction with other driving forces for induction of the phase transfer of PEs [6][7][8][9][10][11][12][13] or with some probes [14]. It was revealed that the PEs were not fully neutralized by the carriers and that the resulting hydrophilic complexes were occasionally not transferred into the bulk of the organic phase but were rather adsorbed onto the interface with the use of such lipophilic salts [6][7][8][9][10][11][12][13].…”