TOLUIDINE BLUE SELECTIVE PLASTICIZED POLY(VINYL CHLORIDE) MEMBRANE-ELECTRODE FOR COLLOIDAL TITRATION

A Plasticized Poly(vinyl chloride) membrane electrode was applicable to colloidal titration without selective substances. The change of potential in the end-point, however, was too small to measure accurately. We prepared a new type of electrode with toluidine blue as an indicator. It was found that the electrode was quite useful to the colloidal titration. At the end-point a large change of potential was observed, and a small amount of polyelectrolyte anion could be titrated directly. Potassium poly(vinyl sulfates) was titrated with errors not more than 0.7% of r.s.d. in the amount of several micro chemical equivalents. This method was used to measure some poly(isoplene sulfonates) used as a dispersant polymer and its results agreed with that of acid-base titration.