Potentiometric titration of organic cations precipitated by tetraphenylborate

Summary Sodium tetraphenylborate has been used for the potentiometric precipitation titration of some water-soluble organic cations, mostly those containing a quaternary ammonium group. Emf's were monitored with a fluoroborate ion-selective indicator electrode and a double-junction reference electrode. Other liquid-membrane electrodes, such as the perchlorate and nitrate, also respond to the cations investigated. The solid-state cyanide electrode responds to those cations yielding potentiometric breaks of > 70 mV with the fluoroborate electrode. The following compounds were examined: procaine, diphenhydramine, chlorpheniramine, methylene blue, dimethyl yellow, benzidine, pyridine, acetylmethylcholine, thiamine.This paper was presented at the International Symposium on Electroanalysis in Cardiff, England, on April 13, 1981