1985 Volume 34 Issue 1 Pages 40-43
The cyanine dye Platonin, which has two quarternary ammonium moieties, was found to form a 1 : 2 complex with tetraphenylborate. This complex is scarcely soluble in water and alcohols, unlike Platonin and tetraphenylborate themselves, and is precipitated quantitatively. Thus Platonin can be determined by titration with tetraphenylborate by recording the conductivity of the solution under conditions where Platonin and tetraphenylborate are completely soluble and the complex is insoluble : titration of a solution of Platonin in 60 %(v/v) aqueous methanol with aqueous tetraphenylborate solution at a rate of about 1 ml/min was found to give the best results. Iodide contained as counter ions and a contaminant in Platonin had no effect on the titration. This method is simple and accurate for determination of Platonin.
