Alternating current tensammetry of tetraphenylborate (TPB) and its application for potassium determination

Alternating-current polarography of tetraphenylborate ion (TPB) in acetate buffer (pH 4 to 5) or 0.1 to 0.5 M NaCl produces a characteristic tensammetric (pseudocapacitive) peak at -0.95 V (vs. SCE). Within a limited range (till about 0.2 mM), the tensammetric peak current is proportional to the TPB concentration but it levels off at higher concentration. TPB concentration can also be determined within 5 to 50 muM by measuring the capacity current at 0.4 V or the differential pulse polarographic peak current at -0.85 V. The tensammetric peak current was used to determine the solubility of potassium tetraphenylborate in acetate buffer and sodium chloride solutions., Also, a method for amperometric back-titration of potassium ion was worked out and applied to the analysis of mineral water.