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The sensitive amperometric end-point procedure (Anal. Chem., 23, 1662 (1951)) with an antimony electrode is used in the titrations of acids. The cyclic voltammetric curves of the electrode indicate the possibility of the use of the above method for the titration of acids. The purities of potassium biphthalates (primary standard substances) are determined directly by precise coulometric titration with this end-point location. The standard deviations of the results (99.999%) are 0.007 or 0.008%. The purity of the benzoic acid prepared as the standard material for the calorimeter is also determined by this method. The standard deviation of these results (99.993%) is 0.009%.

Sodium amide was used to convert a microamount of water into ammonia in a carrier gas. The ammonia was then titrated with coulometrically generated hypobromite ions. The reaction between water and sodium amide was completed stoichiometrically, and the reaction rate was considerably promoted by heating sodium amide at 80°C. The sample hydrogen was oxidized with copper(II) oxide at 800°C, and the water thus produced was determined by this method. 0.096–0.665 ml(8.6–59.8 μg) of hydrogen and 0.055–0.465 mg of water in barium chloride crystals were determined within errors of 3.6% and 3.0% respectively. The water adsorbed on the surfaces of the weights was also determined by this method at various humidities.

The purities of tin metals are determined directly by precise coulometric titration. The sample is dissolved with hydrochloric acid in a nitrogen atmosphere. The solution is then introduced into a hot antimony column. The reduced tin(II) ions are titrated with electrolytically-generated iodine. The titration is accomplished in a special cell by the use of which any disturbance of atmospheric oxygen is avoided. The titration efficiency under these acidic media was decreased when the current density was increased more than several mA/cm2. The results obtained by two different analysts for the sample of the pure tin metal (5-nine) were 99.996 and 99.991%. The standard deviations of the results were 0.025 and 0.016% respectively. The tin in the other tin metals and in Zircaloy samples was determined satisfactorily without the use of any experimental factor.