A facile method of curve fitting of potentiometric acid-base titration data of very weak acids and bases

A new procedure of potentiometric acid-base titration and curve fitting is described for determining very weak acids and bases. Based on specific properties of acidity of basicity of the solution titrated after the very weak acids or bases have been half neutralized, the concentration of proton or hydroxyl in the solution is measured by a simple calibration curve method. The measurement is not affected by carbon dioxygen under experimental conditions. The selections of weighting factors and experimental points are discussed. The procedure is examined with simulated data. Some very weak acids and bases such as ammonium chloride, boric acid, phenol, aniline, sodium acetate, hexamethylenamine and sodium carbonate are determined by the method described in the paper. The results show that it is possible to determine the very weak acids and bases with a satisfactory accuracy and precision.