Determination of component concentrations in mixtures of weak and strong acids and bases by linear algebraic methods.

A general expression for transforming potentiometric titration curves of mixtures of weak acids into a system of linear equations is derived. The solution of the linear equations gives directly the concentrations of the components. This linear transformation method is illustrated by the analysis of mixtures of weak acids with overlapping dissociation equilibria. The possible presence of a strong acid or strong base in the mixture can also be detected and its concentration simultaneously determined. The method can also be used for analysis of an ampholyte and solutions containing a weak acid and its conjugate base. For example a mixture of hydroxyacetic acid (pK approximately 3.6), acetic acid (pK approximately 4.6) and hydroxylamine hydrochloride (pK approximately 6) was analysed in the presence of strong acid with an average relative error of approximately 2%.

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