Potentiometric analysis of mixtures of acids or bases

Earlier proposed a general approach using data mV/mL from a potentiometric titration is tested for the quantitative determination of mixtures of mono- and poly-protic substances. The method is based on the treatment of the primary data with nonlinear regression procedure using commercial software which gives directly the analytical result. A general formula valid for every type of acid base titration (even mixtures of mono- and poly-protic substances) is used as a direct input with the applied software. Along with the analytical concentration, some specific parameters of the analyzed system are also determined (pK-values, Eo ¢, pKw). The primary data mV/mL are transferred into pH/mL data using a self-calibration procedure, hence no preliminary pH-calibration of the glass electrode cell is necessary. The applicability of the method is proven to be correct by the analyses of a number of mixtures of mono- and poly-protic substances. The method is applied also in non-aqueous solvents and a number of sparingly soluble in water organic acids and bases have been determined successfully

Author(s): Vania N. Maslarska, Jasmina D. Tencheva , Omortag B. Budevsky

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