Neue Methoden zur spektrophotom etrischen pK-Wertbestimmung, I / New Methods for Spectrophotometric Determination of pK-Values, I
Open Access
- 1 August 1974
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung B
- Vol. 29 (7-8) , 500-513
- https://doi.org/10.1515/znb-1974-7-811
Abstract
By means of a spectrophotometric titration at many wavelengths it is possible to determine the uniformity („Einheitlichkeit“) of the system, respectively, the number and kind of dissociable groups. Isosbestic points, absorbance-, absorbance-difference diagrams and other graphs are used for the analysis of spectrophotometric titration data. Different methods for determination of absolute pK-values of one-step titration systems are compared critically. To avoid the problems of electrometric pH-measurements some new methods are proposed to evaluate relative pK-values ( Δ pK -values) by means of a simultaneous titration of a protolyte together with a standard substance. The efficiency of these relative methods is demonstrated using two compounds with a very small pK-difference (o- and p-nitrophenol, Δ pK = 0.1). The results are controlled by simulation with a digital computer.Keywords
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