Prediction of Electrophoretic Mobilities. 1. Monoamines
- 1 January 1998
- journal article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 70 (1), 173-181
- https://doi.org/10.1021/ac9706638
Abstract
The mobility of an ion is of fundamental importance in capillary electrophoresis. The size, shape, and other physicochemical parameters of monoamines are determined using molecular modeling. These parameters are used to generate regression expressions to predict absolute (infinite dilution) mobilities. Molecular volume or mass is the strongest determinant of electrophoretic mobility. However, molecular volumes calculated via molecular modeling varied systematically depending on the software used, and so molecular mass is the favored descriptor. Neither the classical spherical (Hückel) nor ellipsoidal (Perrin) models were reasonable predictors of mobility. In accord with empirical expressions, such as the Wilke−Chang equation for diffusion, the absolute mobilities correlate with mass (or volume) to a much greater power than predicted by Stokes's law. Incorporation of the effects of hydration using the McGowan waters of hydration increments further improved the predictions. The best equation for predicting absolute mobilities of monoamines is μ0 = [(5.55 ± 0.73) × 10-3]/[W(0.579±0.026) + (0.171 ± 0.054)H] where W is the molecular weight and H is the mean waters of hydration calculated using the McGowan increments. The uncertainties are the standard deviations of the parameters. This equation yielded an average prediction error of 4.1% for the data set used to generate the expression (literature absolute mobilities for 34 monoamines possessing no other functional groups), 7.2% for an independent data set from the literature (absolute mobilities for seven monoamines possessing other functional groups), and 3.3% for an experimentally determined data set (13 monoamines determined using capillary electrophoresis).Keywords
This publication has 31 references indexed in Scilit:
- Molecular size/shape effects in the separation of the monosubstituted alkyl pyridines using capillary electrophoresisElectrophoresis, 1994
- Optimization of capillary electrophoresis of mixtures of basic peptides and comparison with HPLCAnalytical Chemistry, 1993
- Optimization of pH for the separation of organic acids in capillary zone electrophoresisAnalytical Chemistry, 1993
- Role of charge suppression and ionic strength in free zone electrophoresis of proteinsAnalytical Chemistry, 1991
- The current state of our understanding of ionic mobilitiesPure and Applied Chemistry, 1991
- Ionic mobility. Theory meets experimentThe Journal of Physical Chemistry, 1979
- Molecular volumes and the Stokes-Einstein equationJournal of Chemical Education, 1970
- Electrophoretic Mobilities of Peptides on Paper and their Use in the Determination of Amide GroupsNature, 1966
- Correlation of diffusion coefficients in dilute solutionsAIChE Journal, 1955
- Properties of Electrolytic Solutions. XLVI. Conductance of Long Chain Salts at Low Concentration in Water1Journal of the American Chemical Society, 1950