Molecular size/shape effects in the separation of the monosubstituted alkyl pyridines using capillary electrophoresis

A series of monosubstituted alkyl pyridines have been used to investigate the presence of molecular size/shape effects in capillary electrophoresis and the applicability of various descriptors in discriminating not only between derivatives of differing chain length but also between positional isomers. Although van de Waals' radii and Offord's parameters are extremely good descriptors in predicting the relative mobilities of the derivatives, a further descriptor involving length and/or diameter of the molecule is necessary for discrimination between the positional isomers.