A measure of the solid-solution extent useful for crystallisation resolution studies

The ratio of partition coefficients of molecular components between crystal and liquor phases gives a measure of the solid-solution extent, termed D. This measure is considered useful to compare the results of resolution experiments and to make predictions of the crystal composition obtained under different starting compositions and crystal yields. The calculations show that a small extent of solid solution (e.g., 0.1%) can have a noticeable effect, and that the maximum efficiency of a resolution in certain cases is determined by the solid-solution extent rather than by the eutectic composition with the opposite isomer.