OPTIMIZATION OF A MULTISOLVENT COMPOSITION IN RPHPLC - GENERALIZATIONTO NONIDEAL PEAKS

When samples contain solutes at very different concentrations, the use of the classical resolution function to express the quality of the se paration does not provide a true measure of peak overlap and is theref ore unsuitable for optimization. Apart from this case, the validity of the optimum is highly dependent on the accuracy of the predicted rete ntion surfaces and it is essential to restrict the parameter space in which optimum performance is sought. As a result, most interpretive op timization procedures become unreliable for optimizing the composition of multisolvent systems in RPHPLC, particularly for non-ideal peaks. These difficulties can be overcome by the method proposed here: the ab ility, by means of a criterion, called GRIT, to select a restricted ra nge of composition in order to enhance the accuracy of the response su rface is developed for non-ideal peaks. The best composition within th is selected range is then determined by using a modified resolution fu nction. The performance of this procedure is discussed with some illus trative examples.