Computer-Aided Separation Optimization in Reversed-Phase Liquid Chromatography

Abstract

Optimization in separation sciences is still an important demand from analysts who look for a desired resolution in minimum time. A brief description of the basic steps of a computer-assisted separation optimization in reversed-phase liquid chromatography is provided on the basis of our work performed in this field in the last two decades. Emphasis is directed to separation optimization of ionized and/or nonionized solutes under both isocratic and gradient conditions involving two chromatographic parameters, eluent organic content and pH. The optimization functions presented in this review offer two different possibilities of selection of optimal separation conditions. In the automatic mode, the optimal separation conditions are determined by maximizing the resolution within elution time preset by the analyst. In the manual mode, when elution is determined by one parameter, the optimal separation conditions are selected from a good appreciation of plots of resolution and retention time of the last eluted solute created as a function of that parameter. In case the elution is governed simultaneously by two factors, manual selection of optimal conditions is also possible but via the corresponding contour plots. The foreknowledge of the precise dependence of resolution and elution time upon one or two retention parameters of interest, provided by a computer-assisted separation optimization method and not by a trial-and-error method, gives chromatographers a feel of confidence for the selection of the optimal conditions for a desired separation. For more complex separations involving a simultaneous optimization of three or even more chromatographic parameters, the optimization algorithm can be used only in the automatic mode since manual selection of the optimal conditions is not possible.