OPTIMIZATION OF SELECTIVITY IN HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHYUSING DESIRABILITY FUNCTIONS AND MIXTURE DESIGNS ACCORDING TO PRISMA

A computer program for the mobile phase optimization of high-performan ce liquid chromatography (HPLC) is described. The desirability functio n technique combined to the PRISMA mixture design was employed to enha nce the quality of HPLC separations. The use of statistical models to predict the behaviour of retention times (t(R)) and band broadening at the different eluent compositions obtained by PRISMA was examined for dansyl amides and coumarins. The study showed that the dependence bet ween the eluent composition and t(R) values of dansyl amides and couma rins can be expressed using quadratic regression models with a high de gree of accuracy. Band broadening given by means of the band width at half-height (w(h)) war described by a linear regression model. Both mo dels were used in calculating and predicting the resolution (R-s) in v arious solvent combinations. The desirability function converted the c alculated (R-s) value into the desirability value (D), and the overall optimum was then defined by means of the overall desirability. The op timal eluent mixtures for the separation of compounds were easily read from the contour plot inside the horizontal plane of the PRISMA model . A good separation was achieved using the optimized solvent combinati on. Depending on the aims of the optimal separation, the program allow s either optimization of critical pairs or achieving the overall optim um giving a reasonable separation for as many compounds as possible. ( C) 1998 Elsevier Science B.V.