Isochronal optimization : III. Experimental verification

Abstract

The theoretical aspects of isochronal optimization (time normalization) are verified experimentally in the present communication. The variant examined here utilizes simultaneous changes in mobile phase composition and velocity. Two empirical relationships for the capacity factors were examined. From these relationships, predicted resolution surfaces were generated and these were compared with the experimental ones. It was found that quadratic relationships between the natural logarithm of k′ and the mobile phase composition yielded surfaces that resembled the experimental ones most closely. Moreover, it was found that only three experiments, with three different mobile phases, were sufficient to calculate the resolution surface with adequate accuracy. Isochronal lines (resolution lines with constant analysis times) were generated from the predicted data and compared with experimental isochrons. The agreement between the two sets of lines was very good. Based on three experiments it is possible to predict experimental conditions that will yield better resolution without increasing the analysis time.