Effects of peak tailing on computer optimisation procedures for high-performance liquid chromatography : II. An optimisation routine for tailed peaks

Abstract

An optimisation program is proposed as a means of compensating for the loss of resolution resulting from peak tailing. A mobile phase search area of ternary compositions of water with two of the three solvents, methanol, acetonitrile, and tetrahydrofuran, is defined by isoeluotropic binary mobile phases of water with each of the above three modifiers. Retention and peak shape (τ/σ) data are obtained for each solute in the mixture to be separated, using the three isoeluotropic binary mobile phases. These data are used to interpolate retention and peak shape data for intermediate ternary mobile phases. The area overlap for each peak pair is calculated, and the resolution of a pair of Gaussian peaks with the same degree of area overlap is determined. This value is then used for calculation of an optimisation criterion and the ultimate selection of the optimal mobile phase. The program was computer-validated by using a hypothetical case. It was then experimentally tested by using a mixture of six compounds, giving both symmetrical and tailed peaks. In both cases, the use of the proposed program resulted in the selection of a mobile phase that gave a chromatogram superior to that obtained without considering peak tailing effects.