Computer-based numerical integration for the calculation of retention times in gradient high-performance liquid chromatography

Abstract

An approach to the calculation of solute retention under gradient elution conditions using numerical approximations on a DEC VAX 11/780 computer is presented. This approach eliminates the need for exact solutions of the inherently complex gradient integrals. The programs developed can be used for any solvent composition vs. solute capacity factor or solvent composition vs. time relationships and are, therefore, universal in nature. Gradient microbore HPLC in the reversed-phase mode was used to demonstrate the accuracy of the approach. The assumption of a quadratic dependency between k' and solvent composition allowed for the least-squares fitting of solute isocratic retention with a minimal number of experiments. By use of this approach and the corresponding FORTRAN program, prediction of solute retention under complex multiple-linear gradient shapes was achieved with an accuracy of better than 5%. 20 references, 4 figures, 6 tables.