Computer simulation depicting column temperature—solute retention relationships in gas chromatography is a potentially effective instructional tool and can reinforce theoretical concepts presented in the classroom. The role of computer simulation of gas chromatographic separations in an academic laboratory is described for simple mixtures of alcohols and hydrocarbons for which retention data and chromatograms are accurately predicted. The technique is also illustrated for a more complex sample, peppermint oil, where computer-generated chromatographic data compare favorably with the corresponding experimental data. The approach can be incorporated into presently conducted experiments in the analytical or organic chemistry laboratory and is applicable for both isothermal and temperature-programmed separations.

A mixture of ten compounds with an overlapping peak pair was analysed with a 90-min elution gradient. To improve the separation, two reversed-phase gradients differing by a factor of 3 in their run times, were applied. Contrary to expectation, two peak pairs were less well separated in the gradient run with the lower slope. The relative resolution map provided a rapid solution to the problem: a gradient with 16-min run time gave the best separation of the mixture. The simulated chromatogram was verified experimentally. The differences between the predicted and experimental retention times averaged 0.03 min. Further improvement was obtained using a segmented gradient, which adequately separately all peaks in only 9 min.

The method described in this paper was developed with the help of the gradient elution technique. With known dwell volume, gradient elution could be used in routine work without problems. Computer supported HPLC-method development allows the control of a large number of experiments on the screen and verification only of the experimentally promising ones. The method has been developed in 3 days and is approved in practice. With the method, 5 by-products of the synthesis of Atenolol could be identified and quantitatively determined.

Summary of symposium on computer-assisted method development from the 1991 Pittsburgh Conference.

Application of DryLab GC to wide range of environmental, pharmaceutical, and process samples.

An experimental study was carried out for the separation of a series of homologous 2-ketoalkanes by reversed-phase gradient elution. Both linear and non-linear gradients were used. Computer simulation was applied to these same separations, and comparisons were made between experimental and predicted results (values of retention time, retention time difference and bandwidth). Errors in the predicted separation were generally small and similar for both linear and non-linear gradients. Somewhat larger errors (retention time differences) were found in non-linear gradient separations for bands eluting after a change in gradient steepness. This can be attributed to the dispersion (rounding) of the gradient as it passes through the high-performance liquid chromatographic equipment. Computer simulation was demonstrated to provide predictions that are adequate for the purposes of developing an optimized gradient separation.