Computer‐aided selection and optimization of chromatographic columns and conditions for multicolumn analysis procedures

Abstract

Clearly, the usefulness of a computer‐aided column design program will depend on its ability to predict quickly and accurately, a design which will yield chromatograms closely approximating those obtained experimentally. Such a computer model for designing and specifying operating conditions for optimum performance of either single or serially coupled columns with different stationary phases is described herein. Tests have been performed in order to verify the accuracy of the model. In addition to single column optimization and the design of column combinations which can be used to achieve separations difficult or impossible on a single phase alone, the model has proven quite useful as an aid to the design and development of multicolumn analysis procedures that involve critical timing of valve‐switching sequences.

GC models for separation optimization in pressure-tuneable tandem capillary columns operated isothermally. Part 1: Theoretical aspects

“…As from 1973, a few eminent researchers showed how the theoretical description of a tandem‐column assembly may be obtained by combining fundamental relationships on GC with very few basic equations valid for multichromatographic systems. Their mathematical analysis was applied to tandem‐column systems made up of two chromatographic columns that can differ from each other for the polarity of the stationary phase and, if necessary, for their geometric characteristics.…”

“…In the 70s, the diffusion of the first electronic devices for the dynamic control of gas flow and pressure made an innovative approach possible. Selectivity was tuned by adjusting carrier gas pressure at the junction of two capillary columns containing different stationary phases and connected in series . This new technique, called “selectivity tuning” or “tandem‐column chromatography,” made use of differential control of carrier gas velocity in the two capillary columns to produce a gradual change of residence times in each column.…”

A Strategy for the Simplification and Solution of Complex Chromatographic Analysis Problems Utilizing Two-Dimensional Mapping of Retention Indexes Followed by Computer Modeling of Heart Cuts from Serially Coupled Columns Containing Different Stationary Phases

“…In this procedure the separation factor for the most difficult to separate pair (whose identity may change as the phase mixture is varied) is plotted versus the mole fraction of the phases used for the separation. This tool has been incorporated into the computer program [2,18] and generated the diagrams shown in Figure 3 for the separation of all fifteen components (lower curve) and for the separation of only the key components from each other and the other interferents (upper curve).…”

Fundamental Relationships of Chromatography

“…[121,[174][175][176]. The analysis time and column pressure drop will increase proportionately with column length while resolution will increase only as the square root of the column length.…”

“…The residence time of the sample in the two columns can be adjusted by changing the relative column lengths, by adjusting the average linear velocity of the carrier gas in the two columns to preselected values, or by operating the columns at different temperatures in a dual oven gas Chromatograph [174][175][176][177][178]. For practical convenience, the junction between the two columns is both pressure and flow controlled with also, for convenience of accurately setting the experimental conditions for the first column, the possibility of diverting a fraction of the sample from the first column to a detector.…”