Visualizing Events Under Solvent-Gradient and Insights Thereof
This paper describes graphical methods to visualize variations in mobile phase composition inside a chromatographic column under solvent-gradient conditions, and how these variations affect movement of analyte bands. Based on the visualization techniques, the report explains how variations in composition “experienced” by an analyte, which is moving, are different from variations experienced by a static point inside the column. For example, if a linear gradient is created by the system, every point inside the column will experience the same linear variation of composition, although at different times, assuming that the solvent-gradient created at the mixer propagates through the system intact and undisturbed. For an analyte, on the other hand, the variation could be strongly non-linear because normally it travels with varying speed along the column during a gradient run. And because different analytes travel with different speeds, solvent-gradient experienced by the analytes will not be the same, even under the same method condition. Although these events are captured in the fundamental equation of solvent-gradient chromatography and generally understood by researchers working with gradient theories, the visualization methods discussed here may provide a clearer imagery of events for wider appreciation.
KeywordsSolvent-gradient Visualization Travel-time
Helpful discussions with Dr Fabrice Gritti, Dr Martin Gilar and Dr Allen Caswell of Waters Corporation are acknowledged. Thanks to Prof Gert Desmet of Vrije Universiteit Brussel for valuable comments.
Compliance with Ethical Standards
Conflict of interest
The author declares that he has no conflict of interest.
The research described in this publication does not contain any studies with human participants or animals performed by any of the authors.
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