Knox-Saleem kinetic performance limits in liquid chromatography. Part 2: Alternative interpretation – No upper limit to separation performance

In Part 1 of this series, the original Knox-Saleem study of the effects of column dimensions and operational conditions on the column performance was reformulated in contemporary language and expanded to a broader class of the columns and their operational conditions. However, the view of the effects in Part 1 was the same as in the original Knox-Saleem study. In both cases, the effects were treated as the performance limits. The following issues were addressed. What is the shortest time for obtaining a required separation performance if column pressure is limited? What is the highest separation performance achievable in a given time at a given pressure? And so forth. While addressing these issues, it has been established in Part 1 that there is no fundamental limit to the separation performance of any given column structure. For example, any separation performance of a packed column (e.g., any peak capacity) no matter how high can be obtained at any pressure no matter how low as long as the analysis time is acceptable. This and similar factors suggest that the effects of a column parameters and operational conditions on the column performance might be viewed not as the limits, but as the tradeoffs between the parameters, the operational conditions and the performance. This approach is developed in this report. The properties of the tradeoffs are evaluated, and potential performance of several column structures is compared.