Comparison of the most recent chromatographic approaches applied for fast and high resolution separations: Theory and...

In the last few years, there have been a lot of advances in the field of liquid chromatography (LC) and supercritical fluid chromatography (SFC). The intent of this review is to summarize the available approaches including the use of high mobile phase temperature, extended system upper pressure limit, fully porous particles down to sub-2μm, superficially porous particles (SPP) from 1.3 to 5μm, as well as first and second generations silica-based monoliths. Increasing the mobile phase temperature in LC is one of the most attractive strategies to decrease analysis time, while it is not always the best way to achieve very high plate count. Silica-based monoliths available since 2000, may be more competitive if the upper pressure limit of the column can be extended to 400-600bar (modification of the PEEK cladding). Extending the system pressure in UHPLC beyond 1000bar is a powerful strategy to increase the maximal achievable efficiency in LC, but its impact on throughput remains limited and frictional heating effects should be considered with care. Modern columns packed with SPP introduced in 2007 are attractive in both LC and SFC. Stationary phases packed with 5 and 1.3μm SPP are currently the most promising strategies for high resolution and high throughput separations in LC, respectively. In SFC, columns packed with 2.7μm SPP particles represent a good compromise between throughput and resolution. Finally, to attain the highest possible kinetic performance in SFC, there is a need to further reduce extra-column band broadening (system dispersion, σext(2)) down to 10μL(2) or less. In addition, the system upper pressure limit should be extended to ∼800bar, to have a sufficient flexibility, particularly when working with a mobile phases containing a relatively high amount of organic solvent (e.g. 20-40% MeOH).