Importance of instrumentation for fast liquid chromatography in pharmaceutical analysis

• A suitable chromatographic system has to be employed to take the full benefits of modern LC columns.
• Extra-column band broadening and gradient delay volume have to be minimized.
• The upper pressure limit of UHPLC systems is less critical in the case of fast-LC separations.
• Acquisition rate is sufficient with spectroscopic detectors but much more critical with MS devices.
• During the last few years, column technology has evolved faster than instrumentation.

In the last decade, an important technical evolution has occurred in pharmaceutical analysis with numerous innovative supports and advanced instruments that have been proposed to achieve fast or ultra-fast separations in LC with an excellent sensitivity and ease of operation. Among the proposed strategies to increase the throughput, the use of short narrow-bore columns packed with sub-3 μm core–shell and porous sub-2 μm particles have emerged as the gold standards. Nevertheless, to take the full benefits of these modern supports, a suitable chromatographic system has to be employed. This review summarizes the instrumental needs and challenges in terms of extra-column variance, dwell volume, maximum system pressure, detector data acquisition rate, and injection cycle time. In addition, because of their reasonable pressure drop, the use of columns packed with sub-3 μm core–shell particles on a conventional LC instrument is discussed in detail. A methodology is proposed to check the compatibility between stationary phase and instrument, and some solutions are proposed to improve the performance of standard instruments.Finally, because the column technology is evolving faster than instrumentation, it is nowadays possible to purchase short, narrow-bore columns packed with 1.3 μm core–shell particles. Micro columns (1 mm I.D.) packed with 1.7–1.9 μm porous particles are also available from several providers, which limit frictional heating effects and reduce solvent and sample consumption. However, it remains difficult to find instruments compatible with such column geometries and a severe loss of performance may be observed due to the system itself.

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