The advances in particle and column manufacturing (nowadays offering sub-2mm fully porous and core-shell particle columns capable of withstanding 1000 bar inlet pressure) that have been made in the past decade have opened the road towards unprecedented separation speeds. Using these columns in combination with the high-temperature and ultra-high pressure modes in which modern day HPLC instruments can be operated, one frequently runs into a situation wherein the quality of the columns and separation methods has improved to such an extent that the quality of the instrument (and its contribution to the band broadening) has become the limiting factor. Also practical constraints such as limitation in flow-rate or maximal column length significantly reduce the potential of any chromatographic technique.

The present tutorial will present an overview of the underlying theory needed to understand the influence of the instrument design (system and dwell-volume, oven design and operating mode, flow rate and pressure range of the pump) on the observed column performance. This will be done by reviewing some of the most important classic and recent literature on the topic. In addition, practical examples of separations on conventional as well as state-of-the-art instruments will be given to illustrate the effect of the different contributors.