Extra-column broadening in modern UHPLC instrumentation

With the introduction of sub-2μm (superficially) porous particle around 15 years ago, significant improvement in separation speed and resolution became possible. These small particles allowed the use of shorter columns and the use of higher flow rates and were often packed in smaller ID column to avoid thermal effects (viscous heating), reduce solvent consumption and improve compatibility with MS (lower flow rates). These high performance small volume column are however very sensitive the dispersion occurring in the rest of the fluidic path of the instrument such as injector, mobile phase preheater, connection tubing and the detector cell or interface to e.g. MS. It was therefore not possible to use these narrow bore column on ‘standard’ HPLC instrumentation, as they required the use of so-called ultra-high performance instrumentation (UHPLC) that not only have a higher maximum operating pressure, but also have reduced extra-column dispersion.
After introducing the importance and consequences of extra-column dispersion, this tutorial will highlight the different contributions to extra-column broadening occurring in modern UHPLC instrumentation. Methodologies and the pro- and cons to estimate the amplitude of extra-column dispersion are critically reviewed and some easy hands on test to reduce and optimize your system configuration are provided.