Dwell Volume And Extra-Column Volume: What Are They And How Do They Impact Method Transfer?

Method transfer or method scaling across different instrument platforms can be affected by both dwell volume and extra-column dispersion. Each characteristic will have a very different effect on the chromatographic separation. Dwell volume is the volume required for the change in gradient to reach the column, or the volume difference between the point of mixing and the head of the column. Dwell volume impacts the retention times of a gradient separation, but can also affect selectivity, particularly for early eluting compounds. Extra-column dispersion is a measurement of the broadening of a peak that occurs between the injector and the detector and excludes the column. Extra-column dispersion or volume impacts peak width, resolution, and the overall efficiency of a separation. In this review, the differences of these attributes across a variety of instruments will be examined, specifically for their impact on method transfer. By characterizing the system and understanding the differences, strategies can be undertaken to increase the success of method transfer.