Dead volume (chromatography)

In chromatography, the dead volume (synonymous flow volume ) denotes the volume not involved in a separation .

properties

A separation column contains a defined volume of the separation medium ( stationary phase , column bed ) in which the chromatographic separation takes place. The dead volume is the difference between the total volume V ₀ and the volume of the separation medium. It includes the volume in front of and behind the stationary phase as well as the volume between the particles of the stationary phase and in their pores . With the size of the dead volume, the separation becomes more blurred, the band width increases and peaks that extend towards the rear ( tailing ) arise . The time t ₀ that an analyte needs to migrate through the column without interacting with the stationary phase is referred to as the dead time or flow time and is dependent on the flow rate v.

${\displaystyle t_{0}={\frac {V_{0}}{v}}}$

In most chromatography variants, the first and smallest analytes elute after the dead volume, whereas in size exclusion chromatography the dead volume is determined using very large molecules.

literature

• Ralf Goedecke: Fluid Process Engineering. John Wiley & Sons, 2011, ISBN 978-3-527-33270-0 , pp. 403-406.
• Daniel C. Harris: Textbook of Quantitative Analysis. Springer-Verlag, 2014, ISBN 978-3-642-37788-4 , p. 690.

Individual evidence

1. ↑ Veronika R. Meyer: Practice of high-performance liquid chromatography. John Wiley & Sons, 2009, ISBN 978-3-527-32046-2 , p. 41.
2. ↑ Mark Helm: Instrumental bioanalytics. John Wiley & Sons, 2013, ISBN 978-3-527-66204-3 , p. 150.