Parallel segmented flow chromatography

Abstract

It is now well understood that chromatography columns are heterogeneously packed. During the column packing process stationary phase particles close to the wall experience more friction that those in the centre of the bed. This creates a bed that is more permeable within its core than the region closest to the column wall. The consequence of this heterogeneity is that it creates a solute band that somewhat resembles a bowl where the section of the band that migrates through the column wall region travels slower than the section of the solute band that migrates through the more permeable column core. Now consider the scenario where multiple cup-like solute bands migrate through a column, it follows that it requires many more theoretical plates to separate two closely eluting bowl-like bands than it would if the bands were of a rectangular plug flow profile. However, if it were possible to detect only the surface of the central region of these bowl-like bands they could be separated more efficiently. This has been accomplished in two ways; firstly end- column detection can be used where a detector is located at the centre of the column outlet, before the frit. Secondly, the solute can be injected in such a manner that it migrates solely through the column core region. This can be accomplished by injecting the sample into the core region of the column using a syringe that is embedded within the stationary phase in a technique known as infinite diameter chromatography. Despite the success of end-column detection and infinite diameter chromatography in improving efficiency it is not possible to use these techniques with commercially available instrumentation in a routine manner. Recently a novel column format, which achieves the benefits of end column detection has been introduced. This new column format is referred to as Parallel segmented flow chromatography. The parallel segmented flow chromatography column uses a new design of fitting, known as the active flow technology fitting, which permits the separation of the eluent migrating through the column core from the eluent travelling through the wall region. The PSF column has flow segmentation at the column outlet only.Since parallel segmented flow chromatography is a recent development, the characterisation of the PSF column is the focus of this thesis. As such this thesis will lay down the foundations for the operation of parallel segmented flow chromatography columns to facilitate their wider application in future research.

Date of Award	2013
Original language	English