Liquid purification or separation – With means to add treating material – Chromatography
Patent
1997-03-04
1998-06-30
Therkorn, Ernest G.
Liquid purification or separation
With means to add treating material
Chromatography
2105021, 210635, 210656, B01D 1508
Patent
active
057728755
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a column for liquid chromatography.
DESCRIPTION OF THE PRIOR ART
In liquid chromatography on a porous matrix, a liquid in which a compound is dissolved is allowed to pass the matrix with the compound passing through one or more adsorption/desorption stages in the matrix.
Liquid chromatography matrices normally consist of particles (e.g. beads) which are packed to form a bed in a column tube. The bed is normally held in place in the tube with the aid of two adaptors (plates) which each cover a respective end of the bed and therewith also the cross-sectional area of the column tube. One of the adaptors will normally include an inlet for eluant which prior to penetrating the bed passes through a distributor or spreader which distributes the flow of eluant uniformly over the end-area of the bed. The distributor may have a more or less sophisticated construction. Typical distributors are filter papers, plates/discs in which a large number of holes are disposed uniformly across the plate/disc. In some cases, there is used a central inlet from which there extends a system of passageways which function to distribute the liquid to the distributing holes in the plate.
In order to minimize diffusion and zone broadening during a chromatographic process, the distributor plate is placed in abutment with the inlet area of the matrix bed. This eliminates the risk of particles swirling up from the bed. One drawback with packed chromatography beds is that the beds readily subside such as to form cracks, particularly in conjunction with changes in the rate of flow of the eluant, or when the matrix dries out.
An alternative to matrix beds which consist in packed particles is found in the so-called continuous matrices (also called monolithic matrices) which have been porous. This type of matrix does not tend to form channels as a result of subsidence or settling of the bed. By continuous (monolithic) matrices is meant matrices which are intrinsically coherent. Matrices which consist of packed membranes or filters are not monolithic.
PROBLEMS ENCOUNTERED WITH THE KNOWN TECHNIQUE
It has been found that when conventional distribution techniques are applied to continuous matrices, it is difficult to achieve uniform penetration of the eluant across the end-area of the matrix. The eluant readily penetrates the matrix in the vicinity of the distribution holes but scarcely spreads to those parts of the matrix which lie between said holes. This results in mutually parallel, channel-like flows in the matrix and to a low matrix efficiency, which in turn results in low numbers of theoretical plates or low elution volumes (V.sub.e) and also in unfavourable symmetry factors (symmetry factors at 10% of the peak height and defined so that the highest symmetry factor corresponds to 1). The problem is most accentuated in matrices which produce low counter-pressures, i.e. macro-porous matrices of large pore volumes and large pores.
THE INVENTION
It has now been found that the number of theoretical plates, elution volumes and symmetry factors can be improved by providing a liquid gap between the matrix and the distributor during the chromatography process. The positive effect thus achieved is because when the liquid penetrates into the matrix, there is created a continuous layer across the matrix end-area.
The inventive liquid chromatography column is constructed from a column tube which includes a chromatography matrix and a distributor or spreader placed adjacent the inlet and functioning to distribute the incoming liquid. The column is characterized in that the matrix is monolithic and porous and in that as the liquid passes through the matrix, there is present between the matrix and the distributor a gap which does not contain matrix material. The remainder of the column may be of known design. The width of the gap is such as to impart improved properties to the column with respect to number of theoretical plates, symmetry factors and elution volumes in comparison with the case when t
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Eriksson Eva
Pettersson Conny
Porrvik Ingrid
Amersham Pharmacia Biotech AB
Therkorn Ernest G.
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