Liquid purification or separation – Processes – Chromatography
Patent
1996-09-24
1998-02-03
Therkorn, Ernest G.
Liquid purification or separation
Processes
Chromatography
2101982, 210450, 96101, B01D 1508
Patent
active
057140740
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a column for liquid chromatography, which includes a column tube intended to be filled with a separation medium, and inlet and outlet means. The invention also relates to a method of filling such a column tube with separation medium.
In order for a chromatographic column to be able to separate biological substances effectively, it is usual to pack fine particles of separation material as tightly and as uniformly as possible in the column tube. Filling of the column, or column packing as it is often referred to, is normally effected by closing one end of the column with an outlet means which includes a filter element, and pumping a liquid suspension of the particles under pressure into the other end of the column. Whereas the pumped liquid is able to pass through the filter element essentially unobstructed, the particles are retained by the filter element, so as to build up a particle bed along the length of the tube. As the column tube is filled, the particles are pressed out towards the wall of the tube and the particle bed obtains a stable compaction state with the particles well distributed, this state being maintained during the whole of the filling process.
However, when the column tube has been filled with particles and pumping of the liquid suspension is terminated to enable an inlet element to be fitted to the filling-end of the tube, the stable restraining force in the particle bed is partially lost, resulting in expansion of the particle bed. Consequently, when the column tube is once again placed under pressure, disturbing heterogeneities or irregularities are liable to occur in the particle bed, such as the formation of channels and dead volumes.
Numerous attempts have been made to solve this problem. For instance, EP-A-0040663 suggests that the inlet element is provided with a spring construction which will maintain the column bed under pressure and therewith improve bed stability. A similar construction based on the effect produced by a pressure plunger is described in DE-A-3021366 and U.S. Pat. No. 4,350,595. DE-A-3000475 describes a column having a flexible wall which stabilizes packing of the particles by radial compression of the column packing. A column-filling device including a pressure plunger which functions to compress the bed during the actual filling process but which is then removed is described in U.S. Pat No. 4,549,584. The construction that, at present, has been best established commercially for improving bed stability is one in which the inlet element is provided with a hand-adjustable plunger arrangement or the like, for instance as described in U.S. Pat. No. 4,737,292. A slightly different concept is proposed in U.S. Pat. No. 4,732,687, which describes the use of a perforated plate which is mounted in the upper part of the column and through which a particle slurry can be introduced but which is intended essentially to prevent expansion of one particle bed when the filling device is removed. Further variants are described in JP-A-4-98156, JP-A-2-134562 and GB-A-2,238,257.
All of these earlier proposed solutions involve complicated technical constructions and/or only provide partial compensation for the resultant stability without being able to re-establish the original degree of compaction and density of the packed particle bed.
Accordingly, an object of the present invention is to provide a column having an inlet part which, while being structurally simple, enables the original compactness/density of the particle bed to be maintained, so as to avoid completely those problems that are associated with a drop in pressure in the column bed and expansion of the column bed subsequent to filling the column. Another object of the invention is to provide a method for filling a column in accordance with this concept.
These and other objects of the invention and advantages afforded thereby, as made apparent in the following description, are achieved with a method and a column arrangement having the characteristic features set forth in respective claim
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Hellstrom Karl-Gunnar
Karlsson Kjell
Pharmacia Biotech AB
Therkorn Ernest G.
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