Liquid purification or separation – With means to add treating material – Chromatography
Patent
1981-11-02
1984-01-03
Adee, John
Liquid purification or separation
With means to add treating material
Chromatography
55386, B01D 1508
Patent
active
044241275
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a column for performing liquid and gas chromatography, particularly the latter, comprising a plurality of capillaries coupled in parallel.
Gas chromatography based on the use of single capillaries as a column is often used to a large extent in analytic chemistry. The different advantages and effects which can be obtained by such capillary columns are extensively described in the literature, for example Kaiser, R. E.: Chromatographie in der Gasphase, third ed., Vol. 2, Bibliographisches Institut, Mannheim, 1975; Ettre, L. S.: Open Tubular Columns in Gas Chromatography, Plenum Press, New York, 1965.
The primary advantage of using a capillary column is the good separation effect that can be obtained. Thus, it is generally known that the smaller the interior diameter of the column the better the dissolution, i.e. the separation of the components of the gas mixture. However, capillary columns are subject to the obvious disadvantage that their capacity is strongly delimited, which necessitates the use of particular sample injecting devices and very sensitive detectors.
The use of several capillary columns with as identical properties as possible and coupled in parallel could result in elimination of the disadvantage residing in the limited capacity of the capillary column. By using a larger number of capillary columns coupled in parallel it would thus be possible to separate and prepare substances in a pure form in larger quantities while maintaining the ability of the single capillary column of chromatographic dissolution.
However, hitherto proposed multicapillary column constructions have not been found to be practically useful, mainly in view of the fact that it has been found to be difficult to provide for a column composed of several capillaries coupled in parallel wherein in practical operation the individual capillaries show a somewhat identically similar behaviour. The differences that may arise between the individual capillaries in the composite column can consist in deformation of the capillaries in different degrees depending on the position in the column structure, arising temperature gradients over the cross section of the column, etc. The first one of said differences between the individual capillaries in the column can be wholly devastating for the operational characteristic in view of the fact that the linear flow through a capillary tube is proportional to the fourth power of the inner diameter of the tube in accordance with Poiseuille's equation: (modified)
For longer tubes having a greater pressure drop also the compressibility of the gas must be introduced as a factor but this does not change the dependence of the gas flow of the fourth power of the diameter.
Another essential disadvantage of proposed constructions based on the multi-capillary column is the relatively large thermal mass of the column, whereby it is not possible rapidly to change the temperature of the column without causing radial temperature gradients which result in different separation rates of the different capillaries which results in loss of the dissolution ability of the multicolumn.
The present invention has for its purpose to provide a column for carrying out gas chromatography and wholly or partly avoiding the above disadvantages. For this object the invention provides for a column wherein the capillaries are arranged side by side or woven or pleated together in the form of a flat band-like device. By arranging the column in this manner the essential advantages are obtained residing in the fact that the column can be bent and rolled up without resulting tensions and deformations in same.
In its simplest form the column according to the present invention consists of capillaries arranged side by side, the capillaries preferably in some suitable manner being held together mechanically, at least laterally. The simplest way of keeping the capillaries together consists in baking same into some suitable binding material, for example a hardenable plastic.
In an alternative embodiment of the
REFERENCES:
patent: 3442002 (1969-05-01), Geary, Jr. et al.
patent: 3570673 (1971-03-01), Dutz et al.
patent: 4031012 (1977-06-01), Gics
patent: 4293415 (1981-10-01), Bente et al.
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