Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Patent
1981-07-15
1986-05-27
Hess, Bruce H.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
2101982, 2101983, 210656, 210658, 428136, 428137, 428138, 428157, 428173, 428192, 428194, 428200, 428210, 428325, B32B 302, B32B 330, G01N 3108
Patent
active
045915245
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a specially prepared chromatographic sheet with adsorbent layer favorably used in pressurized layer chromatographic apparatuses, for the development of linear chromatograms.
Layer chromatography, which is liquid chromatography in a planar arrangement, is a method whereby a mobile phase (the solvent composite) travels on the stationary phase (the adsorbent layer) and carries one or several substances at varying speeds. By the layer chromatographic process, chemical compounds are preferentially adsorbed in an increasing molecular weight sequence onto the solid adsorbent material (the stationary phase). This adsorption is made possible by the solvent (the mobile phase) eluting adsorbed materials from the adsorbent. The distribution of the travelling compounds along the path of the solvent allows the separation of the chemical compounds.
One drawback of classical layer chromatography is the long developing time. Another drawback is that, due to the short length of the adsorbent layer, the separation is not perfect and the theoretical number of plates is limited.
Significant progress was made by the development of high-performance thin-layer chromatography (HPTLC) (see A. Zkatkis and R. E. Kaiser: High Performance Thin-Layer Chromatography, Elsevier, 1977), which, contrary to the classical layer chromatography, results in better dissolution in shorter developing times and shorter distances.
However, the most up-to-date technique is the so-called pressurized (sealed) layer chromatography (Hungarian Patent No. 173,749) which is realizable equally well on thin and thick layers, and provides the fastest separation. The essential step in the technique of pressurized layer chromatography is the application of an overpressure in a closed system to achieve a flow velocity of the solvent (mobile phase) over the adsorbent layer (stationary phase). The adsorbent layer is completely covered suitably with elastic foil, which is pressed in a cushion-like manner against the adsorbent layer by the application of external pressure. The cushion pressure (2-10 bar) should always be higher than the flow pressure (1-8 bar) of the solvent composite. In this so-called pressurized ultramicron chamber a separation can be attained within a very short time (1-10 minutes) which is better than that attainable in the earlier known chromatographic methods utilizing a planar arrangement. An apparatus was constructed for the development of both the concentric and linear chromatograms.
However, the following fundamental problems exist in the linear alternative of the pressurized layer chromatography as a result of the overpressure: (1) the solvent composite escapes at the edges of the adsorbent layer and (2) the front of the solvent flow is not straight, but rather is concentric, semicircular, or arc-shaped following solvent admission, e.g., in case of solvent admission at one point.
SUMMARY OF THE INVENTION
In working out the invention, the aim was to develop a chromatographic sheet with adsorbent layer (stationary phase) applicable in the pressurized layer chromatographic apparatus, which would eliminate the escape of the flowing solvent composite (mobile phase) at the edges of the adsorbent layer, and on which the solvent composite would travel with a straight front.
The invention is based on the recognition that if the adsorbent layer is suitably sealed at its edges, then the solvent cannot escape when overpressure is applied.
Furthermore, the invention is based on the recognition that if the adsorbent layer at and/or near the place of solvent admission is removed from the carrier plate in one or several thin zones, or a thin baffle plate(s) or wire(s) is placed directly in front of the place of solvent admission, i.e., if a minisolvent composite chamber is formed, then the solvent composite will migrate with straight-line front.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the present invention are described with reference to the following figures:
FIG. 1 is a sc
REFERENCES:
patent: 3878100 (1975-04-01), Bixler
patent: 4126554 (1978-11-01), Rainin
Kalasz Huba
Knoll Jozsef
Lak Istvan
Mincsovics Emil
Nagy Janos
Handal Anthony H.
Hess Bruce H.
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