Gas separation: processes – With control responsive to sensed condition – Concentration sensed
Patent
1998-06-12
1999-12-28
Therkorn, Ernest G.
Gas separation: processes
With control responsive to sensed condition
Concentration sensed
95 86, 95 87, 96102, 96104, 96105, 210656, 2101982, B01D 1508
Patent
active
06007602&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the field of chemical separation, particularly gas chromatography.
BACKGROUND OF THE INVENTION
Prior art devices have used moving retention alteration means, such as a moving heater, to form a chemical substance into a single chemical pulse within a tube. Such apparatus is described by DeFord in U.S. Pat. Nos. 3,043,127 and 3,057,183. Many devices employing moving members for injecting substances onto chromatographic columns are known. All such devices form chemical substances into substantially a single chemical pulse so long as deleterious chromatographic practices resulting in accidental peak splitting are avoided. These prior art devices suffer a disadvantage in that a substance is formed only into a single chemical pulse in a tube.
Another class of prior art devices is the comprehensive multidimensional gas chromatograph of Phillips and Liu. described in U.S. Pat. Nos. 5,196,039 and 5,135,549. These devices suffer a disadvantage in that resistive heaters used to form substances into multiple chemical pulses in a tube have shown a tendency to burn out in practice, and to present difficulties with manufacture.
The present invention solves the aforementioned problems.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a method of chemical modulation.
It is an object of this invention :o provide an apparatus for chemical modulation.
It is an object of this invention to improve the reliability of multidimensional gas chromatographs.
It is an object of this invention to establish a technical basis for miniaturizing a comprehensive multidimensional gas chromatograph.
It is an object of this invention to simplify the use of a comprehensive multidimensional gas chromatograph.
It is an object of this invention to provide a dimensional gas chromatograph comprising a cartridge structure.
In accordance with these and other purposes of the invention, a method of chemical modulation is provided whereby a retention alteration means is moved relative to a modulator tube.
Furthermore, apparatus is provided, comprising a retention alteration means, moving means, and a modulator tube, said apparatus providing a chemical modulation.
The present invention will be better understood with reference to several terms, exemplary non-limiting definitions of which, in the context of this application, are set forth below:
A "column" is a device for containing a fluid stream and which provides a chemical separation of retainable substances, e.g., a gas chromatographic column or a capillary electrophoresis tube or other tube.
"Fluid stream" is a directional transport of a gas, liquid, or supercritical fluid. A fluid stream through a chemical separation column has a flow which is considered to move in a downstream direction. An "Upstream" direction is a direction against the fluid stream flow direction.
"Tube" represents a device such as a channel capable of carrying a fluid stream. A tube may have an arbitrary cross section. A rectangular channel etched into the surface of a silicone wafer would be a "tube" in this context. A tube could also comprise multiple separate lengths of tubing or column linked together to form a single tube.
"Chemical flux" is the number of molecules of a substance passing through a cross section of a tube in a given time interval. Its units are area/time, in accordance with the general scientific meaning of the term flux. It is clear that the flux of a substance in a flowing stream may vary with time, and that a graph of such variation could be treated as a time-domain signal. It is also clear that if the concentration of chemical substance varies as a function of position within a tube, the flux would also vary as a function of the position of the cross section To which flux is referred. Hence, flux may vary with position in a tube. Flow velocity couples temporal and positional dependencies of a flux.
"Chemical pulse" is a variation of a chemical flux having a single maximum in time or position.
"Chemical modulation" is a met
REFERENCES:
patent: 3043127 (1962-07-01), Ford
patent: 3057183 (1962-10-01), Ford
patent: 5135549 (1992-08-01), Phillips
patent: 5196039 (1993-03-01), Phillips
Ledford, Jr. Edward B.
Phillips John B.
Board of Trustees of Southern Illinois University on Behalf of S
Therkorn Ernest G.
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