Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2000-03-02
2003-05-20
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S656000, C210S657000, C210S660000, C210S774000, C210S175000, C210S198200, C210S263000, C436S177000, C436S178000, C436S180000, C436S161000, C422S063000, C422S070000, C422S105000
Reexamination Certificate
active
06565752
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a new separation method and a device therefor. The invention is especially related to a method and a device for the separation of different components or species in a given sample for the purpose of their identification, wherein each different species has a specific and different residence time in a separation channel or is irreversibly retained at a specific and different position in said channel.
BACKGROUND OF THE INVENTION
In chromatographic chemical analysis methods, a sample containing one or more unknown components (sample species) is contacted with a carrier fluid (usually referred to as the mobile phase) which carries the sample solutes through a separation channel (or column) in which a retentive layer (usually referred to as the stationary phase) is arranged. During their motion through the separation channel, the sample species are continuously exchanged between the retentive layer and the mobile phase (the mobile phase is usually selected such that it has no or only a small affinity for the retentive phase). As the different sample species have a different affinity for the retentive layer, one species will spent more time in the retentive layer than another. As a consequence, all different species will move through the separation-channel with a different velocity. Arranging a detector device at the end of the separation channel, the different sample species will pass the detection point in a clearly separated mode. The response signal which is obtained when each ensemble of identical sample species passes the detector is commonly referred to as a peak.
To obtain an optimal performance, the width (i.e., in the time domain) of this peak should be as small as possible compared to the mean channel residence time of the given ensemble of sample species.
Presently, the two most popular chromatographic techniques are either pressure-driven or electrically driven. In pressure-driven chromatography, the mobile phase motion is generated by applying a pressure difference across the separation channel. The two most popular versions of pressure-driven chromatography are packed-column liquid chromatography (HPLC) and open-tubular gas chromatography (capillary GC), which are characterized in that different sample species have a different and unique residence time in the separation channel, and which are also characterized in that all sample species are detected only once. These two chromatographic techniques suffer from the fact that the pressure drop may not exceed a given value. As can be learned from Poiseuille's law, this pressure-drop limitation restricts the allowable column length and the applicable mobile phase velocity. Poiseuille's law also shows that the pressure drop limitation also puts a down limit on the effective column diameter d (open-tubular columns) or particle diameter d
p
(packed columns) which can be used when a given separation quality has to be achieved. The latter restriction puts a second down-limit on the analysis time, because the analysis time can be considered to be proportional to d
2
or d
P
2
. In electrically driven separations, a similar down-limit on the analysis time exists. In this case, the down-limit originates from the existence of a maximal allowable voltage drop.
The documents U.S. Pat. No. 4,874,507 and DE 41 08 820 describe continuous separation devices in which two oppositely moving surfaces are used to transport electrically charged or absorbed solid particles or fluid substances in two different directions. These devices and methods only enable to divide a liquid or solid feed stream into two different fractions. A complete single step fractionation is impossible, nor is it possible to characterize the nature of the different sample components from their unique and different residence time in the channel, as is possible with the methods known to those skilled in the art of HPLC or capillary GC.
In patent application EP 0 670 489 (Manz, 1997) a closed annular separating device is presented in which the use of a freely rotating internal toroidal ring is proposed as one of the possibilities to recirculate (i.e., without creating any net fluid displacement) the mobile phase in a closed channel.
The fact that a closed (annular) envelope is needed to cope with the pressure build-up inside the device restricts the field of application to batch mode separations (i.e., no inflow of fresh eluting mobile phase fluid during the actual separation). The device and method in EP 0 670 489 is hence not related to the type of once-through analytical separations known to those skilled in the art of HPLC or capillary GC. The device and method in EP 0 670 489 generates a complex system of continuously revolving and overtaking substance peaks, potentially causing undesirable competitive adsorption effects when two already separated substance peaks overtake each other. Furthermore, when the sample contains a large number of different species, inextricable chromatograms are obtained. In contrast thereto, it is a main objective of the present invention to provide a pressure-drop less operation of the type once-through analytical separation methods known to those skilled in the art of HPLC or capillary GC, characterized in that different sample species have a different and unique residence time in the separation channel, and which are also characterized in that all sample species are detected only once.
BRIEF DESCRIPTION OF THE INVENTION
In the method according to the present invention, the separation occurs in a separation channel, said channel being defined by at least two channel elements, and said channel being substantially sealed along its mantle surface, characterized in that the movement of the mobile phase in, through and out the separation channel is mainly caused by a relative axial movement of at least one of the channel elements compared to at least one of the other channel elements. In the present text, the notion “moving channel element” is used to refer either to a movable part of the channel wall or to a movable mechanical device positioned in the channel's interior.
In the device according to the invention the thickness of the channel is between 0.01 micron and 100 micron and preferably between 0.1 and 10 micron, and the width of the channel is between 0.1 micron and 10 centimeter and preferably between 10 and 1000 micron.
The methods according to the present invention are based upon the fact that, instead of applying a (pressure) force at the channel inlet only, the motion of the mobile phase fluid is generated by applying a force all along the column length. As a consequence, the mobile phase flow is generated without creating a pressure drop.
In the embodiments according to the present invention, the desired mobile phase flow is at least partly generated by the shear forces which originate from this moving element. In some of the embodiments according to the present invention, the mobile phase flow is furthermore sustained by one or more relief elements, such as one or more protrusions, recesses, holes or irregular porous-like structures, which are provided on the surface of the moving elements.
This implies that in all the embodiments according to the present invention, the mobile phase motion is generated without creating a pressure drop; and hence without the need to impose an excess pressure at the channel inlet, which pressure differences are considered as a basis for potential separation and identification problems. This explains why the moving channel element can also be apart of the channel wall, because, as the pressure inside the channel is substantially identical along its entire length, this pressure can be kept substantially equal to the pressure outside the channel such that the sealing of a channel mantle which consists of two independently movable wall elements poses no specific problem.
To obtain a suitable operation of the method and the device according to the present invention, any specific affinity between the surface of the moving channel elem
Baron Gino
Desmet Gert
Banner & Witcoff , Ltd.
Drodge Joseph W.
Vrije Universiteit Brussel
LandOfFree
Method for separating a fluid substance and device therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for separating a fluid substance and device therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for separating a fluid substance and device therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3093921