Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
  • B01D15/08—Selective adsorption, e.g. chromatography
  • B01D15/10—Selective adsorption, e.g. chromatography characterised by constructional or operational features
  • B01D15/22—Selective adsorption, e.g. chromatography characterised by constructional or operational features relating to the construction of the column
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/50—Conditioning of the sorbent material or stationary liquid
  • G01N30/52—Physical parameters
  • G01N2030/524—Physical parameters structural properties
  • G01N2030/527—Physical parameters structural properties sorbent material in form of a membrane
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
  • G01N2030/8881—Modular construction, specially adapted therefor
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/60—Construction of the column
  • G01N30/6004—Construction of the column end pieces
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/60—Construction of the column
  • G01N30/6004—Construction of the column end pieces
  • G01N30/6017—Fluid distributors
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/60—Construction of the column
  • G01N30/6091—Cartridges

Definitions

• This invention is related to chromatography devices, porous medium modules used in chromatography devices and methods for making porous medium modules, including a porous medium module having a stack of porous media, such as porous membranes or sheets.
• Chromatography is a term applied to a variety of separation techniques and can be classified in several ways, including gas chromatography and liquid chromatography, such as ion exchange chromatography, affinity chromatography, size exclusion chromatography, etc.
• chromatography as used herein includes any conventional chromatographic and/or adsorptive separation technique.
• a chromatography process may be illustrated using ion exchange chromatography.
• Ion exchange chromatography usually involves a two-step process for separating components from the fluid containing the components. First, a test sample including a fluid and the components contained therein is passed through a chromatography device such as a chromatography column.
• the chromatography device usually includes a stationary separation medium, such as a bed of porous beads or a stack of porous membranes or sheets, for separating or isolating the components from the fluid.
• a stationary separation medium such as a bed of porous beads or a stack of porous membranes or sheets, for separating or isolating the components from the fluid.
• the components become associated with the separation medium by any of a variety of chemical and/or physical processes. For example, the components may become chemically or physically attached to the separation medium.
• the components may be attached to the medium by electric charge.
• a continuous stream of an eluent is passed through the separation medium, whereupon the components attached to the separation medium are released to the eluent.
• the eluent may be a salt solution, ions of which replace the components on the separation medium.
• the salt concentration is varied with time either gradually using gradient elution or suddenly as in step or isochratic elution. Because different components have different affinities for the separation medium, the time at which each component is released into the eluent may vary.
• each component in the eluent is .generally detected by measuring changes in the physiochemical properties (for example, by measuring the adsorption of light at 280 nm) of the eluent as the eluent exits the separation medium. A plot of the changes of these properties versus time will exhibit response peaks corresponding to the presence of the components contained in the eluent. Whether a component is contained in the test sample may be determined by examining the existence of the corresponding peak.
• the peaks be well separated.
• the peaks be narrow.
• the response peaks in the plot are narrow and well separated.
• the flow of the fluid, such as the test sample and/or the eluent, through the separation medium is uniform.
• Uniform fluid flow through a separation medium may be characterized by such parameters as uniform flow rate per unit area across the entire flow area and uniform residence time for fluid traversing each streamline of the flow. Residence time is defined as the time during which a fluid particle is within the chromatography device as a whole or within one or more parts of the chromatography device, such as the separation medium.
• the flow of the test sample is non- uniform.
• the test sample entering the separation medium may not be uniformly distributed across the entire flow area and "channeling" may occur as a result.
• Channeling is a phenomenon where certain areas of the fluid front of the test sample have a higher flow rate than other areas of the fluid front.
• the portions of the separation medium experiencing higher flow rates may encounter greater quantities of the components and may become saturated before other portions of the separation medium. This may cause the component to "break through” to the outlet of the device before the entire medium is saturated, thus reducing the total quantity of the component that may be captured before some is lost at the outlet.
• the non-uniform flow of an eluent may cause a component to appear sooner in a portion of the eluent having a higher flow rate and later in a portion of the eluent having a lower flow rate. Even if the eluent has uniform flow rates, non-uniform residence times may cause the component to appear sooner in a portion of the eluent having a shorter residence time and later in a portion of the eluent having a longer residence time. These phenomena may cause the component to appear in the different streamlines of the eluent at different times.
• non-uniform flow may cause the component to appear in a longer segment of the eluent flow stream at a lower concentration, making the response peaks wider and less concentrated. Wider and less concentrated response peaks may lead to an overlapping of the response peaks, making the identification of the response peaks, and consequently the identification and separation of the corresponding components, more difficult.
• This invention provides porous medium modules and methods for making porous medium modules, which overcome many of the drawbacks of the prior art, including the problems discussed above.
• a porous medium module for use in adsorptive and/or chromatographic separations includes a hollow housing member, a plurality of porous media stacked in the hollow housing member, and a sealant disposed between the stacked porous media and the hollow housing member and sealing an outer periphery of the stacked porous media.
• a porous medium module for use in adsorptive and/or chromatographic separations includes a plurality of stacked porous media having an outer periphery, and a sealant disposed around the outer periphery of the stacked porous media.
• the sealant penetrates into the outer periphery of the stacked porous media, and the depth of penetration of the sealant into the outer periphery of the stacked porous media is substantially uniform.
• a porous medium module for use in adsorptive and/or chromatographic separations includes a hollow housing member having an inner surface, a plurality of porous media stacked in the hollow housing member, and a sealant disposed between the stacked porous media and the hollow housing member, wherein the housing member includes a configuration that interlocks the housing member and the sealant.
• a porous medium module for use in adsorptive and/or chromatographic separations comprises a hollow housing member, a plurality of porous media stacked in the hollow housing member, and a mechanism operatively associated with the hollow housing member and the stack of porous media, wherein the mechanism centers the stack of porous media in the hollow housing member.
• a porous medium module for use in adsorptive and/or chromatographic separations comprises a plurality of stacked porous media having an outer periphery, at least one porous medium support having an outer peripheral region, the porous medium support being operatively associated with the stacked porous media, and a sealant disposed around the stacked porous media and the porous medium support.
• the sealant penetrates into the outer periphery of the stacked porous media and into the outer periphery of the porous medium support, and at least a portion of the outer peripheral region of the porous medium support is at least partially obstructed to reduce the penetration of the sealant into the porous medium support.
• a porous medium module for use in adsorptive and/or chromatographic separations comprises first and second permeable porous medium supports, a plurality of porous media stacked and compressed between the first and second permeable porous medium supports, and a hollow peripheral arrangement disposed around the supports and the media and coupled to the edges of the supports and media to seal and support the supports and media.
• a porous medium module for use in adsorptive and/or chromatographic separations includes first and second porous medium supports, a plurality of porous media stacked between the first and second permeable porous medium supports, and a sealant coupled to the porous medium supports to secure the porous medium supports to the porous media.
• a porous medium module for use in separations comprises a plurality of stacked porous media having an outer periphery and a first end, and a sealant disposed around the outer periphery of the stacked porous media, the sealant forming at least a portion of a first seal gland near the first end of the stack.
• a porous medium module for use in separation comprises a plurality of stacked porous media having an outer periphery and a first end, and a sealant disposed around the outer periphery of the stacked porous media, the sealant forming a first seat arrangement near the first end of the stack.
• a method for making a porous medium module comprises stacking a plurality of porous media, disposing a liquid sealant around the outer periphery of the stack of porous media, allowing the sealant to penetrate into the outer periphery of the stack of porous media, and allowing the liquid sealant to solidify to form a seal around the stacked porous media.
• Porous medium modules embodying various aspects of the present invention have a number of advantages over the prior art.
• the porous medium modules may provide a strong, effective seal for the stacked porous media.
• the sealant preferably contacts and/or penetrates the outer periphery of the porous media, forming a strong, effective seal around the porous media and preventing leakage around and laterally through the outer periphery of the stacked porous media.
• porous medium modules may minimize stagnant flow areas in the flow path.
• the sealant of the porous medium module may be arranged to penetrate evenly and uniformly into the stack of porous media, minimizing the formation of crannies and crevices.
• the porous medium modules preferably do not use any mechanical sealing devices, such as O-ring seals or gaskets, or any mechanical fastening means, such as bolts, to seal and secure the stacked porous media within the module, thus minimizing the formation of stagnant flow areas.
• the porous medium modules may include porous media in a compressed state, which offers a number of advantages. For example, compressing the porous media reduces the possibility of non-homogenous packing.
• the porous media preferably are compressed uniformly before they are sealed within the porous medium module, ensuring homogenous packing.
• the bonding and sealing process generally involves the use of O-ring seals or gaskets to seal the porous media and the use of bolts to secure the stack of porous media.
• the use of O-ring seals, gaskets or bolts generally involves the compression of only a portion of the porous media, causing non-homogenous packing.
• An additional advantage of compressing the porous media is that it reduces the gap between adjacent porous media, preventing the sealant from penetrating much further between adjacent porous media layers than it does edgewise into the outer periphery of each media layer. This minimizes the formation of crannies and crevices in the flow path and consequently the formation of stagnant flow areas.
• a further advantage of compressing the porous media is that the porous medium module may have a more consistent separation performance.
• An important parameter affecting the separation performance of a porous medium module is the height of the porous media. Compression of the porous media may allow a more precise control of the height of the porous media and consequently a more consistent separation performance for the porous medium module.
• Figure 1 is a sectional view of one embodiment of a chromatography device.
• Figure 2 is a sectional view of one embodiment of a porous medium module.
• Figure 3 is a sectional view of another embodiment of a porous medium module, illustrating the penetration of sealant into the porous media.
• Figure 4 is a sectional view of another embodiment of a porous medium module, illustrating the penetration of sealant into the porous media and the porous medium supports.
• Figure 5 is a sectional view of another embodiment of a chromatography device.
• Figure 6 is a sectional view of the porous medium module used in the embodiment shown in Figure 5.
• Figure 7 is a partial sectional view of the porous medium module used in the embodiment shown in Figures 5 and 6, showing sealant penetration into the porous membranes and porous medium supports.
• Figure 8 is a partial sectional view of the porous medium module used in the embodiment shown in Figures 5 and 6, showing a housing member with beveled ends.
• Figure 9 is a top view of the porous medium module used in the embodiment shown in Figure 5, showing spacers disposed between the housing member and the stack of porous membranes and porous medium supports.
• Figure 10 is a partial sectional view of the porous medium module used in the embodiment shown in Figures 5 and 6, showing a ring seal seated on the sealant.
• Figure 11 is a partial sectional view of another embodiment of a device.
• FIG. 1 illustrates one example of a chromatography device 10 embodying the invention.
• the chromatography device 10 may include an inlet 12, an outlet 14, a porous medium module 20 and a porous medium module holder 40 holding the porous medium module 20.
• the porous medium module holder 40 and/or the porous medium module 20 may define a flow path providing fluid communication between the inlet 12 and the outlet 14.
• the porous medium module 20 may be disposed in the flow path and may include a single porous medium or a plurality of porous media 22.
• a fluid such as a test sample or an eluent, may enter the chromatography device 10 through the inlet 12, pass through the porous medium module 20 and exit the chromatography device 10 through the outlet 14.
• a chromatography device may include only one porous medium module 20, as shown in Figure 1, or it may include a plurality of porous medium modules disposed in one or more porous medium module holders.
• the plurality of porous medium modules may be arranged within a porous medium module holder in various parallel, series, or series/parallel arrangements.
• a chromatography device can include multiple inlets and multiple outlets, and each inlet or outlet may serve one or more porous medium modules.
• a wide variety of porous medium module holders may be used with the porous medium module.
• the porous medium module holder 40 preferably includes two holder sections such as opposed plates 42, 44 between which the porous medium module 20 may be disposed.
• Connectors such as a plurality of bolts 46 or clamps, may secure the porous medium module 20 between the two plates 42, 44.
• the inlet 12 and outlet 14 may be respectively placed near the centers of the two plates 42, 44, and each of the inlet 12 and outlet 14 may include a female threaded socket intended to receive a male threaded fitting with substantially the same inner diameter as the passage 16, 18.
• a first flow distributor arrangement 52 may be disposed in the flow path between the inlet 12 and the porous medium module 20 and/or a second flow distributor arrangement 54 may be disposed in the flow path between the porous medium module 20 and the outlet 14.
• Each flow distributor arrangement 52, 54 may include a tapered space 60, 62 and one or more porous fluid distributors 30, 32, 56, 58 operatively associated with the tapered space 60, 62.
• a flow distributor arrangement 52 may include a tapered space 60 and two flow distributors 30, 56.
• the flow distributor arrangement 52 may include only one of the two distributors 30, 56.
• Each of the tapered spaces may be substantially free of structures, e.g., completely free of structures.
• one or both of the tapered spaces may include structures, such as support structures and/or flow channels.
• the first flow distributor arrangement 52 may be disposed between the inlet fluid passage 16 and the porous medium module 20 facing the inlet fluid passage 16.
• the second flow distributor arrangement 54 may be disposed between the outlet fluid passage 18 and the end of the porous medium module 20 facing the outlet fluid passage 18.
• the porous medium module holder may have any suitable configuration.
• the porous medium module holder may have a hollow, cylindrical configuration or a configuration similar to that of a container.
• the inlet and outlet may be placed at any suitable locations, as long as they allow a test sample or an eluent to enter and exit the chromatography device 10, respectively.
• the porous medium module holder may include a key mechanism that ensures that the porous medium module holder and the porous medium module are properly aligned when the porous medium module is disposed in the porous medium module holder.
• each of the plates 42, 44 of the module holder 40 is sealed to the end of the porous medium module 20 to prevent radially outward leakage through the gap between the plate 42, 44 and the end of the porous medium module 20.
• the seal is arranged to prevent the creation of any stagnant flow areas. Fluid flowing into and out of any stagnant areas may create non-uniform flow rates and residence times.
• the seal can be provided in a variety of ways.
• seals such as ring seals or annular gaskets
• the seals may be integral or unitary with the sealant 24 of the porous medium module 20.
• the plates 42, 44 or the porous medium module 20, or both, may have an annular groove to accommodate each seal 48, 49.
• the inner diameter of each seal 48, 49 preferably is substantially the same as the diameter of the flow path through the porous medium module 20.
• the seal when each seal is compressed into an annular groove, the seal preferably seals the opening of the groove from the fluid so that the fluid does not flow into the groove, preventing the formation of stagnant flow areas in the groove.
• each seal 48, 49 has a generally rectangular (or trapezoidal) cross-section
• the groove has a generally rectangular (or trapezoidal) cross-section.
• the seal 48, 49 and groove are so dimensioned that, when the seal is compressed into the groove, the opening of the groove is substantially sealed by the seal 48, 49.
• an exemplary embodiment of the porous medium module 20 of the present invention may include a plurality of stacked porous media 22 and a sealant 24 disposed around the periphery of the stacked porous media 22.
• the sealant 24 may penetrate into the outer periphery of the stacked porous media 22 to form a strong, effective seal.
• the sealant 24 may penetrate far less, or may not significantly penetrate into the outer periphery of the stacked porous media 22 but may contact the outer periphery to form a strong, effective seal.
• the porous medium module 20 may also include a hollow housing member 26, and the sealant 24 may be disposed between the stacked porous media 22 and the hollow housing member 26.
• the porous medium module 20 may also include first and/or second porous media supports 30, 32, which is operatively associated with the stack of porous media 22.
• first and/or second porous media supports 30, 32 may be disposed respectively at the ends of the stack of porous media 22.
• the stacked porous media may have any suitable configuration, depending on the desired configuration of the chromatography device. In the embodiment shown in Figures 1 and 2, the stack of porous media 22 has a substantially cylindrical configuration having a generally circular cross section. Alternatively, the stack of porous media may have, for example, a square, rectangular or polygonal cross section.
• the stacked porous media 22 may include any desired number of layers of porous media 22, depending on the specific application.
• the number of layers of porous media may be selected according to any suitable criterion. For example, it may be desirable to select the number of layers by establishing a maximum pressure drop for a desired axial flow rate through the porous medium module.
• the stack of porous media 22 may include from about 2 or fewer to about 125 or more layers, preferably from about 65 to about 100 layers, more preferably from about 70 to about 100 layers, e.g., about 95 layers, of axially stacked porous media.
• the stack of porous media may include from about 5 to about 50 layers, preferably from about 10-30 layers, e.g., 16 layers, of axially stacked porous media.
• the number of layers of porous media 22 may also be selected to obtain a desired compression ratio for a given pre-compression height of the porous media 22.
• Compression ratio is defined as the ratio of the post-compression height of the porous media over the pre-compression height of the porous media.
• porous media including any porous medium suitable for use in membrane chromatography, may be utilized in the porous medium module.
• the porous medium may have any suitable structure and may be formed from any suitable type of material.
• the porous medium may include a porous substrate formed from an inorganic material, such as a metal or a ceramic, including glass, or the porous medium may include a natural or synthetic polymer, such as poly ether sulfone, polysulfone, polyvinylidene fluoride, polyester, nylon or cellulose.
• the substrate may be, for example, a porous sheet of sintered or resin-bonded inorganic particles or fibers, a woven or non- woven sheet of polymeric fibers, or a porous polymeric film or membrane.
• the substrate may be naturally useful as a chromatography medium or it may be modified physically and/or chemically to be more useful as a chromatography medium.
• the substrate may be charge-modified to provide a positive or negative charge, or it may be coated or surface-modified to provide one or more interactive substances, such as affinity ligands, antibodies, and antigens.
• the porous substrate may be impregnated with various substances, such as porous resins, useful in chromatography.
• Each porous medium may include one or more layers and may be supported or unsupported.
• the porous medium may comprise an externally or internally supported polymeric membrane.
• suitable porous media may have a variety of pore structures, permeabilities, and dimensions.
• the porous medium may have a uniform pore structure or a non-uniform pore structure, such as a graded pore structure or an asymmetrical pore structure.
• the porous medium may have a removal rating in the range from about 0.2 ⁇ or less to about 5.0 ⁇ or more, more preferably in the range from about 0.3 ⁇ to about 1.5 ⁇ .
• the thickness of each porous medium may be in the range from about 0.001 inch or less to about 0.5 inch or more.
• the thickness is less than about 0.010 inch and more preferably in the range from about 0.002 inch to about 0.008 inch, for example, from about 0.003 inch to about 0.007 inch.
• the membrane layers are preferably each of uniform thickness across their flow area, preferably within about +/-20% of the nominal thickness of the membranes, more preferably within about +/-10% of the nominal thickness.
• the lateral dimension(s), e.g., the diameter may be as large as may be practically manufactured, for example, up to about 1 meter or more. In the embodiment shown in Figure 1, the diameter of the membrane is preferably about 40 cm or less, e.g., about 15 cm or less.
• the porous media 22 are preferably stacked one on another, as shown, for example, in Figure 3.
• each porous medium may be identical or different. Where the opposing surfaces are different, adjacent media may be stacked on one another with similar surfaces facing one another or dissimilar surfaces facing one another.
• a porous medium may have a "shiny" side (i.e. , a smooth side) and a "dull” side (i.e., a rougher side).
• the roughness of the "shiny” surface is on the order of the pore size of the porous medium.
• a sealant 24 is preferably disposed around and preferably seals the outer periphery of the stack of porous media 22.
• the sealant 24 may have any configuration that effectively seals the porous media 22, depending on the configuration of the porous media 22.
• the sealant 24 has a hollow cylindrical configuration and is disposed around the cylindrical side surface of the stack of porous media 22.
• the sealant 24 may also serve to support the stack of porous media 22 at the outer periphery.
• the sealant 24 may comprise any suitable material which will seal and/or bond to the outer periphery of the stack of porous media 22.
• a suitable material is a thermoplastic material such as a polyethylene, polyolefin, or polypropylene. Thermoplastic materials may be particularly useful if the sealant is to be injection molded around the stack of porous media.
• Another example of a suitable material is material which may be applied around the stack of porous media as a liquid and then cured or hardened to form a seal and/ or bond.
• a curable material is a thermosetting material such as an epoxy, silicone, or curable polyurethane.
• a preferred thermosetting material is a bi-component polyurethane.
• the sealant 24 may penetrate (1) radially (i.e. , edgewise) into the outer periphery of each porous medium 22 of the stack and/or (2) radially between adjacent porous media 22 of the stack to form a strong, effective seal and to ensure that the sealant 24 is securely bonded to the porous media 22.
• This can be done, for example, by applying the sealant as a liquid around the stack of porous media 22.
• the liquid sealant is then allowed to penetrate a short distance radially into the outer peripheries of the porous media, filling the interstices in the porous media 22 at the outer periphery, and to penetrate a short distance radially into gaps between the layers of porous media 22.
• the sealant 24 may penetrate into and between the porous media 22 to define an inwardly facing side surface of the sealant 24 which is positioned radially inwardly from the outwardly facing side surface of the media stack 22.
• the sealant 24 thus prevents leakage radially through and circumferentially around the side surface of the media stack and ensures that the sealant 24 is securely bonded to the porous media 22.
• the depth of the penetration of the sealant 24 into and between the porous media 22 may be controlled to achieve various desired results.
• the sealant 24 preferably penetrates into the porous media 22 sufficiently deep to form a strong, effective seal and/or bond but not so deep as to unduly reduce the effective flow area axially through the stack of porous media 22.
• the depth of penetration into and between the porous media preferably is substantially uniform along the stack of the porous media 22.
• the sealant may penetrate between adjacent porous media layers further than it penetrates edgewise into the outer periphery of each media layer.
• the sealant may penetrate edgewise into the outer periphery of each media layer further than it penetrates between adjacent layers.
• the maximum variation (d) along the stack of porous media may be less than or equal to about 0.010 inch, preferably less than or equal to about 0.005 inch.
• the maximum variation (d) is most preferably less than or about equal to the thickness of the porous medium.
• the pitch of the variation i.e., the axial distance from one peak of penetration to the next adjacent peak of penetration, is most preferably greater than or about equal to d. Limiting the maximum variation in the depth of penetration thus provides a sealant which has an inwardly facing surface that is substantially uniform.
• Chromatography porous medium modules embodying this aspect of the invention are superior to many chromatography devices which have a non-uniform depth of penetration.
• Non-uniform penetration creates crannies, crevices and other areas where fluid flow stagnates. Test samples and eluents flowing through these devices move in and out of these stagnant areas with highly non-uniform flow rates and residence times, broadening response peaks and reducing resolution.
• porous medium modules embodying this aspect of the invention may exhibit far more uniform flow velocities and residence times, sharper peaks, and enhanced resolution.
• the first and second permeable porous medium supports 30, 32 may perform a number of functions.
• porous media 22 may support and protect the axial ends of the stack of porous media 22. They may be used to provide a uniform axial compression to the stack of porous media 22 to prevent the porous media 22 from, for example, bulging at the center of the porous media 22, resulting in a uniformly packed porous media 22.
• the permeable porous medium supports 30, 32 may also serve as flow distributors, directing flow to or from the stack of porous media 22, to provide more uniform flow velocities and residence times.
• the porous medium supports may have any suitable configuration that allows the porous medium supports to perform one or more of the above functions.
• Each porous medium support may be a single layer structure which performs one or more of the above functions or it may comprise a multilayer structure, each layer performing one or more of the above functions.
• Each of the porous medium supports 30, 32 may be identical and may have a shape similar to the shape of a porous medium.
• the lateral dimension(s) of each support member may be similar to those of the porous medium or they may be larger or smaller.
• the porous medium supports may extend beyond the outer periphery of the stack of porous media to the sealant or may extend over or within the sealant, e.g. , to the hollow housing member.
• porous medium supports 30, 32 may have the configuration of a circular disk with a diameter similar to that of the porous media 22.
• each porous medium support may vary along one or both of the lateral dimensions, e.g., the diameter, of the porous medium support.
• the porous medium support may have a configuration with a varying thickness, such as a conical configuration, which may be useful in distributing flow evenly to the stack of porous media.
• the thickness is preferably substantially constant along the lateral dimensions of the porous medium support 30, 32.
• the outer periphery of each porous medium support 30, 32 may be beveled, as shown in Figure 4. The beveled periphery of porous medium supports 30, 32 allows the sealant 34 to be positioned over a portion of each porous medium support 30, 32 to secure the porous medium supports 30, 32 to the stack of porous media 22.
• Each porous medium support may be permeable at least in a region overlying the stack of porous media and may be permeable over substantially the entire area. While the permeability of each porous medium support may vary along one or both lateral dimensions, the permeability is preferably uniform. Further, each porous medium support is preferably much more permeable than the stack of porous media. For example, the porosity of each porous medium support may be much greater than the porosity of each porous medium.
• the removal rating of the porous medium support may be in the range from about 10.0 ⁇ or less to about 50.0 ⁇ or more, preferably in the range from about 20.0 ⁇ to about 50.0 ⁇ , while the removal rating for the porous medium may be in the range from about 0.5 ⁇ or less to about 1.5 ⁇ or more.
• the pressure drop through each porous medium support is preferably much less than the pressure drop through the stack of porous media.
• the pressure drop through each porous medium support may be less than or equal to about 10% of the pressure drop through the stack of porous media, preferably less than or equal to about 1 % of the pressure drop through the stack of porous media.
• the porous medium supports may be fashioned from a wide variety of materials and in a wide variety of ways to support the stack of porous media and/or distribute flow to the porous media.
• the porous medium supports preferably have sufficient structural integrity to evenly support the stack of porous media under compression and more preferably without any billowing of the porous media, thereby providing a media stack having a uniform height between the porous medium supports.
• Materials suitable for the porous medium supports include metals, ceramics, and polymers which are compatible with the test samples and eluents.
• Configurations suitable for the porous medium supports include perforated plates and rigid screens or meshes which may have openings from about 25 microns and or less to about 0.062 inch or more, preferably from about 0.010 to about 0.030 inch.
• Preferred configurations include a rigid porous sheet, supported or unsupported, of bonded or sintered metallic or polymeric particles or fibers.
• One example is a 0.08-inch thick unsupported porous sheet of sintered stainless steel particles.
• the sealant 24 may also penetrate radially (i.e. , edgewise) into the outer periphery of each porous medium support 30, 32 and/or may penetrate radially between each porous medium support 30, 32 and the adjacent porous medium 22.
• the penetration of the sealant 24 into the porous medium supports 30, 32 and between each porous medium support 30, 32 and the adjacent porous medium 22 is similar to the penetration of sealant 24 into the stack of porous media 22, in terms of both the depth of penetration and the variation of penetration, resulting in a sealant which has an inwardly facing surface that may be substantially uniform.
• the depth of penetration into the porous medium supports 30, 32 and between each porous medium support 30, 32 and the adjacent porous medium 22 is substantially equal to or slightly greater than the depth of penetration into the porous media 22 and between the porous media 22.
• the variation of penetration into the porous medium supports and the porous media is also similarly limited to maintain a smooth flow path from one porous medium support through the stack of porous media to the other porous medium support, resulting in a uniform fluid flow through the porous medium module 20.
• each porous medium support 30, 32 may be far more permeable than the porous media 22, at least a portion of the outer periphery of each porous medium support 30, 32 may be treated or otherwise obstructed in any suitable manner to reduce permeability at the outer periphery.
• the reduced permeability limits the depth of penetration of the sealant into the porous medium support 30, 32 so that the penetration of sealant into the porous medium support 30, 32 is substantially the same as, or only somewhat greater than, the penetration of the sealant into the porous media 22.
• at least a portion of the outer periphery of the porous medium supports may be coated or impregnated with any suitable material that limits permeability at the outer periphery.
• each porous medium support may be machined in a manner which reduces its permeability.
• a portion of each porous medium support 30, 32 is beveled in a manner which reduces the permeability at the outer periphery of the porous medium support.
• the bevels 35 may be formed, for example, by laser cutting, water-jet cutting, machine cutting or grinding. In this manner, the pores on the beveled portion 35 of the outer periphery may be completely, substantially or partially obstructed, limiting the depth of penetration of the sealant.
• the bevel 35, or other treatment preferably does not encompass the full outer peripheral surface of a porous medium support, as shown in Figure 4.
• a portion 36 of the side surface of each porous medium support 30, 32 may remain unobstructed or only slightly obstructed, and the size of the unobstructed or only slightly obstructed portion 36 may be selected to control the depth of penetration of the sealant. For example, it may be 60% or less, preferably 35% or less, e.g., 25% , of the thickness of the porous medium support.
• the porous medium module shown in Figure 4 comprises a sealant bonding and sealing a plurality of porous media 22 between opposite porous medium supports 30, 32.
• several layers of identical porous media 22 are the only layers disposed between the opposing porous medium supports 30, 32.
• the stack may be configured in any other suitable manner.
• layers or regions of dissimilar porous media may be disposed in the stack.
• additional structures may be disposed in the stack.
• one or more structural supports, such as the porous medium supports, and/or one or more flow distributors or headers may be disposed at various locations, e.g. , axially spaced locations, within the stack.
• the sealant is preferably disposed around the outer periphery of the stack bonding and sealing the various layers and defining an axial flow path through the porous medium module.
• the hollow housing member 26 principally functions to support the porous medium module 20 against the radially outwardly directed forces of a fluid flowing under pressure through the porous medium module 20. Additionally, the hollow housing member 26 may axially support the porous medium module 20 when the porous medium module 20 is sealed in the porous medium module holder 40. Further, the hollow housing member 26 may serve as a container for the sealant 24 when the sealant 24 is applied to the porous media 22 and the porous medium supports 30, 32.
• the hollow housing member 26 may be configured in a variety of ways. For example, it may have a shape similar, or dissimilar, to the shape of the stack of porous media.
• the interior surface of the hollow housing member may be smooth or it may have a configuration, e.g., protrusions or indentations, that mechanically interlocks with the sealant.
• the hollow housing member comprises a hollow cylinder 26 concentrically arranged with the stack of porous media 22.
• the hollow cylinder has an inner diameter greater than the outer diameter of the stack of porous media 22, and the sealant 24 is disposed between them.
• the inner surface of the hollow cylinder 26 abuts the sealant 24 and may be smooth.
• the hollow housing member 26 may be fashioned from a variety of materials which provide sufficient strength to support the porous medium module 20.
• the hollow housing member 26 may comprise a metal, such as stainless steel.
• the hollow housing member may comprise a plastic material such as an engineering plastic.
• the plastic may comprise any suitable thermoplastic material, such as polypropylene, polysulfone, polyetheretherketone, or any other suitable engineering plastic.
• a thermoplastic material may be injection molded around the stack of porous media and porous medium supports, the thermoplastic material serving as both sealant and hollow housing member.
• a thermosetting material such as a polyurethane, may serve as both sealant and hollow housing member.
• Porous medium modules embodying the invention may be made in a variety of ways. For example, layers of porous media may first be stacked and axially compressed between opposite porous medium supports. The layers of porous medium may be compressed axially against one another as they are being stacked, or they may be laid one on another without compression and then axially compressed by pressing the porous medium supports against the stack. The stack, including the porous medium supports, may be compressed for a variety of reasons. For example, compressing the stack may provide even more uniform interfaces between adjacent layers and it may provide a greater amount of chromatographically active media within a given volume.
• Compressing the stack also aids in limiting the depth of sealant penetration, and providing a more uniform depth of sealant penetration, into the stack of porous media and porous medium supports.
• the amount of compression may depend on parameters such as the nature and thickness of each porous medium layer and the desired pressure drop through the stack of porous media.
• the stack preferably has a compression ratio in the range from about 70% or less to about 95% or more, preferably from about 75% to about 90% , more preferably from about 75% to about 85% , e.g., 80% .
• the hollow housing member 26, or any suitable device may be used as a stop to more precisely control the height of the stack after compression and consequently the amount of compression.
• the height of the hollow housing member 26 may be chosen to be about the same as the desired height of the stack after compression. The stack then may be compressed to the height of the hollow housing member 26, and the hollow housing member 26 may prevent the stack from being compressed further.
• the compression of the stack is maintained when the stack is disposed in the hollow housing member.
• the stack may be maintained in compression in any suitable manner, including by applying a weight to the top of the stack or by applying a predetermined pressure to the opposing porous medium supports by a mechanical or hydraulic press.
• a liquid sealant may be applied around the outer periphery of the stacked porous media and porous medium supports, preferably with the stack under compression.
• the stack may be maintained in compression in any suitable manner, including by applying a weight to the top of the stack or by applying a predetermined pressure to the opposing porous medium supports by a mechanical or hydraulic press.
• the compressed stack may be placed in a mold and a heated, liquid thermoplastic sealant may be inserted, e.g. , via an injection-molding technique, into the mold around the outer periphery of the stack.
• the areas of the mold which may come in contact with the sealant may be lined with teflon to prevent the sealant from being stuck to the mold.
• the temperature of the heated, liquid thermoplastic sealant is sufficiently low, or the heated liquid is cooled sufficiently quickly, that the porous media layers are not damaged by the heat.
• a thermosetting material or any other curable liquid sealant may be inserted into the mold around the outer periphery of the stack at room temperature. With the stack under compression, the liquid sealant, e.g. , the thermoplastic sealant or the thermosetting sealant, may penetrate to a more limited depth and more substantially uniformly radially into the stack as previously described. Pressure may be applied to the liquid sealant in the mold so that the liquid sealant may penetrate the side surface of the stack.
• the pressure at which the liquid sealant is applied to the stack may vary depending on such parameters as the type of sealant, the nature of the porous medium, and the desired depth and uniformity of penetration.
• the pressure may be less than about 5 psi, more preferably less than about 1 psi. In some cases, pressure may not be applied to the liquid sealant because the sealant can penetrate the side surface of the stack without pressure.
• a solid sealant may be placed in the mold around the outer periphery of the stack and may then be melted or softened to fill the mold around the outer periphery of the stack and to penetrate radially into the stack.
• the temperature of the melted or softened sealant is sufficiently low, or the melted or softened sealant is cooled sufficiently quickly, so that the porous media are not damaged by the heat.
• a pressure may be applied to the molten or softened sealant to assist it in filling the mold around the outer periphery of the stack and in penetrating into the stack.
• the solid sealant may include one or more pieces and may have any suitable configuration that allows it to be placed in the mold around the outer periphery of the stack.
• the solid sealant may include a single piece with a hollow, annular configuration, such as a hollow, cylindrical configuration, so that it can be placed around a cylindrical stack.
• the volume of the solid sealant is about the same as the volume of the sealant filling the mold around the outer periphery of the stack plus the volume of the sealant penetrating into the stack.
• the sealant when solidified in the mold, may substantially fill the mold and may be flush with the end surfaces of the stack, ensuring that the sealant substantially surrounds and seals the entire outer periphery of the stack.
• the solid sealant may be formed from any suitable material, such as thermoplastic material, e.g. , poly olef ins.
• the sealant is allowed to solidify, for example, by cooling in case of a heated, liquid thermoplastic sealant and/or by curing in case of a thermosetting sealant or any other curable liquid sealant.
• the solidified sealant seals the side surface of the stack of porous media and porous medium supports.
• the sealant also preferably joins, e.g. , bonds to or mechanically interlocks with, the porous medium supports and the porous media and substantially maintains them in position relative to one another, thereby maintaining the stack of porous media in compression.
• the sealed stack of porous media may be inserted inside the hollow housing member after the sealant solidifies.
• the hollow housing member may be inserted into the mold before the introduction of the liquid or solid sealant, or the hollow housing member may comprise the outer wall of the mold.
• the hollow housing member may be placed concentrically with respect to the stack of porous media with an annular space between the outer peripheral surface of the stack and the inner peripheral surface of the hollow housing member.
• the sealant may then be introduced into the space. As the sealant solidifies, it may bond to the hollow housing member, interlock with any configuration on the inner surface of the hollow housing member, and/or expand against the hollow housing member, securing the sealant and stack within the hollow housing member.
• a preferred mode of operation of a chromatography device of the present invention may be illustrated while referring to the embodiment shown in Figure 1. See previous application.
• a fluid such as a test sample or an eluent, may be introduced into the chromatography device 10 through the inlet passage 16.
• the fluid passes through the first flow distributor arrangement 52 into the porous media 22.
• the fluid passes from the inlet passage 16 through the first porous flow distributor 56 and into the tapered space 60.
• the flow distributor 56 may reduce flow disturbances, such as flow recirculation, vortices, and eddies, and flow non-uniformities as the fluid flows into the tapered space 60 from the inlet passage 16.
• the tapered space 60 preferably distributes uniformly the fluid from the inlet passage 16 to the porous medium module 20, which has a larger flow area than the inlet passage 16.
• the tapered space 60 enhances the distribution of the fluid from the inlet passage 16 to the second porous flow distributor, e.g., the porous medium support 30 of the porous medium module 20. From the tapered space 60, the fluid flows through the second flow distributor 30.
• the second flow distributor further reduces flow disturbances and enhances the uniformity of flow rates and residence times as the fluid flows from the tapered space 60 into the porous media 22.
• the fluid then passes through the porous medium module 20 and through the stack of porous media 22 with a substantially uniform flow front, which can be characterized by, for example, uniform flow velocity and/or uniform residence time for substantially all streamlines of the fluid.
• the porous medium module 20 includes a number of features, which allow the fluid to maintain a substantially uniform flow front. For example, as the fluid passes through the porous medium module 20, the substantially uniform inwardly facing surface which is defined by the sealant 24 penetrating into the side surface of the stack of porous media 22 and porous medium supports 30, 32, minimizes flow disturbances, such as flow recirculation, vortices, and eddies, and flow non-uniformities.
• the fluid streamlines at the outer portions of the supports and media are not unduly retarded by an uneven inwardly facing sealant surface. Further, undesirable mixing of the sample or eluent within the porous media supports 30, 32 and the porous media stack 22 is inhibited by the substantially uniform inwardly facing surface of the sealant.
• the fluid flows substantially evenly along the sealant surface without being drawn into and held up by any large nooks, crannies, or crevices in the sealant surface. Further, the fluid flows substantially evenly along the outer portions of the porous media supports 30, 32 and the stack of porous media 22 because the sealant forms a highly effective seal against radial leakage of the fluid.
• the fluid also flows substantially uniformly through the inner regions of the porous media stack 22.
• the fluid experiences a resistance to axial flow which is substantially uniform radially from the center to the outer portions of the stack.
• the porous media preferably have a substantially uniform thickness and permeability and the stack of porous media is uniformly compressed by the porous medium supports, providing a uniformly packed module having a resistance to axial flow which is substantially uniform radially. Further, undesirable mixing of the fluid in gaps and pockets between the porous media is prevented. Compressing the stack of porous media substantially eliminates these gaps and pockets. Consequently, the fluid flows axially through the stack of porous media with a substantially uniform flow front including uniform flow velocities and residence times within the stack.
• the fluid After passing through the porous media 22, the fluid passes through the second flow distributor arrangement 54 to the outlet passage 18.
• the fluid passes through the second porous flow distributor, e.g., the porous medium support 32, through the tapered space 62 through the first porous flow distributor 58 to the outlet passage 18.
• Each of the components of the second flow distributor arrangement 54 functions in a manner analogous to the components of the first flow distributor arrangement 52 to provide more uniform flow characteristics for fluid flowing to the outlet passage 18.
• the first porous flow distributor 58 may reduce flow disturbances as the fluid flows from the tapered space 62 into the outlet passage 18.
• the chromatography device 10 significantly enhances the chromatographic separations of the porous media 22.
• the chromatographic peaks may be much more narrow, well-separated and well-defined than those resulting from conventional chromatographic separations.
• the porous medium module 20 may be cleaned for use in another separation.
• the porous medium module may be removed from the housing and placed in a separate cleaning fixture or, preferably, the porous medium module may remain in the housing.
• a cleaning solution may then be passed through the porous medium module, including the porous media supports and the stationary separation medium, e.g. , the stack of porous media.
• One advantage associated with cleaning the porous medium module while it is in the housing is that the housing, including the walls of the tapered space, any porous flow distributor in the housing, and the fluid passages in the housing, are all cleaned along with the porous medium module.
• the cleaning solution may comprise any suitable cleaning agent, e.g., sodium hydroxide or hydrochloric acid in an aqueous solution at, for example, a one normal concentration.
• the cleaning solution is preferably directed in the opposite direction through the chromatography device, i.e. , from the outlet through the porous medium module to the inlet, but may be passed in either direction through the device. Because the sealant presents a substantially uniform inwardly facing surface within the porous media stack, flushing the porous medium module with a cleaning solution very thoroughly removes residue from the porous media.
• FIG. 5 illustrates another example of a chromatography device 110 embodying the invention.
• the chromatography device 110 may include an inlet 112, an outlet 114, a porous medium module 120, and a porous medium module holder 140 retaining the porous medium module 120.
• the chromatography device 110 may include first and/or second flow distributor arrangements 152, 154.
• the first flow distributor arrangement 152 may be disposed in the flow path between the inlet 112 and the porous medium module 120
• the second flow distributor arrangement 154 may be disposed in the flow path between the porous medium module 120 and the outlet 114.
• the exemplary embodiment 110 shown in Figure 5 is similar to the embodiment 10 shown in Figure 1 in many aspects. Thus, much of the discussion regarding the embodiment 10 shown in Figure 1 is applicable to this embodiment 110. This embodiment 110 will be described with the emphasis on the differences between the two embodiments 10, 110.
• the porous medium module 120 shown in Figure 5 may include a stack of porous media 122 and a sealant 124 disposed around the porous media 122.
• the porous medium module 120 may also include a hollow housing member 126, and the sealant 124 may be disposed between the stack of porous media 122 and the hollow housing member 126.
• the porous medium module 120 may also include first and/or second porous medium supports 130, 132 disposed respectively at the ends 125, 127 of the stack of porous media 122.
• the sealant 124 may also be similar to the sealant 24 shown in Figure 1.
• the sealant 124 may penetrate (1) radially (i.e.
• the sealant 124 which has penetrated the side surface 123 of the porous media 122, defines an inwardly facing side surface that forms the inner surface of the flow path through the porous media 122. Preferably, this surface is substantially free from crannies, crevices and other areas where fluid flow may stagnate.
• the sealant 124 may be made from any of the materials from which the sealant 24 may be made.
• the first and second porous medium supports 130, 132 may also be similar to the porous medium supports 30, 32 shown in Figure 1.
• the first and second porous medium supports 130, 132 may perform any of the functions that the porous medium supports 30, 32 perform, and may have any suitable configuration that allows them to perform one or more of the functions.
• the lateral dimension(s) of each medium support may be similar to those of the porous media or they may be larger or smaller.
• the porous medium supports 130, 132 extend laterally beyond the outer periphery of the stack of porous media 122 over a portion of the sealant 124.
• each porous medium support may vary along one or both of the lateral dimensions of the porous medium support.
• the porous medium supports 130, 132 each have a substantially constant thickness, although they may have a thickness varied to provide uniform flow through the chromatography device.
• the porous medium supports may have a conical configuration, which may be particularly suitable for chromatography devices of large sizes.
• the outer periphery of each porous medium support 130, 132 may be treated to reduce its permeability so that the depth of sealant penetration into the more permeable porous medium support 130, 132 is about the same as the depth of sealant penetration into the stack of less permeable porous media 22.
• the outer peripheral region of a porous medium support may be compressed to reduce its permeability by reducing the size of the pores or closing the pores.
• the outer peripheral region of a porous medium support can be compressed in a number of ways.
• the surfaces 168, 170, 172, 174 of the porous medium supports 130, 132 may be axially compressed near the outer periphery.
• the side surface 184, 186 of the porous medium supports 130, 132 may be compressed radially inwardly.
• the outer periphery of a porous medium support may be compressed at an angle between the axial and radial positions, producing a compressed, beveled outer edge.
• each porous medium support 130, 132 is axially compressed to form opposing circular grooves 131, 133 in the outer peripheral region inside the outer periphery.
• the opposed compressed grooves 131, 133 are particularly effective at reducing or preventing radially inward sealant penetration of the porous medium supports 130, 132 beyond the grooves 131, 133.
• the compressed grooves and the densified portions in each surface of the porous medium support may be offset or only one surface of the porous medium support may have a compressed groove and a densified portion, e.g. , the surface facing the porous media.
• the grooves are preferably configured as a continuous circle and may have any suitable cross section, such as a triangular, rectangular, or dome- shaped configuration, as shown in Figure 5.
• the outer peripheral region of the porous medium support may initially have a protrusion, such as a circular ridge, formed in one or both of the surfaces of the porous medium support in the outer peripheral region.
• the porous medium support initially has generally opposing circular protrusions in opposite surfaces of the support. These protrusions are then pressed to yield a generally flat surface on the porous medium support and a corresponding densified portion within the porous medium support.
• the outer periphery of the porous medium supports 130, 132 may be coated or impregnated with any suitable coating material to reduce its permeability.
• a suitable coating material may be applied to the area of a porous medium support 130, 132 which may come in contact with the sealant, such as the side surface 184, 186 and/or one or both of the end surfaces 168, 170, 172, 174 near the outer periphery.
• the coating material is not applied to the area of the porous medium supports 130, 132 through which the test sample or the eluent is intended to flow, to ensure that the fluid can flow through the porous medium support in an unobstructed, uniform manner.
• two or more layers of the same or different coating materials may be applied.
• Suitable coating materials may include a polymer, such as polyethylene, polyolefin, polypropylene, bicomponent polyurethane or teflon.
• a sealant may be used as a coating material.
• the coating may include one coat of teflon or one or two coats of bicomponent polyurethane.
• the coating material may be applied to the outer peripheral region in different ways to reduce sealant penetration.
• the grooves may be filled with a coating material or a sealant to reduce or prevent sealant penetration beyond the grooves .
• the grooves are preferably filled with the coating material to present a uniform, e.g., flat, face along the surface of the porous media support.
• the side surface and/or one or both of the flat surfaces between the compressed grooves and the outer edge may be coated or impregnated with a coating material.
• Another method of limiting sealant penetration of the porous medium supports involves applying a tape to the outer peripheral region of the porous medium supports to reduce sealant penetration.
• the tape may be applied to the side surface 184, 186 at the edge and/or one or both of the end surfaces 168, 170, 172, 174 near the outer periphery and even inwardly of the compressed grooves.
• the sealant may be applied to the porous media supports and the stack of porous media. After the sealant has solidified, the portion of the tape covering the test sample/eluent flow area of the porous medium supports may be peeled off. In this way, the sealant is prevented from obstructing the flow areas of the porous medium supports.
• the hollow housing member 126 shown in Figure 5 may be similar to the hollow housing member 26 shown in Figure 1. Further, the hollow housing member 126 may include a mechanism which interlocks the housing member 126 and the sealant 124.
• the mechanism includes a configuration on the housing member 126, which configuration may include, for example, one or more protrusions and/or indentations or any irregularities in the inner surface.
• the protrusions may include a circular ridge, an axial rib, or any other suitable projection.
• the indentation may include a recess, such as a circular or axial groove, or a hole.
• the configuration on the inner surface of the housing member creates a mating configuration on the outer surface of the sealant.
• the two configurations which are a mirror image of each other, interlock the housing member and the sealant and prevent relative movement between them.
• the configuration on the inner surface of housing member 126 includes indentations in the form of bevels 178, 180 at the ends of the housing member 126.
• the sealant 124 may protrude over the bevels 178, 180, interlocking with the bevels 178, 180 to prevent relative movement, e.g. , relative axial movement, between the housing member 126 and the sealant 124.
• the mating configurations may also be arranged to prevent relative rotational movement.
• the sealant serves this purpose.
• the sealant is securely attached to the porous medium supports, as well as the porous media, so that when the forces are removed, the porous medium supports remain in place and continue to compress the porous media.
• the sealant may be securely attached to the porous medium supports in many different ways.
• the sealant may be securely attached to the porous medium supports simply because it penetrates into the surfaces of the porous medium supports.
• the side surfaces of the porous medium supports may include protrusions and/or indentations so that the sealant may be more securely attached to the porous medium supports.
• the porous medium supports may extend into the sealant. In the embodiment 110 shown in Figure 5, the sealant 124 extends beyond the ends of the stack in the axial direction, and, as shown in Figure 8, a portion 188 of the sealant 124 may then extend radially inwardly over the end surfaces
• the sealant 124 acts as a clamp to more securely hold together the stack of porous media 122 and porous medium supports 130, 132, as well as preventing lateral displacement of the porous media supports and the porous media.
• the stack of the porous media and the porous medium supports is substantially concentrically arranged with the hollow housing member. Radial displacement of one or more of the porous media supports and the porous media may create a crevice or a nook at the edge of the test sample/eluent flow path, introducing flow nonuniformities.
• the porous medium module may include a mechanism which centers the stack of porous media and porous medium supports.
• the mechanism may include a plurality of spacers disposed between the housing member and the stack.
• the spacers preferably are dimensioned so that they center at least the stack of the porous media in the housing member.
• each spacer 182 has a cylindrical configuration, and the diameter of each spacer 182 is approximately equal to the difference between the inner radius of the housing member 126 and the outer radius of the stack.
• the spacers 182 are disposed around the stack between the housing member 126 and the stack, they center the stack within the housing member 126.
• the height of the spacers may be arranged to provide a stop for the porous media supports to facilitate adequate compression without over- compression as they are pressed against the porous media stack.
• the method of making the porous medium module 120 shown in Figure 5 may be similar to the method of making the porous medium module 20 shown in Figure 1.
• the method of making the porous medium module 120 is described below with the emphasis on the differences between the two methods.
• the outer peripheral regions of the porous media supports are preferably processed to reduce penetration of the sealant, as previously described. For example, opposing grooves may be pressed into the outer peripheral region and the grooves may be coated and/ or preferably filled with a coating material.
• the layers of porous media 122 may be compressed axially against one another as they are being stacked, or they may be laid one on another without compression and then axially compressed by pressing the porous medium supports 130, 132 against the stack.
• the hollow housing member 126 and the stack, including the porous media supports, may then be inserted into a mold (not shown).
• the hollow housing member 126 may comprise the outer sidewall of the mold, and the mold may close the open ends of the hollow housing member 126.
• Layers of porous media 122 and/or the porous medium supports 130, 132 preferably are centered in the hollow housing member 126.
• the stack of porous media 122 and porous medium supports 130, 132 is preferably stacked within the hollow housing member 126, and a plurality of spacers 182 may be placed between the housing member 126 and the stack of porous media 22 to center the stack in the housing member 126.
• the spacers 182 may be left in the hollow housing member 126, or they may be removed before the sealant is injected into the space between the hollow housing member 126 and the stack of porous media 122 and porous medium supports 130, 132.
• a split-ring centering mechanism may be used, or a centering member, e.g. , a centering ring may be used for each of the porous medium supports 130, 132 and the stack of porous media 122.
• the centering ring for each porous medium support 130, 132 preferably has an inner diameter substantially equal to the diameter of the porous medium support 130, 132 and an outer diameter substantially equal to the inner diameter of the hollow housing member 126.
• the centering ring for the stack of porous media 122 preferably has an inner diameter substantially equal to the diameter of the stack and an outer diameter substantially equal to the inner diameter of the hollow housing member 126.
• the porous media 122 and the porous medium supports 130, 132 may be centered in the hollow housing member 126 either at the same time or sequentially.
• one of the porous medium supports 130, 132 may be centered in the hollow housing member 126 with a centering ring.
• the centering ring may be removed, and a second centering ring may be used to center the porous media 122 in the hollow housing member 126.
• the second centering ring may be removed, and a third centering may be used to center the second porous medium support 130, 132 in the hollow housing member 126.
• the third centering ring may be removed. If the two porous medium supports 130, 132 have the same diameter, the first centering ring may be used to center the second porous medium support 130, 132.
• a sealant e.g., a liquid sealant, similar to the ones described above, may be applied around the outer periphery of the stacked porous media 122 and porous medium supports 130, 132, preferably after the stack has been compressed.
• the pressure at which the sealant is applied to the stack 122 may vary depending on the type of sealant, the nature of the porous media 122, and the desired depth and uniformity of penetration.
• the pressure is low.
• the pressure may be less than about 5 psig, more preferably less than about 1 psig, most preferably close to or at 0 psig.
• the housing member 126 includes a protrusion or an indentation such as the bevels 178, 180 shown in Figure 5, and the sealant is allowed to flow into the beveled areas. Further, the sealant may flow over the outer edge of each porous medium support 130, 132 and radially inwardly onto the outer surface 172, 168 of the porous medium support 130, 132 but preferably not beyond the compressed groove 131, 133.
• the sealant is allowed to solidify, for example, by cooling and/ or curing, preferably under pressure. Cooling and/or curing under pressure may reduce the formation of gas bubbles in the sealant as the sealant solidifies.
• the curing temperatures and pressures may vary depending, for example, on the sealant used. For example, for a bicomponent polyurethane, the curing temperature may be on the order of about 90°F and the curing pressure may be on the order of about 90 psig.
• the solidified sealant seals the side surface of the stack of porous media 122, as well as the outer periphery of the porous medium supports 130, 132.
• the sealant is also be securely attached to the porous medium supports 130, 132 and the porous media 22 so that the porous medium supports 130, 132 remain in place and maintain the stack of porous media 122 in compression.
• the porous medium module holder 140 may be similar to the porous medium module holder 40 shown in Figure 1.
• the porous medium module holder 140 preferably includes two plates 142, 144 between which the porous medium module 120 may be disposed. Connectors, such as a plurality of bolts 146 or clamps, may secure the porous medium module 120 between the two plates 142, 144.
• Connectors such as a plurality of bolts 146 or clamps, may secure the porous medium module 120 between the two plates 142, 144.
• the inlet 112 and outlet 114 are preferably placed near the center of the two plates 142, 144, respectively. Seals 148, 149 may be provided to prevent radially outward leakage between the porous medium module 120 and the plates 142, 144 of the porous medium module holder 140.
• each seal 148, 149 may be pressed against a plate 142, 144, and on the other side, the seal 148, 149 may be pressed against the porous medium module 120, for example, against one or more of the housing member 126, the sealant 124 and the porous medium support 130, 132.
• the seals 148, 149 are not pressed against only a permeable area of the porous medium supports, because there is a possibility that fluid may bypass the seal 148, 149 and leak radially outwards through the permeable area of the porous medium supports 130, 132.
• each seal 148, 149 is preferably pressed against the housing member 126, the sealant 124 or an impermeable area of the porous medium support 130, 132.
• each seal 148, 149 is placed near the outer edge of the porous medium module 120 outside of the flow area of the porous medium module 120.
• Each plate 142, 144 or the porous medium module 120, or both, may have an annular groove which serves as a seal gland to accommodate a seal 148, 149.
• each of the seals 148, 149 is placed in an annular groove in a plate 142, 144 of the module holder 140 and may be sealed against a porous medium support 130, 132 and/or the sealant 124.
• the seal 148, 149 may be sealed against an impermeable portion of the porous medium support 130, 132, which portion is impregnated with the sealant 124 and/or a coating material.
• the seal 148, 149 may be sealed against the sealant 124, the sealant 124 forming a portion of the seal gland.
• the sealant 124 may include a portion 135 extending radially inwardly over the outer surface 172 of the porous medium support 132 and a portion extending generally axially outwardly from the porous medium support 132. These two portions of the sealant form part of the seal gland.
• the seal 149 may be sealed against these portions of the sealant 124 in the seal gland to prevent radially outward leakage.
• the portion 135 of sealant 124 is smooth and flat so it can form a secure seal with the seal 149.
• the sealant may include only the generally axially extending portion of the seal gland, as shown in Figure 8.
• the seal 149 is the sealed against the sealant and the impermeable portion of the porous medium support.
• the embodiment shown in Figure 5 preferably includes both first and second flow distributor arrangements 152, 154, although it may include only one of the flow distributor arrangements 152, 154.
• the first flow distributor arrangement 152 preferably is disposed in the flow path between the inlet passage 112 and the porous medium module 120, where the inlet passage 112 has a smaller flow area than the porous medium module 120.
• the second flow distributor arrangement 154 preferably is disposed in the flow path between the porous medium module 120 and the outlet passage 114, and the porous medium module 120 has a larger flow area than the outlet passage 114.
• a flow distributor arrangement may be disposed at any place in the flow path where there is a change in flow area.
• the first flow distributor arrangement 152 preferably includes a tapered space 160.
• the tapered space 160 comprises at least a portion of the transition in the flow path between the smaller flow area of the inlet passage 112 and the larger flow area of the porous media 122.
• the first flow distributor arrangement may also include a porous flow distributor that is operatively associated with the tapered space.
• the porous flow distributor may be disposed at any suitable location, such as a location between the inlet passage and the tapered space, in the tapered space, between the tapered space and the porous medium module, or in the porous medium module.
• the porous flow distributor includes the first porous medium support 130 and is disposed in the porous medium module 120, although the porous flow distributor may be a part separate from the porous medium module 120 and the porous medium module holder 140.
• Alternative embodiments of the flow distributor arrangement are described in detail in previously referenced United States Patent Applications No. 60/121,701 and No. 60/1678,750 and the International Application titled "Chromatography Devices and Flow Distributor Arrangements Used in Chromatography Devices, " any of which embodiments may be used in the present example 110 of a chromatography device according to the present invention.
• the operation of the chromatography device 110 may be substantially the same as that of the chromatography device 10, which is described above.
• FIG 11 illustrates another example of a device 200 embodying the invention.
• the device may include an inlet 201, an outlet 202, a porous medium module 210, and a porous medium holder 220 retaining the porous medium module 210.
• the inlet 201 and the outlet 202 define a flow path through the device 200 and the porous medium module 210 is deposed in the flow path.
• the device 200 does not include any flow distributor arrangements.
• a flow distributor arrangement may be provided in the flow path between the inlet 201 and the porous medium module 210 and/or between the porous medium module 210 and the outlet 202.
• the porous media holder 220 preferably comprises holder sections such as two opposed plates 221, 222 which contain the porous medium module 210.
• the inlet 201 and the outlet 202 may be respectively disposed in the plates 221, 222.
• the porous medium module 210 may be used in a wide variety of separations.
• the porous medium module 210 may be used as a sampling module. Similar to the porous medium modules shown in previous embodiments, the porous medium module 210 shown in Figure 11 may include a stack of porous media 211 and a sealant 212 disposed around the porous media 211.
• the porous media 211 may be similar to the porous media of any of the previous embodiments.
• the porous medium module may include a hollow housing member disposed around the sealant, a first porous medium support disposed at one end of the porous media stack, and/or a second porous medium support disposed at the other end of the porous media stack.
• the porous medium module 210 preferably does not include a hollow housing member or any porous medium supports, having as its principal structural components only the stack of porous media 211 and the sealant 212.
• the sealant 212 may be similar to the sealant in any of the previous embodiments.
• the sealant 206 may penetrate (1) radially into the outer periphery of each porous medium 211 and/or (2) radially between adjacent porous media 211 to form a strong, effective seal and to ensure that the sealant 212 is securely bonded to the porous media 211.
• the sealant 212 may define an inwardly facing side surface that forms the inner surface of the flow path through the porous media 211. Preferably, this surface is substantially free of crannies, crevices and other areas where fluid flow may stagnate. However, the variation in sealant penetration may be larger than in previous embodiments.
• the porous media module 210 may be formed in a manner similar to any of the porous media modules of the previous embodiments.
• the layers of porous media 211 may be compressed, e.g., between opposed plates, and confined within a mold.
• the sealant 212 may then be applied around the outer periphery of the compressed porous media stack.
• the pressure at which the sealant is applied may vary depending on the type of sealant, the nature of the porous media, and the desired depth and uniformity of penetration.
• the sealant after it solidifies, may extend axially beyond one or both ends of the stack of porous media, but in the illustrated embodiment the sealant 212 is substantially even with the ends of the porous medium stack.
• the sealant 212 of the porous media module 210 preferably includes a seat arrangement 213 on one or both ends of the module 210.
• the seat arrangement 213 is operatively associated with a sealing mechanism, such as a circular seal edge 223, on the porous media holder 220.
• the configuration of the seat arrangement 213 may generally correspond to the configuration of the seal edge 223.
• the seat arrangement 213 may also be circular.
• opposing seal edges 223 are disposed on the plates 221, 222 and contact the seat arrangements 213 on opposite ends of the porous media module 210 when the plates 221, 222 are mounted to one another, e.g. , by a threaded connector or a clamping mechanism.
• the seat arrangement 213 may be contoured but is preferably flat and may be located outside of the effective flow area of the stack of porous media 211, preferably outside the outer diameter of the porous media 211.
• the sealant 212 is preferably compliant, e.g. , elastic.
• the sealant 212 may be formed from a compliant or resilient polyurethane.
• the module holder 220 may include stops 224 to prevent over compression of the sealant 212.
• the operation, including the cleaning, of the device 200 shown in Figure 11 may be similar to the operation of any previous embodiment.
• any and all of the methods for reducing the permeability of a porous medium support 130, 132 at its periphery which are discussed with respect to the embodiment 110 shown in Figure 5, can be used to reduce the permeability of a porous medium support 30, 32 at its periphery shown in Figure 1.
• the hollow housing member 126 may not include any configuration on its inner surface for interlocking the housing member 126 and the sealant 124. Accordingly, all features, modifications and variations of the disclosed embodiments are encompassed within the spirit and scope of the invention as currently or hereafter claimed.

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• 2000
  • 2000-02-25 EP EP00910329A patent/EP1155317A1/de not_active Withdrawn
  • 2000-02-25 CA CA002362589A patent/CA2362589A1/en not_active Abandoned
  • 2000-02-25 WO PCT/US2000/004746 patent/WO2000050888A1/en not_active Application Discontinuation
  • 2000-02-25 AU AU32441/00A patent/AU3244100A/en not_active Abandoned
  • 2000-02-25 JP JP2000601433A patent/JP2002538430A/ja active Pending

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