Cartridge type separation column and holder assembly for liquid chromatographs

Abstract

Plastic seal plugs insert into each end of an elution column tube and are provided with flat gasket portions extending laterally to cover each tube end, a spring loaded hand-tightenable nut drives an end fitting from each end of a column holder extending alomst the length of the column to put the gasket portions and the tube in compression and create a seal between the end fitting, tube, at interposed gasket, the latter being entirely contained against cold flow or deformation by a close fitting recess in the end fitting which entirely captures the plastic gasket and tube end.

What is claimed is: 
     
       1. In a liquid chromatograph (LC) system in which a liquid is delivered under pressure from a pump to an LC column, a replaceable column cartridge and holder assembly adapted for removal, shipment, and handling as a self-contained unit including an elongate cylindrical metal tube, a sorbant filling said tube, a pair of plastic seal plugs for closing the ends of said tube, each of said plugs being of T-shape in cross-section with a leg constructed to extend into a respective end of the tube and having a laterally extending end flange portion overlapping the tube at each end to its outer diameter, said tube, seal plugs and said sorbant together forming self-supporting replaceable LC cartridge, fittings for interconnecting the cartridge in the LC output line between the pump output and the LC detector system, each fitting having a cartridge receiving recess therein formed within the body of said fitting and so dimensioned as to receive the same in close fitting relation so that each recess extends at least over the flange portions of said plugs so that the latter totally confined within the recesses by their sidewalls and are axially confined between the cartridge tube and the floor of recess, means for supporting said cartridge and for yieldably urging the cartridge under pressure into sealing engagement between the fittings, the sealing surfaces comprising the floor of each recess, the tube ends, and the interposed seal plug flange, all of which are oriented in direct opposition to leakage forces, said means for urging the column into sealing engagement within said fittings including a holder having an effective length together with said fittings to extend somewhat less than the length of the column, and having threaded portions formed at each end thereof, cap nuts having an open end provided with an associated recess therein having threaded portions for engaging the threaded portions of each end of the holder, the other end of said nut being partially closed to form a cap having an aperture therethrough, said end fittings having a projection extending through the respective aperture and a body contained within said cap recess, and spring means interposed between at least one cap nut and associated end fitting for yieldably urging the latter into engagement with the interposed cartridge as the cap nuts are taken up against said spring means so that said cartridge is placed end to end compression by said holder, cap nuts, and interposed spring means. 
     
     
       2. A liquid chromatograph column assembly as in claim 1 wherein said seal portion laterally extends from and is integral with the plug and is in the shape of a flat disc like portion, and, further in which the floor of said recess and the end of said tube are flat so that the end cap brings sealing forces to bear upon the seal plug in exact opposition to the mechanical force developing the seal as the cap nuts are tightened. 
     
     
       3. A liquid chromatograph column assembly as in claim 1 in which the plug portion of said seal plug is provided with a recess therein facing into the column tube, and a filter disposed within said recess. 
     
     
       4. A liquid chromatograph column assembly as in claim 1 in which the plug portion is provided with an outwardly extending ridge and in which the tube is provided with a mating groove so that when the plug is fully inserted to bring the seal into engagement with the end of the tube the same is only removable with an excessive force to overcome the interfit between said groove and ridge. 
     
     
       5. An assembly as in claim 1 in which said spring washer is of the Bellville type and is disposed between said cap nut and said end fitting so that when assembled a preestablished compression force equal to the spring constant of the washer is reliably and repletably established in compression on the cartridge unit. 
     
     
       6. A column assembly as in claim 1 in which said end cap has a diameter of about 3/4 inch and is provided with a manually engageable surface, and in which said end nut and holder threads are about 18 per inch whereby said unit is hand-tightenable. 
     
     
       7. A liquid chromatograph column tube assembly as in claim 1 further in which said plug is provided with an outwardly facing circumferential rim intermediate its ends and transverse to its elongate dimension, and in which said tube is provided with an inwardly facing mating groove adjacent the end thereof for capturing the projection of the plug therein to reliably retain the same. 
     
     
       8. The system as in claim 1 wherein said plastic seal is selected from the group of polytetrafluoroethylene or polytetrafluoropropylene. 
     
     
       9. The system as in claim 1 wherein said spring means comprise Belleville washers interposed between each cap nut and the respective end fitting. 
     
     
       10. The system as in claim 1 further including a filter element, and in which said end plug is provided with a column facing recess for receiving and supporting said filter element. .Iadd. 
     
     
       11.  An improved column cartridge for use in a liquid chromatograph having a pump and connected to a column input line for delivering a sample and eluent under pressure to an LC column and a column output line connected from the column to a detector for analyzing the column output, said cartridge comprising a circularly cylindrical solid tube having a bore therethrough, a chromatograph sorbent disposed in said bore, filter and seal means arranged across the opening of the bore at each end of the tube and mounted with the tube and sorbent as a self-contained unit to permit the same to be independently handled, said cartridge having no mounting structure associated therewith normally used to apply any force between any part of the cartridge and any external member, a pair of end fittings, each having one end connected to one of said input/output lines and the other end connected and arranged for mating contact with a respective of said column cartridge, a seal interposed between each said end fitting and said column cartridge, said cartridge seal and each end fitting being constructed and arranged to mate and to center together so as to establish a high pressure sealing configuration when placed in axial compression, means for contacting the outer ends of said end fittings for placing the same under axially directed inward force pushing said fittings against the ends of said cartridge, said cartridge being constructed to receive the compression force created by said end fittings and contacting means. .Iaddend. .Iadd. 
     
     
       12.  A chromatograph column comprising a cartridge adapted to be connected to a chromatograph by input and output lines and removable from the system and reusable and resealable therein, said cartridge including a circularly cylindrical solid tube having a bore therethrough, a chromatograph sorbent disposed in said bore, means including a filter arranged across the opening of the bore at each end of the tube and mounted with the tube and sorbent as a unit to permit the same to be independently shipped, sold and used, said cartridge having no mounting structure associated therewith normally used to apply any force between any part of the cartridge and an external member, a pair of end fittings, each having one end connected to one of said input/output lines and the other end connected and arranged for mating contact with said column cartridge, a seal interposed between each said end fitting and said cartridge, said seal and each end fitting being constructed and arranged to mate and to center together so as to establish a high pressure sealing configuration when placed in axial compression, means for contacting the outer ends of said end fittings for placing the same under axially directed inward force pushing said fittings against the ends of said cartridge. .Iaddend. .Iadd. 
     
     
       13.  The liquid chromatograph as in claim 12 in which said means for contacting said end fittings comprises an elongate holder tube threaded at at least one end, cap nut means for engaging said holder tube threated end and for capturing said end fitting therein. .Iaddend. .Iadd.14. The liquid chromatograph as in claim 13 further including means disposed between said end cap means and said end fitting forming a bearing between the same as 
     
     
        the cap nut is taken up. .Iaddend. .Iadd.15.  An LC system in which a liquid is delivered under pressure to an elution column comprising, a replaceable cartridge carrying no structure for mounting the same and including an elongate cylindrical tube formed of a single piece of stock, said tube having an exterior surface which is circularly cylindrical from end to end, said tube having a bore therein extending from end to end, a sorbent filling said bore, filter means inserted in the bore at each end and affixed interiorily to said tube for closing the ends to form said cartridge into a self-contained structure capable of being handled and stored as a separate part independently of mounting structure, said tube, filter means, and sorbent being constructed and arranged as a symmetrical structure so that said cartridge is reversible, a pair of end fittings for connecting the cartridge into the LC output line between the LC pump and the LC detector system, each fitting having a cartridge receiving recess formed of a portion of the body of the fitting and so dimensioned as to mate with portions of the tube at the end thereof, one of said tube and said fittings having a recess therein in which the other member is confined axially and laterally and supported therein, sealing means interposed between cartridge and the respective end fittings and means for yieldably urging the end fittings into compression against the ends of the seals and cartridge, and means for urging the column into sealing engagement with the fittings including a holder having an effective length together with the fittings to extend somewhat less than the length of the column and having threaded portions of each end of the holder, the other end of the nut being partly closed to form a cap having an aperature therethrough, said end fittings having a projection extending through the respective aperature and the body contained within a capped recess, and means interposed between the capnut and the associated end fitting for yieldably urging the latter into engagement with the innerposed cartridge as the capnuts are taken up against the same whereby the cartridge is placed end-to-end compression by said holder, capnuts, and interposed means. .Iaddend. .Iadd.16. In an LC system in which a liquid is delivered under pressure to an elution column, a replaceable cartridge characterized by carrying no structure for mounting the same, a holder and end fitting assembly means for carrying all the mounting hardware for engagement of the cartridge for high pressure operation, said cartridge comprising an elongate cylindrical tube formed of a single piece of stock, said tube having an exterior surface which is circularly cylindrical from end to end, said tube having a bore therein extending from end to end, a sorbent filling said bore, filter means including a resilient seal inserted in the bore at each end and affixed interiorly to said tube for closing the ends; said tube, filter means, and sorbent being constructed and arranged as a symmetrical structure so that said cartridge is reversible, a sealing surface provided at each end of said tube and facing toward each end fitting, said end fitting having a sealing surface constructed to lie in sealing relation to said tube surfaces, seal means interposed between said sealing tube and end fitting surfaces, and having portions exposed for contact by the LC system end fittings, said seal and filter means being 
     
     
        formed as an integral unitary structure. .Iaddend. .Iadd.17.  A cartridge system for a liquid chromatograph in which a liquid is delivered under pressure to an elution column comprising a replaceable cartridge carrying no structure for mounting the same and including an elongate cylindrical tube formed of a single piece of stock, said tube having an exterior surface which is circularly cylindrical from end to end, said tube having a bore therein extending from end to end, a sorbent filling said bore, filter means inserted in the bore at each end and affixed interiorily to said tube for closing the ends to form said cartridge into a self-contained structure capable of being handled and stored as a separate part independently of mounting structure; said tube, filter means, and sorbent being constructed and arranged as a symmetrical structure so that said cartridge is reversible, a pair of end fittings for connecting the cartridge into the LC output line between the LC pump and the LC detector system, each fitting having a cartridge receiving recess formed of a portion of the body of the fitting and so dimensioned as to mate and seal with portions of the cartridge tube at the end thereof as the end fitting is placed in axially directed pressure against the ends of the cartridge, one of said tube and each said fitting having a recess therein in which the other member is confined axially and laterally and supported therein, sealing means interposed between each end of the cartridge and the respective end fitting, and means for yieldably urging the end fittings into axially directed compression against the ends of the sealing means of the cartridge to place the same under in axially directed pressure sufficient to obtain a direct, seal by axial compression between the ends of the cartridge and the axially directed portion of the recesses with the 
     
     
        end fittings. .Iaddend. .Iadd.18.  The system as in claim 17 in which said means for urging the end fittings is constructed and arranged for hand tightening such that fully effective sealing forces are obtained. .Iaddend. .Iadd.19. The system as in claim 18 in which said hand tightenable means comprises a holder in the form of a tube threaded at each end and extending coaxially of and around the cartridge, and capnuts threaded for engagement onto the holder and having portions thereof for engaging said end fittings for urging them against the ends of the cartridge. .Iaddend. .Iadd.20. The liquid chromatograph system as in claim 17 in which said means for urging the column into sealing engagement within the fittings includes a holder having an effective length together with the fittings to extend somewhat less than the length of the column and having threaded portions formed at each end thereof, capnuts having an open end having threaded portions for engaging the threaded portions of each end of the holder, the other end of the capnut being partly closed to form a cap portion having an aperture therethrough, said end fittings having a projection extending through the respective aperature and the 
     
     
        body which is contained within the capnut. .Iaddend. .Iadd.21.  A cartridge column system for a liquid chromatograph in which a liquid is delivered under pressure to an elution column comprising an end fitting assembly including means for carrying all the mounting hardware for end-to-end axial compression of the cartridge for high pressure sealing and operation, a replaceable cartridge characterized by an absence of structure for gripping or mounting the same, said cartridge comprising an elongate cylindrical tube formed of a single piece of stock strong enough to withstand end-to-end axial compression applied by the mounting hardware and transmitted end-to-end through the tube, said tube having an exterior surface which is circularly cylindrical from end to end, said tube having a bore therein extending from end to end, a sorbent filling said bore, filter means including a resilient seal inserted in the bore at each end and affixed interiorily to said tube for closing the ends; said tube, filter means, and sorbent being constructed and arranged as a symmetrical structure so that said cartridge is reversible, said seal having portions exposed for contact by the LC system end fittings. .Iaddend. .Iadd.22. The cartridge column system as in claim 21 in which said filter means includes plug means dimensioned to fit into and mounted to be retained in the respective end of the tube and a frit filter disposed in said plug means. 
     
     
        .Iaddend. .Iadd.23.  The cartridge column system as in claim 21 further including a seal integrally formed as part of said means and includes a plastic member having a surface adapted to be interposed between said end fitting and portions of said tube and constructed and arranged for sealing engagement therebetween as the urging means is taken up. .Iaddend. .Iadd.24. The cartridge column system as in claim 21 in which said seal means is formed in the shape of a "T" cross-section the arms of which extend laterally over the ends of the tube, the base of which contains said filter and forms a projection extending into the end of the tube for being retained therewith. .Iaddend. .Iadd.25. The cartridge column system as in claim 21 in which said tube is provided with a sealing surface facing toward each end fitting, and in which said end fitting is provided with a sealing surface constructed to lie in sealing relation to said tube end surface, and further including seal means interposed between said sealing tube and end fitting surfaces. .Iaddend.