Abstract:
A capillary tube liquid transport device adapted to make nano-sized capillaries (5 μm to 180 μm) resilient. A first nano-capillary has a first sleeve about an inlet end that provides a resilient surface for installation of a fitting. The nano-capillary has a second sleeve about an outlet end that deforms to grip the outlet end of the capillary and hold it tightly against a transport tubing capillary. An outer sleeve is attached to the two end sleeves retaining them in a spaced relationship and providing support for the capillaries. The entire device is relatively rugged and easy to handle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of and is a continuation of International Application No. PCT/US2004/006712, filed Mar. 5, 2004 and designating the United States, which claims benefit of a priority to U.S. Provisional Application No. 60/652,742, filed Mar. 7, 2003 (attorney docket number WAA-313). The content of which is expressly incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to a capillary structure that may include a column and more particularly to an assembly that stabilizes a capillary for ease of use in a liquid chromatography application.  
       BACKGROUND OF THE INVENTION  
       [0003]     Capillary liquid chromatography (LC) is a micro-version of traditional liquid chromatography. Capillary LC columns have extremely low solvent consumption and require ultra-low volumes of samples for analysis, and hence provide high efficiency separations. Nano LC is an even smaller version of Capillary LC, typically utilizing capillaries having an inner diameter between 5 μm and 180 μm. The smaller dimensions of Nano columns require even less solvent and samples for analysis. The output from the Nano LC columns is in sufficiently small volumes that it is well suited to provide samples to be analyzed by a mass spectrometer. Nano LC systems consist essentially of a nano-pump, a nano column, connection mechanisms for the nano column, a detector, and data processing capabilities. The connection mechanisms are an important part of the system, because they present opportunities for mismatch which at these volumes lead to bandspreading in the resultant analysis.  
         [0004]     Different types of materials, such as fused silica, stainless steel, and polymer, have been used for capillary columns. Due to their unique features, fused silica capillaries are the most common for preparation of nano LC columns. It is easy to control the dimensions of fused silica capillaries during manufacturing and the capillaries do not deform when packed. Further, the wall of a fused silica capillary is smooth, which is very desirable for transport of small volumes of fluids.  
         [0005]     However, fused silica capillaries have certain limitations. The most significant limitation stems from the brittle and fragile nature of the glass-like material from which they are made. The frangible nature of a thin, fused silica tube makes packing, shipping, and handling difficult. Typically, a layer of polyimide is coated on the outside of the fused silica capillary for protection. However, if the polyimide layer has incurred even a small scratch during production or handling, it will lose its protective effect and the capillary can break with just a gentle touch.  
         [0006]     In the prior art, capillary columns to be used with a mass spectrometer have been transported as systems composed of a packed nano capillary that is bonded to a transport tube for connection with a mass spectrometer. The bonding agent is usually a fluoropolymer resin sleeve union. These column systems do not usually incorporate a frit into the column although an inlet filter may be packed separately with column. The user is left to determine whether the filter is required and to install it with the column. To assemble the column into a system, the user assembles the column input end into a fitting that matches the injector of the HPLC equipment being used. This involves placing the filter into the fitting, aligning the column and filter against the fitting leaving no dead space, and then tightening the assembly together. A skilled person is needed to assemble this end without breaking part of the column or introducing dead volume, that leads to bandspreading that negatively impacts the performance. During this operation, the transfer tube will be exerting stresses on the bonded joint possibly introducing dead volume into the joint.  
         [0007]     The transport tube is required to connect the output of the Nano LC column to an electro-spray source of a mass spectrometer. The outlet of the prior art the column is connected to the transport tubing with a small piece of tubing that compresses the outside diameter of the mating capillaries and forms a flow path. This junction is very weak and susceptible to breakage or additional bandspreading.  
         [0008]     Fused silica capillaries are extremely fragile and difficult to work with. Extreme care must be taken when handling and connecting the column to an HPLC system. A sleeve must be added to the prior art capillaries to allow tightening and swaging an end-fitting on the inlet end of the capillary column. A flexible sleeve is employed that compensates for the size of the capillary, which is too narrow for typical fittings.  
         [0009]     There is a need, therefore, for a device that can protect the capillary column and form a user-friendly package that can be installed without extreme caution. This liquid transport capillary must alleviate the other shortcomings of the fragile fused silica capillary.  
       SUMMARY OF THE INVENTION  
       [0010]     The device built according to the invention overcomes the issues described above. The device is adapted to accommodate both a central nano capillary and a central nano column.  
         [0011]     One embodiment of the present invention is directed to a device used to transport liquids through nano-scale capillary tubes. The device is built around a first cylinder having a wall. The wall has an interior surface and an exterior surface. This first cylinder has a first end, usually connected to an inlet mechanism, and a second end, usually connected to an outlet system. The interior volume of the first cylinder, surrounded by the interior surface, defines a chamber for receiving a liquid sample. A second cylinder is placed over the first end of the first cylinder. This second cylinder has a wall with an interior surface and an exterior surface, and the cylinder has a first end and a second end. When the second cylinder is placed concentrically about the first end of the first cylinder, the interior surface of the second end of the second cylinder is secured to the exterior surface of the first cylinder. The wall of the second cylinder has a thickness so that the resultant end of the assembly is thicker than the first cylinder. When the second wall is of a resilient material, it can be used to secure a fitting to the device. The second cylinder is sized so that the second cylinder occupies a position covering only a portion of the first cylinder. For liquid chromatography, the first and second cylinders are preferentially positioned with their first ends aligned, but the ends can be positioned relative to each other as best suits the application.  
         [0012]     A third cylinder is placed over the second end of the first cylinder. The third cylinder has a wall with an interior surface and an exterior surface, and the third cylinder has a first end and a second end. When the third cylinder is placed concentrically about the second end of the first cylinder, the interior surface of the first end of the third cylinder is secured to the exterior surface of the first cylinder. The wall of the third cylinder has thickness so that the resultant end of the assembly is thicker than the first cylinder. This provides an easier to handle surface for mating with further cylinders such as a transfer tube. The third cylinder is sized so that the third cylinder occupies a position covering only a portion of the first cylinder. The second end of the third cylinder may extend beyond the limits of the second end of the first cylinder, but that relationship may be varied as required for connection purposes. In a preferred embodiment, the second end of the third cylinder projects outward from the second end of the first cylinder to provide a receiving pocket for a transport tube. Note that a portion of the first cylinder is not covered by either of the second cylinder or the third cylinder. In a preferred embodiment, the majority of the first cylinder is not covered.  
         [0013]     A fourth cylinder sheathes the assembly of first, second and third cylinders. The fourth cylinder has a wall having an interior surface and an exterior surface. The first end of the fourth cylinder overlaps and is fastened to a portion of the first cylinder/second cylinder assembly and the second end overlaps and is fastened to the first cylinder/third cylinder assembly. In a preferred embodiment, the second end of the fourth cylinder covers the region where the third cylinder covers the first cylinder and extends to the second end of the third cylinder and in some cases beyond the second end. The fourth cylinder, so connected, stabilizes and supports the first, second and third cylinders by keeping the cylinders in a constant relationship and providing thickness to support connections to fluid transport means.  
         [0014]     The device described above has superior operating characteristics when installed in a nano-scale fluid transport system because the assembly is manufactured with better tolerances than can be achieved in the field. Further, the scale of the device is easier to handle allowing a technician to install it more easily. The device can be manufactured to accommodate a known connection configuration, so that dead space in the resultant connection is minimized.  
         [0015]     In a preferred embodiment, the first cylinder is implemented as a column, where the chamber is filled with chromatographic media. A frit may be formed in either or both ends of the first cylinder to secure the media in the chamber and to filter liquids entering and exiting the column. The device with a central column is well suited to be field fitted with a fitting compatible with the HPLC equipment being used. Further, the open end of the third cylinder is ready to receive a transport tube that can be butted flush with the second end of the column.  
         [0016]     In a further embodiment, a fifth cylinder is added to the device previously described. A conduit through the fifth cylinder that can transport a liquid is defined by an interior surface. When the first end of the fifth cylinder is placed inside the second end of the third cylinder, the external surface engages with the interior surface of the third cylinder. In order to limit dead space, the first end of the fifth cylinder is butted against the second end of the first cylinder leaving no space therebetween. For best performance, the outside diameter of the fifth cylinder is substantially equal to the outside diameter of the first cylinder and the diameter of the conduit is equal or less than the diameter of the chamber of the first cylinder. It is preferred that the diameter of the conduit be less than the diameter of the chamber for liquid chromatography applications. The fifth cylinder may be substantially longer than the other cylinders and function as transport tube to, for instance, a mass spectrometer.  
         [0017]     In an advantageous embodiment of the devices described above, the fourth cylinder is a tube of heat shrinkable material. The inner diameter of the fourth cylinder before shrinking is approximately the same as the outer diameter of the second and third cylinders, which are approximately equal. This allows the fourth cylinder to be easily slipped over the first, second and third cylinder assembly. The inner diameter of the heat shrink fourth cylinder, once shrunken, is approximately one-half the pre-shrunken diameter. In a preferred configuration, the shrunken inner diameter of the fourth cylinder is greater than the outer diameter of the first cylinder, allowing the fourth cylinder to protect the first cylinder without limiting its flexibility. The shrinking action of the fourth cylinder retains the cylinders in the fixed relationship of their assembly, making the whole assembly more immune to shocks and breakage. When the fifth cylinder, or transfer tube, is joined to the assembly of cylinders before the fourth cylinder is threaded over the assembly, the fourth cylinder may extend beyond the second end of the third cylinder. While the in the preferred embodiment, where the first and fifth cylinders have the same outer diameter, the heat shrunk cylinder will not grip the outer surface of the fifth cylinder, it will provide support to the butted junction between the first and fifth cylinders.  
         [0018]     In one embodiment, the invention is implemented as a liquid chromatography column device with a column that is sized and dimensioned for chromatographic use. The column element has an internal cavity with a first and a second end and a longitudinal axis. A first cylindrical element is disposed about the column first end, forming a reinforced first region of the column. A second cylindrical element is disposed about the column second end. A third cylindrical element has a first end concentrically disposed on the first cylindrical element and a second end concentrically disposed on the second cylindrical element. The third cylindrical element is secured to the cylindrical elements that are encircled thereby stabilizing the liquid chromatography column while allowing it to remain flexible. The column device so assembled is ready to be directly coupled to liquid chromatography equipment in a manner that minimizes column dead volume.  
         [0019]     This column device is preferred when the column is nano sized, such as those used for nano-spray applications. The column, in some embodiments, has the external surface of the wall covered by a protective coating applied to the column during manufacturing of the capillary that is the basis of the column. In some embodiments, the concentric first column end and end of the first cylindrical element co-terminate in a plane perpendicular to the longitudinal axis providing a flat surface that can be attached to an injector without increased bandspread.  
         [0020]     In one embodiment, the column second end terminates at a midpoint of the second cylindrical element. This provides a socket for a transport tube to be inserted in the field. Alternately, the column is made with a transport tube having a wall structure defining a tubing cavity installed in the second end of the second cylindrical element. Installing the transport tube during manufacture of the column device allows fixtures to be used that minimize bandspreading and assure that the first end of the tubing and the second end of the column element are disposed in butting relationship and are perpendicular to the longitudinal axis of the column element. In an embodiment, the second cylindrical element holds the column element and the tubing together.  
         [0021]     In a further embodiment, the liquid chromatography column described above also comprises a fitting disposed about and secured to the reinforced first region of the column element. The fitting is installed so that a portion of the reinforced first region protrudes from a first side of the fitting with a larger portion of the reinforced first region extending under the fitting and along a portion of the column. The fitting manufacturer typically specifies the extent of the protrusion of the column element from the fitting. One fitting used comprises a ferrule portion and a nut portion. The ferrule portion is crimped to the reinforced first region while the nut portion slides freely over the external surface of the first cylindrical element. The nut is retained by the third cylindrical element that is disposed around the second end of the first cylindrical element and provides too big a diameter to pass under the nut. In one embodiment, the capillary of the column element is made of fused silica, the first cylindrical element is made of polyetheretherketone (PEEK®) material, the second cylindrical element is made of a fluoropolymer resin such as Teflon® FEP material and the third cylindrical element is made of a heat-shrink tubing. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0022]     For a fuller understanding of the nature and advantages of the invention, reference should be had to the detailed description taken in conjunction with the accompanying drawings in which:  
         [0023]      FIG. 1A  is a cross sectional view of a device according to the invention;  
         [0024]      FIG. 1B  is a cross sectional view of a device with a frit according to the invention;  
         [0025]      FIG. 2  is a cross sectional view of a device with a transport tube according to the invention;  
         [0026]      FIG. 3  is a cross sectional view of a device with a processed central cylinder according to the invention;  
         [0027]      FIG. 4  is a cross sectional view of a device according to the invention;  
         [0028]      FIG. 5  is a cross sectional view of a device with heat guards according to the invention;  
         [0029]      FIG. 6  is a cross sectional view of a device with a fitting according to the invention;  
         [0030]      FIG. 7  is a cross sectional view of a device with a fitting and transport tube according to the invention;  
         [0031]      FIG. 8  is a cross sectional view of the device of  FIG. 7  with a frit according to the invention; and  
         [0032]      FIG. 9  is a cross sectional view of the device of  FIG. 8  with a heat shrunk enclosing cylinder according to the invention. 
     
    
     DETAILED DESCRIPTION  
       [0033]     The present invention will be described in detail as a device for transporting liquids, performing chromatography and linking other instruments including, by way of example, a mass spectrometer to a liquid chromatograph. However, it must be appreciated that these are preferred embodiments and the invention can be applied in other ways as will be appreciated by those who are skilled in the art.  
         [0034]     A preferred embodiment of the invention is used to transport liquids through nano-scale capillary tubes.  FIG. 1A  illustrates a basic version of this device  8 . The device is built around a first cylinder  10  having a wall  12 . The wall  12  has an interior surface  14  and an exterior surface  16 . This first cylinder has a first end  18 , usually connected to an inlet mechanism, and a second end  20 , usually connected to an outlet system. The interior volume of the first cylinder  10 , surrounded by the interior surface  14 , defines a chamber  22  for receiving a liquid sample.  
         [0035]     A second cylinder  24  is placed about the first end  18  of the first cylinder  10 . This cylinder  24  has a wall  26  with an interior surface  28  and an exterior surface  30 , and the cylinder  24  has a first end  32  and a second end  34 . When the second cylinder  24  is placed concentrically about the first end  18  of the first cylinder  10 , the interior surface  28  of the second cylinder  24  is secured to the exterior surface  16  of the first cylinder  10  by methods such bonding or crimping as are known in the industry. The wall  26  of the second cylinder  24  has a thickness so that the resultant end of the assembly is thicker than the first cylinder  10 . When the second wall  26  is of a resilient material, it can be used to secure ends such as a fitting (not shown) to the device. The second cylinder  24  is sized so that the second cylinder  24  occupies a position covering only a portion of the first cylinder  10 . The first and second cylinders  10 ,  24  are shown in  FIG. 1  with their first ends  18 ,  32  aligned. Alternately, the ends can be positioned relative to each other as best suits the application. However, when the application is liquid chromatography, aligning the ends is preferred.  
         [0036]     A third cylinder  36  is placed over the second end  20  of the first cylinder  10 . This cylinder  36  has a wall  38  with an interior surface  40  and an exterior surface  42 , and the third cylinder  36  has a first end  46  and a second end  44 . When the third cylinder  36  is placed concentrically about the second end  20  of the first cylinder  10 , the interior surface  40  of the third cylinder  36  is secured to the exterior surface  16  of the first cylinder  10  by methods such as bonding, press fit, or by resilience in the material of the third cylinder. The wall  38  of the third cylinder  36  has thickness so that the resultant end of the assembly is thicker than the first cylinder  10 . This provides an easier to handle surface for mating with further cylinders such as a transfer tube. The third cylinder  36  is sized so that the third cylinder  36  occupies a position covering only a portion of the first cylinder  10 .  FIG. 1  illustrates the second end  44  of the third cylinder  36  extending beyond the limits of the second end  20  of the first cylinder  10 , but that relationship may be varied as required for connection purposes. In a preferred embodiment, the second end  44  of the third cylinder  36  projects outward from the second end  20  of the first cylinder  10  to provide a receiving pocket for a transport tube. Note that a portion  23  of the first cylinder  10  is not covered by either of the second cylinder  24  or the third cylinder  36 . In a preferred embodiment, the majority of the first cylinder  10  is not covered.  
         [0037]     A fourth cylinder  48  sheathes the assembly of first, second and third cylinders  10 ,  24 ,  36 . The fourth cylinder  48  has a wall  50  having an interior surface  52  and an exterior surface  54 . The first end  56  of the fourth cylinder overlaps and is fastened to a portion of second cylinder  24  and the second end  58  overlaps and is fastened to the third cylinder  36 . In a preferred embodiment, the second end  58  of the fourth cylinder  48  covers the region where the third cylinder  36  covers the first cylinder  10  and extends almost to the second end  44  of the third cylinder  36 . The fourth cylinder  48 , so connected, stabilizes and supports the first, second and third cylinders by keeping the cylinders in a constant the relationship and providing thickness to support connections to fluid transport means.  
         [0038]     The device described above has superior operating characteristics when installed in a nano-scale fluid transport system because the assembly can be manufactured with better tolerances than can be achieved in the field. Further, the scale of the device is larger and easier to handle allowing a technician to install it more easily. The device can be manufactured to accommodate the connection configuration of a site, so that dead space in the resultant connection is minimized. When a fluid transport tube will be installed in the field, it is preferable that the third and fourth cylinders  36 ,  48  be made of a transparent material so that the technician can see the quality of the joint between the transport tube and the first cylinder  10  (flow joint) to minimize dead volume.  
         [0039]     In a preferred embodiment shown in  FIG. 1B , the first cylinder  10 ′ is implemented as a column, where chamber  22  is filled with HPLC packing material as is known in the industry. A frit  60  may be formed in either or both ends of the first cylinder  10 ′ to secure the media in the chamber  22  and to filter liquids entering and exiting the column  10 ′. The device  8 ′ with a central column  10 ′ is well suited to be field fitted with a fitting compatible with the HPLC equipment being used. Further, the open end  44  of the third cylinder is ready to receive a transport tube that can be joined flush with the second end  20  of column  10 ′.  
         [0040]     In a further embodiment as shown in  FIG. 2 , a fifth cylinder  62  is added to the device  8 ′ previously described. The fifth cylinder  62  has a wall  68  with an interior surface  64  and an exterior surface  66 , and the fifth cylinder has a first end  70  and a second end  68 . A conduit  72  through the fifth cylinder  68  that can transport a liquid is defined by the interior surface  64 . When the first end  70  of the fifth cylinder  68  is placed inside the second end  44  of the third cylinder  36 , external surface  66  engages with the interior surface  40  of the third cylinder  36 . In order to limit dead space, the first end  70  of the fifth cylinder  68  is butted against the second end  20  of the first cylinder  10 ′ leaving no space therebetween. For best performance, the outside diameter  80  of the fifth cylinder  62  is substantially equal to the outside diameter  78  of the first cylinder  10 ′ and diameter  76  of the conduit  72  is equal or less than the diameter  74  of the chamber  22  of the first cylinder  10 ′. It is preferred that the diameter  76  of the conduit  72  be less than the diameter  74  of the chamber  22 . The fifth cylinder  62  may be substantially longer than the other cylinders functioning as transport tube to, for instance, a mass spectrometer.  
         [0041]     In an advantageous embodiment of the devices described above, the fourth cylinder  48  is a tube of heat shrinkable material. The inner diameter  75  of the fourth cylinder  48  before shrinking is approximately the same as the outer diameter  77  of the second cylinder  24 , which is approximately equal to the outer diameter  79  of the third cylinder  36 . This allows the fourth cylinder to be easily slipped over the first, second and, third cylinder assemblies. The inner diameter  75  of the shrunken heat shrink fourth cylinder  48  is approximately one-half the pre-shrunken diameter. In a preferred configuration, the shrunken inner diameter of the fourth cylinder  48  is greater than the outer diameter  78  of the first cylinder  10 ′, allowing the fourth cylinder  48  to protect the first cylinder without limiting its flexibility. The shrinking action of the fourth cylinder retains the cylinders  10 ′,  24  and  36  in the fixed relationship of their assembly, making the whole assembly more immune to shocks and breakage. When the fifth cylinder  62  is joined to the device  8 ′ before the fourth cylinder  48  is threaded over the assembly, the fourth cylinder  48  may extend beyond the second end  44  of the third cylinder  36 . While in the preferred embodiment, where the first and fifth cylinders  10 ′,  62  have the same outer diameter, the heat shrunk cylinder will not grip the outer surface  66  of the fifth cylinder  62 , it will provide the support to the butted junction  81  between the first and fifth cylinders  10 ′,  62 .  
         [0042]     In most embodiments, the first cylinder  10 , and fifth cylinder  62  are very flexible being composed of nano diameter silica glass. The second cylinder  24  and third cylinder  36 , having a larger inner diameter, exhibit less flexibility. This reduced flexibility provides support for the first and fifth cylinders  10 ,  62  and any junctions encased by the second and third cylinders  24 ,  36 .  
         [0043]      FIG. 3  illustrates an option to improve the flow junction  81 . The thickness of the wall  12  at the second end  20  of the first cylinder  10  is reduced by a means such as heating so that the outer diameter  82  of the extreme second end  20  of the first cylinder  10  is reduced. This operation leaves a step down in diameter circumscribing the second end  20 . If the third cylinder  36  is sized to be a tight fit about the normal diameter  80  of the first cylinder, then, when the third cylinder  36  is softened to allow the first cylinder  10 ′ to be threaded through the third cylinder  36 , the stepped down region can get backfilled with softened material. This backfilled material is available for the fifth cylinder  62  to bond to when the fifth cylinder  62  is inserted while the third cylinder  36  is still softened. The backfilled material and tight-fitting third cylinder  36  significantly increases the strength of the junction between the first and fifth cylinders  10 ′,  62 .  
         [0044]      FIG. 4  illustrates that the flow junction  81  improvement can be combined with building a frit  60  in the first cylinder  10 ′ when the first cylinder is filled with HPLC packing material. One way of forming the frit  60  at the end  20  of the column  10  is by treating and then heating the treated HPLC packing material. In a last step, the very end  85  of the frit  60  is sintered. During the sintering step, the wall  12  is reduced in thickness for length  84 . This step provides a self-contained frit  60  while providing the structure to improve the bond around junction  81  as discussed above.  
         [0045]      FIG. 5  illustrates an alternate assembly in the region of the third cylinder  36 . When it is desired to further isolate the first and fifth cylinders  10 ′,  62  from any heating effects while shrinking the fourth cylinder  48 , heat protecting tubes  86 ,  88  are placed around the first and fifth cylinders respectively before the third cylinder is installed. When the third cylinder is installed, it is therefore spaced apart from the liquid carrying first and fifth cylinders  10 ′,  62 . In applications where the third cylinder is softened before being installed to facilitate forming the junction  81 , the heat protecting tubes  86 ,  88  prevent any softened material from entering the fluid carrying portions of the cylinders. Further, when the fourth cylinder  48  is heated to cause the shrinking, the tubes  86 ,  88  isolate the first and fifth cylinders  10 ′,  62  from that heat.  
         [0046]      FIG. 6  illustrates an installation of a fitting  90  on the nano capillary transport device  8  creating a insertable device  102 . The fitting shown has a ferrule  92  and a nut  94  as is known in the art. The specifics of the fitting chosen are tailored to match the port of the instrument used. The ferrule  92  is swaged onto the second cylinder  24  either in a bonding action that connects the three components, the ferrule  92 , second cylinder  24 , and first cylinder  10 , together or in a separate operation after the first and second cylinders  10 ,  24  have been joined. The spacing between the ferrule  92  front edge  100  and the ends of the cylinders  18 ,  32  is specified for each fitting  90  and the insertable device  102  is manufactured to precisely meet these specifications, thereby limiting dead volume. When the fourth cylinder  48  is installed, it terminates short of the fitting  90  providing a space  96  to allow the nut  94  to be retracted from the ferrule  92 .  
         [0047]     In  FIG. 7 , the insertable device  102  is made more installable by connecting the fifth cylinder  62  to the insertable device. The flow junction  81  between the first and fifth cylinders  10 ,  62  is formed in the factory where conditions are controlled and repeatable. In manufacturing device  104 , the fourth cylinder  48  is not put in place until after the fifth cylinder  62  is joined to the insertable device  102 , allowing an opaque material to be used for the fourth cylinder  48 . This allows the joining of the flow junction  81  to be carried out under a microscope, minimizing dead volume. Teflon° FEP is one preferred material for third cylinder  36  because it is transparent, allowing the joining to be visually monitored. Although  FIG. 7  illustrates the fourth cylinder  48  terminating short of the end of the third cylinder  36 , is it preferred to extend the fourth cylinder  48  a small distance down the length of the fifth cylinder  62  to provide support.  
         [0048]      FIG. 8  illustrates a device  106  with a column  10 ′ incorporating a frit  60  built up like in the previous device  104 . The fitting  90  makes device  106  insertable while the integration of the cylinders into a unit by the fourth cylinder  48  makes the device safe to handle with reasonable rather than extreme care.  
         [0049]      FIG. 9  illustrates a device  108  incorporating all the features previously discussed. The first cylinder  10 ′ is configured as a column with a frit  60  that has been sintered at its second end  20 . The first and fifth cylinders  10 ′,  62  are joined at the mid-point of the third cylinder  36  with a butt joint  81  that allows no dead volume. The fitting  90  is installed at the first, inlet, end  18  of the column  10 ′ with room for the nut  94  to disengage from the ferrule  92 . The fourth cylinder has been heat shrunk and is in its shrunken state  48 ′ where it has less thickness and grips the second and third cylinders  24 ,  36 . Note that the shrunken fourth cylinder  48 ′ comes close to the first cylinder  10 ′ without gripping the outer surface  16 .  
         [0050]     The inside diameter of the first and fifth cylinders ranges between 5 μm and 180 μm. The diameter of the fifth cylinder  62  is equal or less than the diameter of the first cylinder  10 .  
         [0051]     A preferred method of making device  108  starts with filling a first nano-capillary  10  with HPLC packing material. The ends of the HPLC packing material are processed to form frits  60  at the ends of the first capillary. The outlet end  20  is processed such that a reduced outer diameter is formed for a portion  84  of end  20 . The inlet end  18  is processed without this effect. The second cylinder  24  made of polyetheretherketone resin (PEEK™), chosen for its resistance to chemicals and resilience, is slipped over the first, inlet, end  18  of the first capillary  10 ′. The concentric ends  18 ,  32  are placed in a fixture (not show) that aligns the ends as required by the fitting  90  to be used. The fitting ferrule  92  is slipped over the first and second cylinders  10 ′,  24  and into the fixture. The ferrule  92 , second cylinder  24  and first capillary  10 ′ are swaged together forming the inlet side of the device  108 . The nut portion  94  of the fitting  90  is slid over the first cylinder  10 ′ and the first and second cylinder reinforced section, to rest near the ferrule  92 .  
         [0052]     The third cylinder  36 , preferably made of Teflon® FEP that has an inner diameter slightly less than the outer diameter of the first cylinder  10 ′ is heated until soft and moldable. The second end  20  of the first cylinder  10 ′ is pushed through the softened third cylinder  36 . Because of the reduced outer diameter of this end  20 , it passes easily through the third cylinder  36  with no material from the third cylinder  36  blocking the chamber in the first cylinder  10 ′. However, the inner diameter of the third cylinder is expanded by the passage of the full diameter part of the end  20 . Once the end  20  has passed through the whole length of the third cylinder  36 , it is retracted to the midpoint of the third cylinder. Some of the material of the third cylinder  36  accumulates where the first cylinder  10 ′ changes diameter. The end  20  of the first cylinder  10 ′ is placed under a microscope focused where the flow junction  81  will be formed. The first end  70  of the fifth cylinder  62  is fed into the third cylinder  36  until the first and fifth cylinders  10 ′,  62  are butted against each other with no dead volume between. The third cylinder is allowed to cool and it shrinks around the enclosed first and fifth cylinders  10 ,  62  gripping them.  
         [0053]     Heat shrink tubing, to form the fourth cylinder  48 , is cut to a length that will extend from slightly after the fitting nut  94 , along the exposed length of the first column  10 ′, over the third cylinder and a distance comparable to the length of the second cylinder  24  along the fifth cylinder length. This tubing has an inner diameter approximately equal to the outer diameter of the second and third cylinders  10 ′,  62  or slightly larger. It will shrink to half its diameter when heated. The fourth cylinder  48  is threaded from the second end  68  of the fifth cylinder  62  until it is positioned slight before the fitting nut  94  and covers the cylinders. Heat is applied to the fourth cylinder  48  to shrink it. The fourth cylinder deforms gripping the second and third cylinders  24 ,  36  and coming near to the first and fifth cylinders.  
         [0054]     The assembly is easy to put together while achieving a high degree of precision in the placement of the parts. Bandspreading is minimized because the dead volume is controlled. The resultant device is resilient and only requires that the inlet end  18  be connected utilizing the fitting  90  and that the second end  68  of the fifth cylinder  62  be fed to an electro-spray source (for mass spectroscopy) where precision placement is less important.  
         [0055]     One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims.