LIQUID JUNCTION ASSEMBLY

Abstract

A liquid junction assembly for providing a flow connection between two tubular conduits. The assembly includes respective bodies configured to define elongated passages of respective first and second cross sections to receive and locate the respective tubular conduits, a plate with at least one hole therethrough of a third cross section smaller than the first and second cross sections, and a seat for the plate, defined in a face of one or both of the bodies. The bodies and the plate are assembled with the plate in the seat and the elongated passages and the hole aligned along a common axis.

Claims

1. A liquid junction assembly for providing a flow connection between two tubular conduits, comprising: respective bodies configured to define elongated passages of respective first and second cross sections to receive and locate the respective tubular conduits; a plate with at least one hole therethrough of a third cross section smaller than said first and second cross sections; and a seat for the plate, defined in a face of one or both of said bodies; wherein the bodies and the plate are assembled with the plate in the seat and the elongated passages and the hole aligned along a common axis.

2. A liquid junction assembly according to claim 1 wherein the respective bodies are discrete bodies.

3. A liquid junction assembly according to claim 1 wherein the respective bodies are portions of a single integral body.

4. A liquid junction assembly according to claim 1 wherein the bodies and the plate are assembled together by one or more of a screw, thread or other mechanical connection between the bodies that traps the plate in the seat between the bodies, welding of the bodies, and adhesive bonding.

5. A liquid junction assembly according to claim 1 wherein the bodies and the plate are assembled together by diffusion bonding at interfaces of the bodies and between opposed faces of the plate and the bodies.

6. A liquid junction assembly according to claim 1 wherein the elongated passages are cylindrical.

7. A liquid junction assembly according to claim 1 where the plate is a disc.

8. A liquid junction assembly according to claim 7 wherein the disc is of a thickness in the range 25-100 μm.

9. A liquid junction assembly according to claim 1 wherein the at least one hole is a series or matrix of holes.

10. A liquid junction assembly according to claim 1 wherein the plate exhibits smooth parallel faces about the hole or holes, and the assembly is configured so that when the conduits are correctly located in the elongated passages, they squarely abut the respective sides of the plate so as to minimize any dead space and to accurately align the inner diameters of the conduits with the hole or holes in the plate.

11. A liquid junction assembly according to claim 1 wherein the elongated passages are of a diameter in the range of 0.5 mm-2 mm and the at least one hole is of a diameter in the range 10 μm-200 μm.

12. A liquid junction assembly according to claim 1 incorporated in a coupling assembly in which respective tubular conduits are located in the elongated passages and securely joined within the liquid junction assembly.

13. A kit for a liquid junction assembly for providing a flow connection between two tubular conduits, comprising: respective bodies configured to define elongated passages of respective first and second cross sections to receive and locate the respective tubular conduits; a plate with at least one hole therethrough of a third cross section smaller than said first and second cross sections; and a seat for the plate, defined in a face of one or both of said bodies; wherein the bodies and the plate are adapted to be assembled with the plate in the seat and the elongated passages and the hole aligned along a common axis.

14. A kit according to claim 13 wherein the respective bodies are discrete bodies.

15. A kit according to claim 13 wherein the respective bodies are portions of a single integral body.

16. A kit according to claim 13 wherein the bodies and the plate are adapted to be assembled together by one or more of a screw, thread or other mechanical connection between the bodies that traps the plate in the seat between the bodies, welding of the bodies, and adhesive bonding.

17. A kit according to claim 13 wherein the bodies and the plate are adapted to be assembled together by diffusion bonding at interfaces of the bodies and between opposed faces of the plate and the bodies.

18. A kit according to claim 13 wherein the elongated passages are cylindrical.

19. A kit according to claim 13 where the plate is a disc, e.g. 25-100 μm thick.

20. A kit according to claim 13 wherein the at least one hole is a series or matrix of holes.

21. A kit according to claim 13 wherein the plate exhibits smooth parallel faces about the hole or holes, and the assembly is configured so that when the conduits are correctly located in the elongated passages, they squarely abut the respective sides of the plate so as to minimize any dead space and to accurately align the inner diameters of the conduits with the hole or holes in the plate.

22. A kit according to claim 13 wherein the elongated passages are of a diameter in the range of 0.5 mm-2 mm and the at least one hole is of a diameter in the range 10 μm-200 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is an exploded perspective view of a liquid junction assembly according to an embodiment of the invention;

[0031] FIG. 2 is a side elevational view corresponding to FIG. 1 but viewed from the other side;

[0032] FIG. 2A is an enlarged cross-sectional view of the disc component;

[0033] FIG. 3 is a perspective view similar to FIG. 1 of the assembled components;

[0034] FIG. 4 is a side elevational view similar to FIG. 2 of the assembled components;

[0035] FIG. 5 is a side elevational view similar to FIG. 2 of a modified embodiment in which the respective body components are adapted for a different coupling system;

[0036] FIG. 6 is a cross-sectional view of the liquid junction assembly of FIG. 1-4 or 5 in situ in a first coupling assembly joining two capillary tubes such as a column to an emitter tip, a tube to an emitter tip, or a column to a tube;

[0037] FIG. 7 is a cross-sectional view of the liquid junction assembly of FIG. 1-4 or 5 in situ in a second coupling assembly joining two capillary tubes such as a column to an emitter tip, a tube to an emitter tip, or a column to a tube;

[0038] FIG. 8 is a cross-sectional view of the liquid junction assembly of FIG. 1-4 or 5 in situ in a third coupling assembly joining two capillary tubes such as a column to an emitter tip, a tube to an emitter tip, or a column to a tube; and

[0039] FIG. 9 is an exploded perspective view similar to FIG. 1 of a further embodiment of the invention for use with multi-lumen tubing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Embodiments of a liquid junction assembly according to the invention are illustrated in FIGS. 1-5 and 9, and their incorporation in coupling assemblies for capillary columns in liquid chromatography and mass spectrometry is depicted in FIGS. 6-8.

[0041] The liquid junction assembly 10 of FIGS. 1-4 includes a pair of generally cylindrical bodies 20, 30 that are of similar configuration and coupled together by engagement of a reduced diameter spigot portion 22 on body 20 with a matching circular recess 32 on body 30. Each body 20, 30 has a main portion 24, 34 of greatest diameter extending from an outer end face 25, 35, joined by an optionally tapered portion 26, 36 to a reduced diameter inner portion 27, 37. In the case of body 20, spigot 22 of further reduced diameter extends from portion 27 to an end face 43 that forms the innermost end of the body, while for body 30 the reduced diameter portion 37 extends to an inner end face 37a of the body, in which recess 32 is formed.

[0042] Extending coaxially through the respective bodies 20, 30 are bores 40, 50 that form elongated passages 41, 51 of respective but in this case equal diameters within reduced diameter portions 27, 37 and respectively open into the end face 43 of spigot 22 and into recess 32. In other embodiments, the diameters of passages 41, 51 may not be equal so as to accommodate tubes or columns of different OD. At their outer ends, the bores 40, 50 are counterbored to provide enlarged threaded sockets 45, 55 for securing the respective bodies to components of a column coupling assembly 100 in the manner depicted in FIG. 8. In this case, the coupling assembly is a pair of SGE SilTite™ ferrule and nut couplings. The middle portion 26 of bore 40, 50 is tapered to accommodate the biconical ferrule 105 of this coupling, as illustrated in FIG. 8.

[0043] Instead of being female threaded sockets, elements 45, 55 could be male threads for use with female nuts.

[0044] The outer ends of main body portions 24, 34 of the bodies includes opposite flats 29, 39 for tool engagement.

[0045] Located or trapped in recess 32 between the end face 43 of spigot 22 and the annular inner face 33 of the seat 32 is a plate, shim or wafer 60 in the form of a circular, in this case metallic, disc. The disc may typically be about 70 μm thick and has been laser drilled with a small central hole 61 sized to match the inner diameter of the capillary columns to be joined by the assembly, or to allow for optimized separation and detection performance. Typical diameters of the hole 61 are 25 or 50 μm for current commercial capillary or nano columns. In this case, disc 60 may typically be of a diameter in the range 1.2 to 2.0 mm.

[0046] In this embodiment, the three components, the bodies 20, 30 and the disc 60, are diffusion welded to form a unitary unit at the interfaces of reduced diameter portions 27, 37 and between the end face 43 of the spigot 22, the disc 60 and the annular inner face 33 of recess 32. In use, the assembly is incorporated as previously described within a coupling assembly 100 such as a SilTite™ coupling (FIG. 8) with respective columns 102, 103 inserted into passages 41, 51 to firmly and squarely abut the disc 60 about the hole 61. To facilitate the seal, the faces of disc 60 are smooth, polished or lapped. One option is to cleave disc 60, if it were made out of glass and depending on its length. The coupling is secured by rotating the nuts 110 (FIG. 8) to clamp the respective biconical ferrule 105 onto the capillary.

[0047] An example of a SilTite™ coupling is disclosed in U.S. Pat. No. 8,128,131, the entire disclosure of which is incorporated herein by reference.

[0048] FIG. 5 depicts an embodiment 10′ similar to that of FIGS. 1-4 except that the tapered portion of the bore 40, 50 is not included. This embodiment is suitable for use with a coupling system such as the nanoViper assembly, as depicted in FIG. 6, or the Matrix assembly.

[0049] In the embodiments illustrated in FIGS. 1-5, the components are diffusion bonded to form a permanent assembly. In an alternative arrangement 10″ (FIG. 7), one body or the other may have a greater diameter and be extended at 90 the inner end to form an internally threaded opening 92 to receive a correspondingly threaded outer surface of the other body. A screwed assembly of this kind is depicted in FIG. 7, again as part of a SilTite™ coupling assembly 100″.

[0050] FIG. 9 depicts a further embodiment 10 for use with multi-lumen tubing. In this embodiment, like parts are indicated by like reference numerals preceded by a “1”. In this case, shim/plate or disc 160 has a square array of four holes 161. Correct alignment of the lumens of the tubing and the holes 161 is achieved by keyed engagements between the plate 160 and the bodies 120, 130, and between the bodies and the tubes. The former of these keys is provided by engaging radial tabs 168, 128 on the plate 160 and on spigot 122, with a matching radial channel (not visible) on recess 132 of reduced diameter inner portion 137. The other key is between a longitudinal groove 148 of semi-circular cross-section along each passage 141, 151, and a rib on the respective tube to rotationally align the tube lumens with holes 161.

[0051] It will be appreciated that the illustrated liquid junction assemblies have significant advantages over prior arrangements. Although multicomponent rather than integral, it may still be provided in a diffusion bonded permanent assembly but the manner in which the hole is provided between the capillary bores is more accurate and simpler. By readily providing good alignment on the axis of the system between the hole and the capillary columns, accidental dead volume is minimized or even potentially eliminated, a valuable advantage in analysis at micro and nano-scales. As depicted in FIGS. 6-8, the liquid junction assembly is readily compatible with a variety of coupling systems.

[0052] Another advantage of this approach to providing a liquid junction is that a variety of combinations of hole diameters, end fittings and ports could be selected from a kit of selectable parts.

[0053] There is complete flexibility in the materials employed to suit different applications. In the principal embodiment described above, the three components are metal so as to permit diffusion bonding. A suitable metal for the disc is 300 or 400 series stainless steel, but titanium would also be suitable. The disc could alternatively be formed in a ceramic, a glass such as borosilicate or quartz, or a polymer such as PEEK or filled PEEK. The components could be all glass. The respective bodies 20, 30 may be made in a conductive material in support of electrospray. For other applications, the bodies 20, 30 and/or the disc 60 might be made of titanium, or of a polymeric material or materials that may or may not be filled with other materials such as conductive fillers to allow for any inert yet conductive connection. Conductivity might be optimized by plating or doping of the disc and/or the bodies or any combination thereof. The assembly could be compatible with ultra-high pressure liquid chromatography and is readily manufacturable as an ultra-low dead volume union in the low nano liter range.

[0054] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.