Gas chromatography device

Abstract

The present invention relates to a gas chromatography device, comprising: - a first thermally controlled enclosure containing a capillary chromatography column wound around an axis, and - a second thermally controlled enclosure containing a detector comprising an inlet adapted to be fluidically connected to one end of the chromatography column, the first enclosure comprising a face through which the end of the chromatography column opens and the second enclosure comprising a face through which the inlet of the detector opens, said device being characterized in that the second enclosure is movable relative to the first enclosure by means of a support, between: - a closed position in which the faces of the first enclosure and the second enclosure are opposite each other with a minimum distance between said faces,and - an open position in which the faces of the first enclosure and the second enclosure are spaced apart from each other so as to form an access space to the fluidic connection between the chromatography column and the detector, the support being arranged so as to keep the second enclosure stable between the closed position and the open position. Figure for abstract: Fig 1,

Description

Title of the invention: Gas chromatography device Technical field

[0001] The present invention relates to a gas chromatography device. State of the art

[0002] A gas chromatography device comprises an injector, at least one separation column (for example a capillary column), and at least one detector. It also comprises elements ensuring the interface between said components.

[0003] Recently, compact analysis devices have been developed that can be transported or easily integrated into existing gas analysis installations. This is particularly due to the development of very compact gas detectors, for example TCD detectors (acronym for the English term "Thermal Conductivity Detector", designating a thermal conductivity detector) and NEMS type detectors (acronym for the English term "Nano ElectroMechanical System", designating a nano-electromechanical system). Such analysis devices are presented for example in documents FR3078164A1 and FR3078165A1.

[0004] A chromatography column makes it possible to separate the species contained in a sample to be analyzed. Such a column can be in the form of a fused silica capillary tube, wound on a coil core.

[0005] The ends of the column are fluidically connected to the injector and the detector. The elements to be connected are very small and often fragile. Furthermore, the capillary tube forming the column does not have any elongation elasticity, which makes its handling delicate.

[0006] The injector, column and detector also require electrical connections to control the temperature of the injector, column and / or detector, as well as to acquire and manage the data to be measured. Cables providing the electrical connection can be cumbersome during handling, and their connection points constitute another fragile element of the device.

[0007] The device is desired to be very compact in order to avoid cold spots and thermal leaks. Consequently, the spaces for managing the interfaces of the various components are restricted, which makes handling difficult.

[0008] In order to facilitate maintenance and use, it is desirable that the device can be used without specific tools or, more advantageously, without tools. Statement of the invention

[0009] An aim of the invention is to design a gas chromatography analysis device that facilitates the handling of fragile elements, while remaining compact and thermally optimized during the execution of the analysis. The assembly must also maintain the mechanical winding tension of the chromatography column.

[0010] For this purpose, the invention proposes a gas chromatography device, comprising:

[0011] - a first thermally controlled enclosure containing a chroma column capillary tography wrapped around an axis, and

[0012] - a second thermally controlled enclosure containing a detector comprising an inlet adapted to be fluidically connected to one end of the chromatography column,

[0013] the first enclosure comprising a face through which the end of the chromatography column opens and the second enclosure comprising a face through which the inlet of the detector opens, said device being characterized in that the second enclosure is movable relative to the first enclosure by means of a support, between:

[0014] - a closed position in which the faces of the first enclosure and the second enclosure are opposite each other with a minimum distance between said faces, and

[0015] - an open position in which the faces of the first enclosure and the second enclosure are spaced apart from each other so as to form an access space to the fluidic connection between the chromatography column and the detector, the support being arranged so as to keep the second enclosure stable between the closed position and the open position.

[0016] By maintaining stable, it is meant in the present text that the second enclosure is maintained in a plane parallel to the path of movement between the closed position and the open position.

[0017] Advantageously, the support comprises a guide means configured to maintain a constant mechanical tension of the chromatography column between the open position and the closed position.

[0018] In some embodiments, the guide means is configured to guide the movement of the second enclosure along a trajectory in the shape of an involute of a circle.

[0019] In other embodiments, the guide means is configured to guide the movement of the second enclosure along a trajectory in the shape of an arc of a circle.

[0020] Preferably, the support is rigidly secured to the first enclosure, the guide means comprising a groove arranged in the support and an axis secured to the second enclosure adapted to slide into said groove.

[0021] Advantageously, the guide means further comprises a linear guide portion adapted to guide the movement of the second enclosure in the closed position in translation in a direction of approaching or moving away from the faces of the first enclosure and the second enclosure.

[0022] Preferably, the gas chromatography device comprises at least one spring positioned between the first enclosure and the second enclosure, such that each spring is compressed in the closed position and relaxed in the open position to apply a constant play-taking force to the second enclosure.

[0023] Advantageously, the support is configured to hold the second enclosure in a plane perpendicular to the axis of the chromatography column.

[0024] In certain embodiments, the device comprises a magnet adapted to hold the second enclosure integral with the support.

[0025] In some embodiments, the device comprises at least one electrical connector secured to the support or the second enclosure, said at least one connector being arranged to contact a contact secured to the first enclosure in the closed position. Preferably, the electrical connector comprises a body and a head mounted on the body by means of an elastic element.

[0026] Finally, the invention also relates to a gas chromatography measuring apparatus, comprising an injector adapted to inject a gaseous sample to be analyzed into the chromatography column and a device as described above, the injector being in fluid connection with the end of the chromatography column opposite the inlet of the detector. Brief description of the figures

[0027] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0028] [Fig.l] is a perspective view of one embodiment of the chromatography device in the open position.

[0029] [Fig.2] is a top view of the embodiment of [Fig.l].

[0030] [Fig. 3] is a perspective view of the embodiment of Figures 1 and 2 in closed position.

[0031] [Fig.4] is a top view of the embodiment of Figures 1-3 in position closed.

[0032] [Fig.5] is a top view of an embodiment in which the guide means comprises a linear portion.

[0033] [Fig.6] is a side view of an embodiment including a compensating spring.

[0034] [Fig.7] is a top view of an embodiment without guiding means in the open position.

[0035] [Fig.8] is a perspective view of the embodiment of [Fig.7] in the closed position.

[0036] [Fig.9] is a perspective view of another embodiment in the open position.

[0037] [Fig. 10] is a perspective view of another embodiment in the open position. Detailed description of embodiments

[0038] Figures 1-10 illustrate different embodiments of a gas chromatography device. Such a cooling device comprises a first thermally controlled enclosure 20, containing a capillary chromatography column 2 wound around an axis in the form of a cylinder, and a second thermally controlled enclosure 30, containing a detector 3 in fluid connection with one end 21 of the chromatography column 2. Advantageously, the second enclosure 30 comprises at least one NEMS detector as described for example in documents FR3078164 and FR3078165 or a TCD detector.

[0039] By "thermally controlled" is meant that each enclosure comprises a temperature regulation unit, said regulation units being configured to vary the temperature in their respective enclosure according to different profiles.

[0040] Typically, an inlet end of the column is fluidically connected to an injector (not shown) adapted to inject into the column a gaseous sample to be analyzed. The outlet end 21 of the column is fluidically connected to the detector 3. At the outlet of the column 2, the species contained in said sample, which have been separated by the column, are successively transferred to the detector 3, said detector 3 being configured to determine, from a physical and / or chemical interaction with each species, the nature of said species.

[0041] The device further comprises a support 4 in which the first enclosure 20 and the second enclosure 30 can be arranged. The first enclosure 20 comprises a face 22 through which the end 21 of the chromatography column opens and the second enclosure 30 comprises a face 32 through which the inlet 33 of the detector opens. The second enclosure 30 is movable relative to the first enclosure 20 between an open position and a closed position, by means of the support 4.

[0042] In the open position, with reference to Figures 1 and 2, the face 22 of the first enclosure 20 and the face 32 of the second enclosure are spaced apart from each other so as to form a space for access to the fluidic connection between the chromatography column and the detector, thus facilitating access to the outlet of the column 2 and to the inlet of detector 3. The open position allows manipulation of the end 21 of column 2 and detector 3, for example to connect column 2 to input 33 of detector 3 or to disconnect column 2 from detector 3 or for any other maintenance operation.

[0043] Typically, the elements to be connected during such a maintenance operation are fragile and of very small dimensions. For example, the column may have an external diameter of approximately 300 μm. The handling of said objects, which may be manual or using tools, therefore requires sufficient space to avoid the risk of damaging the fragile elements.

[0044] In the closed position, with reference to Figures 3 and 4, the face 22 of the first enclosure 20 and the face 32 of the second enclosure 30 are opposite each other with a minimum distance between said faces. The closed position makes it possible to carry out a chromatography analysis in a stable and compact configuration, avoiding mechanical instabilities, thermal leaks and cold spots at the elements connecting the two enclosures 20 and 30.

[0045] The first enclosure 20 is preferably rigidly secured to the support 4. The support 4 is arranged so as to keep the second enclosure 30 stable between the closed position and the open position. Preferably, the support 4 is configured to keep the second enclosure 30 in a plane perpendicular to the winding axis of the chromatography column included in the first enclosure. For example, with reference to Figures 1-4, the second enclosure 30 can be held secured to the support 4 by means of a guide means, comprising for example a groove 51 arranged in the support and an axis 52 secured to the second enclosure 30 adapted to slide in said groove 51.

[0046] The geometry of the guide means is chosen as a function of the shape of the coil on which the chromatography column 2 is wound, so as to ensure that the mechanical tension of the column remains identical in any position of the second enclosure 30 on the guide means.

[0047] Alternatively, the second enclosure 30 may be held integral with the support 4 by means of a magnet which is preferably a permanent magnet. Said magnet may be arranged inside the second enclosure 30. Alternatively, a magnet may be included in the support 4 in the area in which the enclosure 30 is arranged.

[0048] In certain embodiments, with reference to [Fig. 5], the guide means further comprises a linear guide portion adapted to guide the movement of the second enclosure in the closed position in translation in a direction of approaching or moving away from the faces of the first enclosure and the second enclosure. Such a linear guide portion may for example be a groove 53 additional, oriented perpendicular to the face 32 of the second enclosure in the closed position. Thus, a translational movement between the first enclosure 20 and the second enclosure 30 can be carried out in the closed position.

[0049] With reference to Figures 5 and 6, the support may further comprise one or more compensation springs 70 in abutment positioned between the first enclosure and the second enclosure, so that each spring 70 is compressed in the closed position and relaxed in the open position. Such compensation springs 70 make it possible to apply a constant play-compensating force making it possible to maintain the tension of the column constant, and to absorb geometric variations which may appear during assembly due to manufacturing and handling tolerances on the different parts. The springs 70 also make it possible to absorb geometric variations due to the environment, such as for example external vibrations or thermal expansions.

[0050] As illustrated in Figures 7 and 8, the support and the second enclosure may further comprise one or more electrical connectors, a first part 84 of which is arranged in the support 4 and a second part 83 of which is arranged in the second enclosure 30, so as to establish an electrical contact between each first part 84 and each respective second part 83, only in the closed position of the device. Each first part 84 is connected to a source of electrical current, making it possible to power the detector and / or a temperature control unit, and / or to transmit the signal from the detector to a signal processing unit. The second part of one or more connectors, for example in the form of electrically conductive pads, may be mounted on an arm 85 comprising conductive tracks arranged to establish an electrical connection with the detector and / or other elements in the second enclosure 30.

[0051] Such an arrangement of connectors avoids the presence of electrical wires providing an electrical connection between the first enclosure, the second enclosure and the support. It also avoids manual electrical connection operations and excess wire lengths required when handling the enclosures. In an illustrative and non-limiting manner, such electrical connectors may comprise a body and a head mounted on the body by means of an elastic element.

[0052] The transitions between the open position and the closed position will now be described. Starting from the open position, all maintenance operations can be carried out and the end 21 of the column 2 can be connected to the inlet of the detector 33. The enclosure 30 comprising the detector 3 is then moved to the closed position, while maintaining the mechanical tension of the column 2 constant. For this purpose, the movement is carried out in a plane perpendicular to the winding axis of the chromatography column 2 included in the first enclosure 20. In this plane, a tra jectory determined by the winding geometry of the column, to ensure constant maintenance of the mechanical tension in the coil.

[0053] In the case of a column wound in the shape of a cylinder with a circular base, the second enclosure 30 follows a trajectory in the shape of an involute of a circle. It is recalled that an involute of a circle, also called an anti-clothoid (“circle involute” in English), is an involute plane curve, that is to say that its normals are the tangents of the circle.

[0054] In the case of a column wound in the shape of a cylinder with an elliptical base, the second enclosure follows a trajectory in the shape of an arc of a circle.

[0055] A person skilled in the art is able to determine, depending on the geometry of the base of the column, the trajectory adapted to maintain the mechanical tension constant.

[0056] When the support 4 comprises a guide means such as for example a groove 51, the second enclosure 30 is slid into said guide means until it reaches the closed position. The presence of a guide means, such as the groove, makes it possible to guarantee compliance with the required trajectory, whatever the dexterity of the user.

[0057] When the support 4 comprises another means of holding in the plane defined by the winding of the column 2, for example a magnet, the second enclosure 30 held by said means is slid, keeping the mechanical tension of the column 2 constant. In the absence of a guiding means, the user must control the trajectory of the movement, in particular through his experience.

[0058] When the support 4 comprises a guide means comprising a linear guide portion, the second enclosure 20 performs a translational movement in a direction of approaching or moving away from the faces 22 and 32 of the first enclosure 20 and the second enclosure 30. Said translation is possible only when the second enclosure 30 reaches the closed position at the end of its travel. It is therefore possible to carry out a final adjustment to compensate for the various clearances permitted by the assembly, for example the precision of the cutting and winding of the column 2, the length of the connection fittings, and mechanical clearances in the device. When the device comprises a compensation spring 70 in abutment, the spring 70 is compressed in the closed position to apply a constant force to the second enclosure 30.When the device comprises electrical connectors 83, 84, an electrical connection is established between the second part 83 of the connector included in the second enclosure 30 and the first part 84 of the connector included in the support 4.

[0059] The device can then be used to perform one or more gas chromatography analyses.

[0060] Starting from the closed position, a transition can be made to the open position in order to access the connection between the chromatography column and the detector. When the support 4 comprises a guide means comprising a portion of linear guide 53, first a translational movement of the second enclosure towards the first enclosure is carried out and then the axis 52 is slid in the groove 51. The second enclosure 30 is then slid towards the open position, while maintaining constant the mechanical tension of the column. When the support 4 comprises a guide means, the second enclosure 30 is slid in said guide means towards the open position. The movement of the second enclosure 30 follows a trajectory of shape identical to that of the closure, for example an involute shape of a circle when the column is wound according to a cylinder with a circular base, or an arc shape of a circle when the column is wound according to a cylinder with an elliptical base.

[0061] During the transition from one position to the other, the second enclosure 30 is preferably maintained in a plane perpendicular to the winding axis of the chromatography column 2 included in the first enclosure.

[0062] Fig. 9 illustrates an embodiment in which column 2 is wound in an oval shape, comprising two semi-circular portions 91 and two linear portions 92. Elements designated by the same reference signs as in Figs. 1-4 are identical or perform the same function as the elements already described in the first embodiment and will not be described again.

[0063] In this embodiment, the movement of the second enclosure follows a circular arc trajectory.

[0064] [Fig. 10] illustrates another embodiment in which the column is wound in another oval shape, comprising two portions 93 in the form of a segment of a circle of a first radius and two portions 94 in the form of a segment of a circle of a second radius greater than the first radius. In this embodiment, the movement of the second enclosure follows a trajectory in the form of an involute of a circle.

[0065] The invention is not limited to the column geometries shown, but applies to any other geometry on which a column can be wound.

Claims

Claims

1. Gas chromatography device, comprising: - a first thermally controlled enclosure (20) containing a capillary chromatography column (2) wound around an axis, and - a second thermally controlled enclosure (30) containing a detector (3) comprising an inlet adapted to be fluidically connected to one end of the chromatography column (2), the first enclosure (20) comprising a face (22) through which the end of the chromatography column (2) opens and the second enclosure (30) comprising a face (32) through which the inlet of the detector (33) opens, said device being characterized in that the second enclosure (30) is movable relative to the first enclosure (20) by means of a support (4), between: - a closed position in which the faces (22,32) of the first enclosure (30) and the second enclosure (20) are opposite each other with a minimum distance between said faces (22,32), and - an open position in which the faces (22,32) of the first enclosure (20) and the second enclosure (30) are distant from each other so as to form an access space to the fluidic connection between the chromatography column (2) and the detector (3), the support (4) being arranged so as to keep the second enclosure (30) stable between the closed position and the open position,.,

2. Device according to claim 1, wherein the support (4) comprises a guide means configured to maintain a constant mechanical tension of the chromatography column (2) between the open position and the closed position.

3. Device according to claim 2, in which the guide means is configured to guide the movement of the second enclosure (30) along a trajectory in the shape of an involute of a circle.

4. Device according to claim 2, in which the guide means is configured to guide the movement of the second enclosure (30) along a trajectory in the shape of an arc of a circle.

5. Device according to one of claims 2 to 4, in which the support (4) is rigidly secured to the first enclosure (20), the guide means comprising a groove (51) arranged in the support and an axis (52) secured to the second enclosure (30) adapted to slide in said groove (51).

6. Device according to one of claims 2 to 5, in which the guide means further comprises a linear guide portion (53) adapted to guide the movement of the second enclosure in the closed position in translation in a direction of approaching or moving away from the faces of the first enclosure and the second enclosure.

7. Device according to one of the preceding claims, comprising at least one spring (70) positioned between the first enclosure (20) and the second enclosure (30), such that each spring (70) is compressed in the closed position and relaxed in the open position to apply a constant play-taking force on the second enclosure (30).

8. Device according to one of the preceding claims, in which the support (4) is configured to hold the second enclosure (30) in a plane perpendicular to the axis of the chromatography column (2).

9. Device according to one of the preceding claims, comprising a magnet adapted to hold the second enclosure integral with the support (4).

10. Device according to one of the preceding claims comprising at least one electrical connector secured to the support or to the second enclosure, said at least one connector being arranged to contact a contact secured to the first enclosure in the closed position.

11. A device according to claim 10, wherein the electrical connector comprises a body and a head mounted on the body by means of a resilient member.

12. Apparatus for measuring by gas chromatography, comprising an injector adapted to inject a gaseous sample to be analyzed into the chromatography column (2) and a device according to one of the preceding claims, the injector being in fluid connection with the end of the chromatography column (2) opposite the inlet of the detector (3).

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