Device with a connection between two capillaries

Abstract

A device comprising an oven (11) for the thermal treatment of gases, a gas chromatograph (10) or other device for separating gaseous components arranged upstream and / or downstream of the oven (11), and a connection of two capillaries (17, 27; 18, 27) which are provided for conveying an analyte in the gas phase, wherein one of the two capillaries (17, 27; 18, 27) is a reactor tube (27) arranged in the oven (11), and wherein at least one of the capillaries (17, 27; 18, 27) is made of ceramic material or at least partially of quartz glass, characterized in that the two capillaries (17, 27; 18, 27) are permanently and gas-tightly connected to each other by gluing, adhesion or soldering, and that the connection of the two capillaries (17, 27; 18, 27) is resistant to temperatures up to 400°C. or is more heat-resistant.

Description

[0001] The invention relates to a device comprising a furnace for the thermal treatment of gases, a gas chromatograph arranged upstream and / or downstream of the furnace or another device for separating gaseous components, and a connection between two capillaries which are provided for the transmission of an analyte in the gas phase, wherein one of the capillaries is a reactor tube arranged in the furnace and at least one of the capillaries is made of ceramic material or at least partially of quartz glass.

[0002] To measure isotope ratios or gaseous substances, or substances that have been converted into a gas phase, the substances or their components are thermally treated in a reactor, depending on the application, resulting in simple and easily analyzed molecules. These molecules can then be analyzed, for example, using an isotope mass spectrometer.

[0003] A typical reactor is a thin, externally heated tube in which the gas molecules oxidize or otherwise react upon application of heat. The reactor tube is placed in a furnace with an insulating wall or is inserted into the furnace. A gas chromatograph may be positioned upstream of the reactor, which resolves the individual components of a sample over time and gradually feeds them into the reactor tube.

[0004] Alternatively or additionally, a gas chromatograph or a comparable separation device, such as a simple separation column, can be arranged downstream of the reactor. The term "gas chromatograph" has a very broad meaning. The goal is the temporal separation of the components of a sample or reaction products. The corresponding device is preferably heatable.

[0005] Relatively thin lines are provided to guide the gases to and from the reactor tube. For simplicity, these lines and the usually thicker reactor tube are referred to as capillaries and must be connected to each other in a gas-tight and reliable manner to achieve reproducible results. Until now, screw connections between the capillaries have been common practice, particularly where the gases enter and exit the reactor tube. The screw connections are easily removable and allow individual capillaries to be reused while replacing the other, previously connected capillary. A disadvantage of the known screw connections or other removable connections in this area is the high risk of leaks, for example caused by temperature fluctuations or the breakage of the thin tubes during assembly.

[0006] Typical temperature ranges for the operation of gas chromatographs are 20°C to 250°C, sometimes also 20°C to 350°C. The reactors are heated to higher temperatures, namely 500°C or more, preferably even considerably more. To avoid condensate between the gas chromatograph and the reactor, the temperature in this range should not be colder than the highest temperature the gas chromatograph can reach. Consequently, in this application, the connection between the capillary and the reactor must be heat-resistant to at least 250°C, 350°C, 400°C or more. The requirements for heat resistance also depend on the location of the connection point relative to the reactor's heat source and the extent to which the maximum temperature of the reactor influences the temperature of the connection point through heat conduction. In any case, an extremely high heat resistance can be expected.

[0007] Conventional screw connections must meet these extremely high thermal resistance requirements and are correspondingly expensive. The materials used must be carefully selected and their thermal expansion coefficients must be matched to the properties of the capillaries. This is the only way to ensure the required tightness of the connection under high thermal stress. Even the smallest leaks can distort the measurement results. The dreaded fractionation can occur during isotope ratio analysis. In addition, other requirements must be considered, such as avoiding dead volume and condensate formation in the connection area. Both can lead to distorted measurement results.

[0008] It should also be noted that the parts connected to each other, namely the capillary as the supply line to the reactor on the one hand and the reactor capillary on the other, are typically exposed to different temperature fluctuations. In an analysis sequence, the reactor is typically heated first, for example from room temperature to 1000°C. Subsequently, the gas chromatograph, from which the capillary leads directly to the reactor, is regulated or heated over a certain temperature range, for example between 50°C and 300°C. To avoid cooling or condensation, a free space between the oven and the chromatograph is preferably not provided. After the measurement, a connection can be established between the gas chromatograph and another reactor, for example via a switch.The reactor used first then cools down, while the gas chromatograph, and thus also the capillary as the supply line to the reactor, continues to fluctuate between different temperatures or is regulated. This is another reason why the thermal stress in the area of ​​the connection point is considerable. Higher temperatures pose additional problems, as the substances coming from the gas chromatograph can be complex, highly reactive compounds that must not react with the materials used.

[0009] A similar problem arises at the reactor outlet, namely in the area of ​​a connection between the reactor capillary and a capillary for discharging the gases converted or generated in the reactor. The thermal load at the connection point can be somewhat lower in this area if no controlled high temperature is planned downstream. Furthermore, only simple gases usually escape from the reactor.

[0010] US Pat. No. 5,783,741 A discloses a combination of a gas chromatograph, combustion furnace, and isotope mass spectrometer. A capillary tube is provided with a protective sheath. The protective sheath is secured with polyimide resin. The capillary tube is connected to other capillary tubes via suitable connectors.

[0011] WO 89 / 09486 A1 discloses a device comprising a gas chromatograph, a combustion reactor, and an isotope mass spectrometer. Part of the combustion reactor is a quartz capillary into which inlet and outlet lines are inserted.

[0012] The connections between the lines and the capillary are provided with a silver chloride seal. Silver chloride seals can be used up to approximately 300 °C.

[0013] DE 28 52 495 A1 describes a method for joining two metal pipe ends. This involves using a metal connecting sleeve whose inner diameter is slightly smaller than the outer diameter of the pipe ends to be joined. The connecting sleeve is expanded by heating, pushed onto the pipe ends, and then shrinks onto the pipe ends.

[0014] EP 0 519 223 A1 discloses a gas-tight connection between pipes of a compressor refrigerator.

[0015] EP 0 636 882 A1 shows connections between capillary tubes. The ends of the capillary tubes are held in coupling pieces and pressed together under spring pressure.

[0016] DE 20 2005 015 233 U1 discloses a customizable capillary tube system for surface and wall heating systems. Fitting strips or fittings are provided for connecting capillary tubes. The fittings can be designed as push-in fittings or welded or glued to the capillary tubes.

[0017] The object of the present invention is to create a reliable and permanently gas-tight connection between two capillaries, in particular for the application area described above.

[0018] To achieve this object, the device according to the invention is characterized in that the two capillaries are permanently and gas-tightly connected to one another by gluing, adhesion, or soldering, and in that a connection between the two capillaries is heat-resistant up to 400°C or more. The aforementioned connection types can also be combined and result in a gas-tight and non-detachable, permanent connection between the capillaries. When replacing the capillary-like reactor tube, the capillaries connected to it, which are generally thinner, are replaced at the same time. The costs incurred for the thinner capillaries are negligible or are even more than offset by the absence of screw connections. The new solution is not only more reliable than the known solution, but can also be more cost-effective.The connection of the capillaries is carried out and tested by the manufacturer, so that incorrect measurements due to incorrect handling during connection can be ruled out from the outset.

[0019] The invention is not limited to the aforementioned application area. It only concerns the connection of capillaries or capillary-like tubes to one another.

[0020] The selection of a suitable adhesive or adhesion agent depends on the intended application. Expected temperatures, pressures, forces, analyte molecules, and capillary materials must be taken into account.

[0021] The capillaries have at least one metallic or metallized surface for soldering. The reactor capillary is preferably made of a ceramic material, in individual cases of metal. Preferably, a ceramic reactor tube (the reactor capillary) is permanently connected to a capillary made of “Silco-Steel”. The end face and preferably also part of the interior of the reactor capillary can be metallized. The ceramic can be aluminum oxide or aluminum nitride. Aluminum-zirconium oxides or silicon-containing compounds are also possible, or any other type of metallizable ceramic. The metallization should be solderable and able to be applied to the ceramic. A typical metallization consists of tungsten, for example, applied by screen printing and fired, with a layer of nickel on top. If necessary, further or other metal layers can be present, for example a covering layer of gold or possiblyTin if soft soldering is desired.

[0022] Various types of soldering are possible, such as soft soldering or, preferably, hard soldering. Various common silver, copper, and brass solders can be used for this.

[0023] As an alternative to soldering with a metallized capillary, so-called active soldering can be used, in which a suitable solder—typically containing titanium, zirconium, or hafnium—is bonded directly to the ceramic. In this case, two ceramic or other non-metallic capillaries can also be joined together. Typical materials for this include metal (steel, nickel) and ceramic, as well as various temperature-resistant glasses.

[0024] The use of capillaries with inert surfaces, such as the aforementioned Silco-Steel capillaries, is known. Such surfaces can be removed before soldering, for example, by grinding.

[0025] According to a further concept of the invention, the connection has at least one overlap region. This means that, in particular, the interconnected capillaries overlap one another in the axial direction.

[0026] According to a further concept of the invention, the capillaries have different diameters and overlap each other at least at their end regions, with the end regions being connected to each other (in the region of the overlap or part thereof). The different diameters make it possible to push the capillaries to be connected into each other, thus achieving an overlap.

[0027] According to a further concept of the invention, or alternatively, end regions of the capillaries are connected to one another by a connecting piece, wherein the connecting piece overlaps the end regions. The connecting piece also represents a capillary and is only considerably shorter than the capillaries to be connected. The connecting piece can cover the outside of the capillaries to be connected in the manner of a sleeve. Alternatively, the connecting piece can be designed as a capillary-like inner tube and inserted into both end regions of the capillaries to be connected. Finally, depending on the diameter of the capillaries to be connected, the connection can also be designed such that the connecting piece covers one capillary at the end region and enters the end region of the other capillary.

[0028] Advantageously, the capillaries are connected to each other over a large area. This increases the strength and gas-tightness of the connection. "Over a large area" means that the bonding or adhesion is present at more than just a point or line. In particular, "over a large area" refers to an extension in both the axial and circumferential directions.

[0029] At least one of the capillaries can be made of ceramic material. In particular, the capillary-like reactor tube, or at least its inner surface, is made of a ceramic material, e.g., in an H2 reactor. The advantage is at least high heat resistance.

[0030] Preferably, at least one of the capillaries is made at least partially of a metallic material. In particular, an outer surface is metallic. This improves sealability. The connection can also be made by soldering. A metallic inner surface, such as nickel, or so-called glassy carbon is also advantageous due to its smooth and gas-tight surface, as in a CO2 reactor.

[0031] Advantageously, at least one of the capillaries is made at least partially of quartz glass, with an external and / or internal surface, e.g., in an H2 reactor. Synthetic quartz glass or fused silica, also known as fused silica, is particularly suitable. So-called Silco Steel capillaries are also well suited.

[0032] According to a further concept of the invention, a thinner capillary is made of quartz glass and a thicker capillary is made of ceramic material, or a thinner capillary is made of metallic material and a thicker capillary is made of ceramic material. These are two advantageous pairings of capillary materials.

[0033] According to a further concept of the invention, at least one of the capillaries has a coating, and the overlapping area is at least partially devoid of any coating. Fused silica capillaries are known, which are coated on the outside with polyimide. In the overlapping area, this coating is at least partially absent (no longer present). Coatings are conceivable that react at higher temperatures, allowing molecules of the coating to penetrate into the interior of the capillaries under unfavorable conditions. Furthermore, it may be more beneficial for the function of the adhesive or bonding agent if the capillary lacks the otherwise present coating at this location.

[0034] According to a further concept of the invention, the overlapping region has at least one adhesive bond or bonding connection in the area of ​​a coating of one of the capillaries. Adhesives or bonding agents are distributed all around, i.e., circumferentially around, the capillary. In particular, these adhesives or bonding agents are gas-tight. A polyimide-based adhesive, for example, is gas-tight. Different adhesives can also be provided in different temperature zones, e.g., one adhesive for the stability of the bond and one for sealing.

[0035] According to a further concept of the invention, the overlapping area has at least one adhesive bond or adhesion bond in the area outside the coating. Here, too, adhesive or adhesion means are preferably provided all around, with the means used being particularly heat-resistant. "Heat-resistant" in this sense means that the bond remains stable even under the conditions mentioned in the introduction, at temperatures of 400°C or more, e.g., at temperatures of more than 600°C to 800°C, even above 1000°C. A range of 500°C to 1600°C is preferred.

[0036] Advantageously, at least one of the capillaries is made at least partially of precious metal. In particular, this is copper, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold. Sufficient strength for the respective application is important. Non-precious metals can also be used preferentially, e.g., nickel, especially for reactor tubes.

[0037] According to a further concept of the invention, a thinner and a thicker capillary are connected to each other in the overlapping area, the outer diameter of the thinner capillary is greater than or equal to the inner diameter of the thicker capillary - always under the same ambient conditions - and the capillaries are joined together after a thermally induced diameter change of at least one of the capillaries. This results in a firm connection of the capillaries in the overlapping area, subject to radial pressure, in the sense of radial compression. This type of connection can also be implemented using a capillary-like sleeve or inner tube.

[0038] According to a further concept of the invention, it is provided that surfaces lie on top of one another in the overlapping region, namely an inner side and an outer side, that one of the two surfaces is made of a hard material with a defined roughness and the other surface is made of a softer material in comparison, and that the roughness of one surface and the deformability of the material of the other surface are coordinated in such a way that the softer material has penetrated into depressions in the rougher material, thus creating a particularly gas-tight connection. Advantageously, one of the capillaries in the overlapping region is provided with a platinum surface and the other capillary with a ceramic surface, preferably in a CO2 reactor. Of course, the two capillaries can also each be made entirely of platinum or ceramic material.Platinum is relatively soft compared to the ceramic material and, under pressure - by pressing - fills the rough surface of the ceramic material, creating a particularly intimate and gas-tight connection.

[0039] Advantageously, at least one of the capillaries is provided with an inert surface, especially on the inside. A reaction with the flowing gas and / or adhesive is then not to be expected. For example, a capillary with a Silcosteel coating is inertized. Other less reactive surfaces, such as platinum, are also suitable.

[0040] According to a further aspect of the invention, a furnace for the thermal treatment of gases is provided, wherein a reactor tube in the form of a capillary and a heater are arranged in the furnace, and insulation is provided through which the reactor tube and / or a capillary are passed, and wherein the reactor tube and capillary are connected to one another. The reactor tube functions as a capillary and is connected to the (other) capillary in the sense described above. Preferably, the reactor tube is connected to a thinner capillary at each of its two ends.

[0041] According to a further concept of the invention, the capillary connected to the reactor tube has an outer coating, in particular made of a non-heat-resistant material, preferably such as polyimide, wherein the coating is removed as far as the capillary extends from the outside into the insulation. The high temperature existing inside the furnace decreases perpendicular to the insulation to the outside of the same. In order to minimize thermal stress on the coating, it is advantageous to remove the same to the outside of the furnace insulation. In the area of ​​the removed coating, there can also be an overlap between the thinner capillary and the reactor tube. The coating is preferably made of polyimide. A material is assumed to be heat-resistant here if it can withstand temperatures of at least 300°C, preferably even above 400°C, without reacting and / or significantly losing strength.

[0042] Advantageously, the coating ends at a distance from the insulation, especially in an overlap area with the reactor tube. In the worst case, the material of the reactor tube can be highly thermally conductive, or at least more thermally conductive than the insulation. In this case, it is advantageous to provide an area in the axial direction between the insulation and the coating through which heat can be radiated.

[0043] In particular, a gas chromatograph is arranged upstream of the furnace. Additional devices for analysis and / or gas flow can be provided between the furnace and the gas chromatograph. Alternatively or additionally, a gas chromatograph or a simpler separation device can also be arranged downstream of the furnace.

[0044] Advantageously, a mass spectrometer, particularly an isotope mass spectrometer for isotope ratio determination, is arranged downstream of the furnace. Here, too, additional devices for analyzing and / or handling the gases passed through the capillaries can be provided between the furnace and the mass spectrometer.

[0045] Further features of the invention will become apparent from the description and the claims. Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. They show: Fig. 1 is a schematic representation of a device within which a connection of capillaries according to the invention is provided, Fig. 2 a representation of connections according to the invention in the area of ​​a heat-insulating furnace wall, with the alternative solutions a), b), c), d), e) and f), Fig. 3 shows a solder connection between a reactor capillary with metallized ends and a coated metal capillary as a supply line to the reactor or as a discharge line from the reactor.

[0046] During mass spectrometric analysis, substances can be prepared and introduced in various ways. One possibility is the provision of a gaseous sample, for example, in conjunction with a gas chromatograph 10, a downstream combustion furnace 11, a mass spectrometer 12, and an interface 13 for transferring the gaseous substances into an ion source of the mass spectrometer 12. Such an interface 13 is typically referred to as an open split.

[0047] In the gas chromatograph 10, substances contained in a sample are separated from one another over time. Oxidation, reduction, gasification, or pyrolysis takes place in the subsequent furnace 11. The temperatures encountered are significantly higher than the ambient temperature otherwise affecting the apparatus.

[0048] In addition to the aforementioned parts of the apparatus, further components may be provided, which are familiar to the person skilled in the art and need not be described in detail. For example, a cold trap 14 may be provided before reaching the interface 13. Branches 15, 16 may be arranged upstream or downstream of the furnace 11 for specific applications and purposes.

[0049] The gaseous substances are stored within the Fig. The liquid is guided into capillaries 17 and 18 in the apparatus shown in Figure 1. These are made of synthetic quartz glass, also known as fused silica. A composite with other materials is possible. However, capillaries 17 and 18 are preferably made exclusively of synthetic quartz glass with a coating.

[0050] In another embodiment, the capillaries 17, 18 are made of a metallic material, in particular stainless steel, which has a surface coating for the purpose of inerting. Such coatings for steels or stainless steels are known under the name Silcosteel (registered trademark).

[0051] Within the furnace 11, a capillary is also provided, namely a reactor tube, whose ends 19, 20 protrude from the furnace 11. The reactor tube is typically made of a ceramic material and is heated to approximately 800°C to 1600°C, depending on the application. Consumable substances or reactivatable substances can be provided in the reactor tube to promote oxidation, pyrolysis, or other reactions. Thermally assisted reduction of gaseous substances in the furnace 11 is also possible.

[0052] In conventional solutions, capillaries 17 and 18 are connected to each other at their ends 19 and 20 by screw connections. The goal is to allow the reactor tube to be replaced while retaining capillaries 17 and 18. However, these screw connections can be a significant source of error in the analysis. Leaks or dead volumes can occur (especially in the case of assembly difficulties).

[0053] Instead of the known solution, in the present embodiment of the invention, the capillaries 17, 18 are non-releasably connected to each other by their adjacent ends 19, 20, in particular by direct bonding. Known adhesives, particularly high-temperature adhesives, are suitable as adhesives. The adhesives can be selected based on the desired properties, such as the grain size of the filler, temperature resistance, elasticity, thermal expansion, etc.

[0054] A design with two adhesives with different properties is also preferred. A high-temperature adhesive ensures sufficient bond strength. A second adhesive, e.g., with polyimide, increases the seal. The sealing adhesive can also be subsequently injected into the first adhesive.

[0055] Instead of an adhesive bond, a bond can also be provided. Adhesion-enhancing agents can be used. Such agents can also be adhesives.

[0056] Finally, the capillaries 17, 18 can also be connected to the ends 19, 20 by compression. This is particularly possible when using special material pairings, for example with a rough yet hard material on one side and a relatively soft material on the other side. The surface of the softer material is pressed into the surface of the rougher material. The compression can be caused by thermal expansion, for example by strong cooling of the internal capillaries 17, 18 before being inserted into the ends 19, 20 and subsequent expansion of the capillaries 17, 18 depending on the respective ambient temperature. Metallic capillaries, particularly those with a platinum surface, then form a sealing contact from the inside with the ceramic surfaces of the ends 19, 20 of the reactor tube. Other material pairings are possible and can be determined through testing.The joining process can also be reversed. For example, the outer tube can be heated to a high temperature before joining to increase its diameter. After joining, the diameter decreases again depending on the ambient temperature.

[0057] Reactor tube (with the ends 19, 20) and capillaries 17, 18 are thin tubes or lines and are collectively referred to as capillaries in the sense of the invention, but can have different diameters, as is also the case in Fig. 1 and has already been mentioned. It is also possible to connect capillaries of approximately equal thickness using tubular (capillary-like) sleeves that accommodate the ends of the capillaries to be connected. Alternatively, internal capillary pieces can connect the ends of two capillaries.

[0058] Even in the cuff-like connection of capillaries (including the inner capillary tube), a wide variety of materials and joining techniques (adhesive, adhesion, pressing) can be used. Individual examples a) to f) are described in Fig. 2 shown.

[0059] The end 19 of the reactor tube emerges from a heat-insulating wall 21 of the furnace 11, as in Fig. 1, and is made of a ceramic material. The capillary 18 is a fused silica capillary and has a polyimide coating on the outside. In example a), the coated part of the capillary 18 is designated 22. The coating has been removed from one end 23 of the capillary 18 because the coating is not heat-resistant here. The capillary 18 and end 19 are glued to one another twice, namely with an adhesive point 24 between the uncoated end 23 and the end 19. The adhesive point 24 is preferably located inside the furnace 11 and is formed by a high-temperature adhesive. A second adhesive point 25 is formed between the end 19 and the coated part 22 outside the insulation 21. The adhesive may be less heat-resistant here. Preferably, an adhesive is used that is adapted to the properties of the coating, in particular a polyimide adhesive.

[0060] The reactor tube can have a significantly higher thermal conductivity than the insulating wall 21. Heat is then conducted out of the furnace 11 via the ends 19, 20. To reduce the thermal load on the capillary 18 or the coating, the end 19 extends a significant distance beyond the wall 21. Furthermore, the coated part 22 of the capillary 18 extends only a short distance into the end 19, so that the coated part 22 ends before reaching the wall 21. The distance can be several centimeters. In contrast, the uncoated end 23 with the adhesive point 24 can be located inside the furnace 11 or at the level of the insulating wall 21.

[0061] The connection between capillary 17 and end 20 can be designed analogously to the above. However, thermally insensitive materials are preferred for capillary 17 and the corresponding adhesives due to the higher temperatures that may occur after connecting to gas chromatograph 10.

[0062] Due to the described bonding between the capillaries 17, 18 and the ends 19, 20, these connections are reliably and permanently sealed. The reactor tube and capillaries 17, 18 are permanently connected to each other and are replaced together as needed. For this purpose, detachable connections or branches are provided between the capillaries 17, 18 on the one hand and the branches 15, 16 on the other. Such detachable connections are known in principle and need not be explained in detail. Alternatively, the capillaries 17, 18 can also be coupled via detachable connections to the gas chromatograph 10 on the one hand and the cold trap 14 on the other hand, or to other components of the apparatus.

[0063] In example b) the Fig. 2, the capillary 18 has only the adhesive point 25, which is located on the outside relative to the wall 21. A coating may, but need not, be provided. The capillary 18 ends outside the wall 21 at a distance from it, analogous to the coated part 22 in example a).

[0064] When using a highly heat-resistant capillary 18, it can also be guided through the wall 21 into the furnace 11 and terminate there, see example c). Accordingly, the end 19 of the reactor tube inside the furnace 11 does not reach the wall 21. The intended bonding point 24 is highly heat-resistant.

[0065] In example d), as in example a), the capillary 18 has a coated part 22 and an uncoated end 23. Here (example d), however, only the uncoated end 23 extends into the end 19 with a small section of the coated part 22 and ends before reaching the wall 21. The end 23 and the end 19 are bonded in the area of ​​the (single) bonding point 24 with a highly heat-resistant adhesive.

[0066] Example e) shows the connection of capillary 18 to end 19 using a tubular sleeve 26. Preferably, capillary 18 and end 19 are configured with the same outer diameter. Alternatively, sleeve 26 can have different inner diameters at its two ends. Sleeve 26 is glued on both sides to the inner end 18 and 19, respectively, see glue points 24, 25. End 19 extends through wall 21, so that sleeve 26 is arranged outside furnace 11 at a distance from wall 21. Sleeve 26 is made of high-temperature-resistant plastic or other suitable materials.

[0067] Finally, example f) shows a variation of example d)—or, depending on your perspective, also of example a)—namely, with a second adhesive point 25 between the coated part 22 and the end 19, as in example a). However, both adhesive points 24, 25 are located outside the wall 21, analogous to example d).

[0068] Fig. Figure 3 shows a soldered or glued connection between the end 19 or 20 of a reactor capillary 27 on the one hand and a thinner capillary 17 or 18 as a supply line to the reactor or discharge line from the reactor on the other. For the sake of simplicity, reference is made below only to the capillary 17, the end 20, and a soldered connection.

[0069] The capillary 17 is a coated metal capillary, preferably made of steel. An outer coating 28 is removed in the connection area, leaving a metallic core layer 29 exposed. An inner coating 30 can extend to the open end face 31 of the capillary 17. The coatings 28, 30 protect the metallic core layer 29.

[0070] The end 20 or the reactor capillary 27 is made of ceramic material and is provided with a metallic coating 34 at the end, namely in the front region 32 and the adjacent inner region 33. This coating is preferably made of tungsten, nickel, gold, and / or tin, depending on the soldering process.

[0071] The end of the capillary 17 is inserted a short distance into the end 20, creating a short overlap. In the transition area between the end region 32 and the inner region 33, the capillary 17 and the end 20 are permanently connected in a gas-tight or non-detachable manner by a circumferential solder joint 35 (shown in black). This is preferably a hard-soldered connection, for example, with silver or brass solder. However, a soft-soldered connection or an actively soldered connection, for which the metallic coating 34 is not required, or an adhesive bond are also possible. List of reference symbols: 10 Gas chromatograph 11 Oven 12 mass spectrometers 13 Interface 14 cold trap 15 Branching 16 Branching 17 capillaries 18 capillaries 19 End 20 End 21 Wall 22 coated part 23 End without coating 24 adhesive points 25 gluing point 26 cuff 27 Reactor capillary 28 outer coating 29 metallic core layer 30 inner coating 31 front side 32 forehead area 33 Interior 34 metallic coating 35 solder joint

Claims

[1] Device with a furnace (11) for the thermal treatment of gases, a gas chromatograph (10) arranged upstream and / or downstream of the furnace (11) or another device for separating gaseous components, and with a connection of two capillaries (17, 27; 18, 27) which are provided for the transmission of an analyte in the gas phase, wherein one of the two capillaries (17, 27; 18, 27) is a reactor tube (27) arranged in the furnace (11), and wherein at least one of the capillaries (17, 27; 18, 27) consists of ceramic material or at least partially of quartz glass, characterized by that the two capillaries (17, 27; 18, 27) are permanently and gas-tightly connected to one another by gluing, adhesion or soldering, and that the connection between the two capillaries (17, 27; 18, 27) is heat-resistant up to 400° C or more. [2] Device according to claim 1, characterized by that the connection has at least one overlap area. [3] Device according to claim 1 or 2, characterized by that the capillaries (17, 27; 18, 27) have different diameters, overlap each other at least at end regions and the end regions are connected to each other. [4] Device according to claim 1 or any one of the other preceding claims, characterized by that end regions of the capillaries (17, 27; 18, 27) are connected to one another by a connecting piece, in particular a sleeve (26), wherein the connecting piece overlaps the end regions. [5] Device according to claim 1 or any of the other preceding claims, characterized by that the capillaries (17, 27; 18, 27) are connected to each other in a planar manner. [6] Device according to claim 1 or any one of the other preceding claims, characterized by that at least one of the capillaries (17, 27; 18, 27) consists at least partially of metallic material. [7] Device according to claim 1 or any of the other preceding claims, characterized by a thinner capillary (17, 18) made of quartz glass and a thicker capillary (27) made of ceramic material, or a thinner capillary (17, 18) made of metallic material and a thicker capillary (27) made of ceramic material. [8] Device according to claim 2 or any of the other preceding claims, characterized by that at least one of the capillaries (17, 27; 18, 27) has a coating (22), and that in the overlap region there is at least partially no coating. [9] Device according to claim 2 or any one of the other preceding claims, characterized by that the overlapping region has at least one adhesive connection (25) or adhesion connection in the region of a coating of one of the capillaries (17, 27; 18, 27). [10] Device according to claim 8 or 9, characterized bythat the overlapping area has at least one adhesive connection (24) or adhesion connection in the area outside the coating (22). [11] Device according to claim 1 or any of the other preceding claims, characterized by that several different adhesives are used, in particular an adhesive for a solid connection and an adhesive for a gas-tight connection. [12] Device according to claim 6 or any one of the other preceding claims, characterized by that at least one of the capillaries (17, 27; 18, 27) consists at least partially of precious metal. [13] Device according to claim 2 or any of the other preceding claims, characterized bythat a thinner and a thicker capillary (17, 18, 27) are connected to one another in the overlapping region, that the outer diameter of the thinner capillary (17, 18) is larger than the inner diameter of the thicker capillary (27) - in each case under the same ambient conditions - and that the capillaries (17, 27; 18, 27) are joined together after a thermally induced change in diameter of at least one of the capillaries (17, 27; 18, 27). [14] Device according to claim 2 or any one of the other preceding claims, characterized bythat in the overlapping area surfaces lie on top of one another, namely an inside of a capillary (17, 18) and an outside of a capillary (27), and that one of the two surfaces is made of a hard material with a defined roughness and the other surface is made of a softer material, and that the roughness of one surface and the deformability of the material of the other surface are matched to one another in such a way that the softer material has entered into depressions in the rougher material and thus a particularly gas-tight connection exists. [15] Device according to claim 14, characterized by that one of the capillaries (17, 27; 18, 27) has a platinum surface in the overlapping area and the other capillary (17, 27; 18, 27) has a ceramic surface. [16] Device according to claim 1 or any one of the other preceding claims, characterized bythat one or both capillaries (17, 27; 18, 27) consist of nickel or have an inner and / or outer surface provided with nickel. [17] Device according to claim 1 or any of the other preceding claims, characterized by that at least one of the capillaries (17, 27; 18, 27) has an inertized surface, in particular on the inside. [18] Device according to claim 1 or any of the other preceding claims, characterized by that a heater is arranged in the furnace (11) and an insulation is provided through which the reactor tube (27) and / or the further capillary (17, 18) are passed, and wherein the reactor tube (27) and the further capillary (17, 18) are connected to one another. [19] Device according to claim 18, characterized bythat the further capillary has an outer coating (28), in particular made of a non-heat-resistant material such as preferably polyimide, and that the coating (28) is removed as far as the further capillary extends from the outside into the insulation. [20] Device according to claim 19, characterized by that the coating (28) ends at a distance from the insulation, in particular in an overlap area with the reactor tube (27). [21] Device according to claim 1 or any one of the other preceding claims, characterized by that a mass spectrometer (12), in particular an isotope mass spectrometer, is arranged downstream of the furnace (11).

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