Device for determining the content of a chemical element in a sample

Abstract

Device (1) for determining a content of a chemical element in a sample, comprising a combustion device (3), a heating device (4) and a detection unit (5), wherein the heating device (4) has a support tube (6) with a spiral groove (7) in which a heating element (8) is guided.

Description

[0001] The invention relates to a device for determining a content of a chemical element in a sample, comprising a combustion device, a heating device and a detection unit.

[0002] Devices are known in the field of elemental analysis that combust and / or pyrolyze the sample to be analyzed in a combustion tube. The combustion tube is heated by a heater. Pyrolysis takes place under an inert atmosphere, such as argon, whereby the organic components are thermally decomposed. Pure oxygen can also be added to enable complete combustion of the decomposition products. The resulting gases are passed through a drying unit (e.g., membrane dryer) or absorbed into an absorber solution and then fed to the detection unit, where they are analyzed. Among other things, the sulfur, chlorine, nitrogen, and / or carbon content is determined.

[0003] Various heating systems are known in the field of laboratory analysis in which samples are thermally treated in a combustion tube. Heating is typically achieved by a heating coil, which either rests loosely on a smooth ceramic support tube or is embedded in a vacuum-formed insulation.

[0004] When using a support tube, the heating coil is only secured at the ends with clamps or wire loops. The individual coils are held in place by the surrounding insulation, resulting in axial movement of the coils and an uneven temperature profile. Furthermore, assembly is complex and error-prone.

[0005] It is therefore an object of the present invention to provide a device in which a uniform temperature profile is ensured.

[0006] The object is achieved according to the invention by means of claim 1.

[0007] According to the invention, the object is achieved by a device for determining a content of a chemical element in a sample, comprising a combustion device, a heating device and a detection unit, wherein the heating device has a support tube with a spiral groove in which a heating element is guided.

[0008] The support tube thus has a spiral groove into which the heating element is inserted. In particular, the spiral groove is designed to accommodate the heating element in a form-fitting manner. This ensures precise positioning of the heating coil, resulting in a uniform and reproducible temperature profile along the support tube. This significantly improves the analytical accuracy and repeatability of the measurement results.

[0009] In particular, the combustion device serves for the pyrolysis or combustion of the sample. The heating device is designed, in particular, to control the temperature of the combustion device. Optionally, the heating device can have a temperature sensor designed to determine a temperature in the region of the combustion device or in the support tube. The heating device can be designed to regulate the combustion device to a predetermined temperature. This can be done using the temperature sensor. The detection unit is designed, in particular, to determine the content of the chemical element in the sample based on the combustion gases. Chemical elements that can be determined using the device include, for example, sulfur, carbon, chlorine, and / or nitrogen.

[0010] In one embodiment, the combustion device is arranged at least partially in the support tube or in an interior space of the support tube.

[0011] In one embodiment, the combustion device is a combustion tube. The combustion tube can be made of ceramic and / or quartz. The combustion tube can consist of several tubes, some of which are guided inside one another, such as an inner tube and an outer tube that at least partially surrounds the inner tube.

[0012] In one embodiment, the combustion device has a sample holder. The sample is introduced into the combustion device via the sample holder and burned or pyrolyzed there.

[0013] In one design, the support tube is made of ceramic, making it particularly durable.

[0014] In one embodiment, the support tube is embedded in an insulating material. This serves to protect other components of the device from the high temperatures of the heating device.

[0015] In one embodiment, the spiral groove is incorporated into an outer wall of the support tube. This facilitates the insertion of the heating element into the groove.

[0016] In one embodiment, the heating element is a heating coil. The heating coil is an electrically conductive wire with a spiral shape. The heating coil is electrically charged and, due to the electrical resistance, generates heat, which is transferred to the combustion device.

[0017] In one embodiment, the device comprises a transfer unit for transferring the combustion gases to the detection unit. The transfer unit may comprise a fluid line through which the combustion gases are conveyed. Furthermore, the transfer unit may comprise a drying unit for drying the combustion gases, which serves to remove water vapor. Alternatively, the transfer unit may comprise an absorber solution for absorbing the combustion gases in a solution, particularly an aqueous one.

[0018] In one embodiment, the detection unit comprises an ion-selective electrode, a UV fluorescence detector, a chemiluminescence detector, a coulometric electrode unit, and / or an IR detector. An ion-selective electrode (ISE) is an electrochemical sensor that specifically responds to certain ions in a solution and measures their concentration. For this purpose, the combustion gases must be transferred into an aqueous solution. The IR detector analyzes the absorption of specific wavelengths of the combustion gas, which are characteristic of certain molecular vibrations. For example, the concentration of CO2 can be determined via the absorption at approximately 4.26 µm. A chemiluminescence detector is used to measure nitrogen monoxide (NO) and nitrogen dioxide (NO2), the sum of which is referred to as NOx. In particular, the nitrogen oxides react with ozone, emitting light.The UV fluorescence detector utilizes the property of SO2 molecules to fluoresce when excited with UV light. For this purpose, the device can incorporate a UV lamp to excite the combustion gases. The coulometric electrode unit can comprise a working electrode, a counter electrode, and a reference electrode and is used, for example, to determine the chlorine content.

[0019] In the following, the invention will be explained with reference to the following figures Fig. 1-3 are explained in more detail. They show: Fig. 1: an embodiment of the support tube of the device according to the invention. Fig. 2: a design of the support tube with the guided heating element. Fig. 3: an embodiment of the device according to the invention.

[0020] In Fig. Figure 1 shows an embodiment of the support tube 6 of the device 1 according to the invention. The support tube 6 has a spiral or helical groove 7 into which the heating element 8 can be received. The groove 7 is arranged in particular in an outer wall 11 of the support tube 6. The support tube 6 can have an interior space 13 into which the combustion device 3 can be at least partially inserted.

[0021] In Fig. 2 shows an embodiment of the device 1 according to the invention, in which the heating element 8 is introduced into the groove 7. The heating element 8 can be connected to an electronics unit 14, which is designed in particular to electrically supply the heating element 8. The support tube 6 can be surrounded by or embedded in an insulating material 10. The heating element 8 can be operated by means of an electronics unit 14. The combustion device 3 can be at least partially arranged in the support tube 6. Furthermore, the device 1 can have a temperature sensor 17, which is designed to determine a temperature in the support tube 6. The heating device 4 can be designed to set and / or regulate the temperature in the support tube 6 by means of the temperature sensor 17, in particular a temperature measurement value determined by the temperature sensor 17.

[0022] Fig.Figure 3 shows an embodiment of the device 1 according to the invention with a combustion device 3 with an optional sample holder 9, the heating device 4, and a detection unit 5. The sample can be introduced into the combustion unit 3 by means of a sample unit 15. The sample is pyrolyzed or burned in the combustion unit 3 by means of the heating device 4. A gas such as argon, nitrogen, and / or oxygen can be supplied to the combustion unit 3 by means of a gas unit 16. The combustion gases produced during combustion are supplied by means of a transfer unit 12 to a detection unit 5, which analyzes the combustion gases and determines the content of the element to be determined in the sample. List of reference symbols 1 device 3 Combustion device 4 Heating device 5 Detection unit 6 Support tube 7 grooves 8 Heating element 9 Sample collection 10 Insulation material 11 Outer wall 12 transfer unit 13 Interior 14 Electronics unit 15 sample units 16 gas units 17 Temperature sensor

Claims

[1] Device (1) for determining a content of a chemical element in a sample, with a combustion device (3), a heating device (4) and a detection unit (5), wherein the heating device (4) has a support tube (6) with a spiral groove (7) in which a heating element (8) is guided. [2] Device (1) according to claim 1, wherein the combustion device (3) is arranged at least partially in the support tube (6). [3] Device (1) according to one of claims 1-2, wherein the combustion device (3) is a combustion tube. [4] Device (1) according to one of claims 1-3, wherein the combustion device (3) has a sample holder (9). [5] Device (1) according to one of claims 1-4, wherein the support tube (6) is ceramic. [6] Device (1) according to one of claims 1-5, wherein the support tube (6) is embedded in an insulating material (10). [7] Device (1) according to one of claims 1-6, wherein the spiral groove (7) is introduced into an outer wall (11) of the support tube (6). [8] Device (1) according to one of claims 1-7, wherein the heating element (8) is a heating coil. [9] Device (1) according to one of claims 1-8, wherein the device (1) comprises a transfer unit (12) for transferring the combustion gases to the detection unit (5). [10] Device (1) according to one of claims 1-9, wherein the heating device (4) comprises a temperature sensor (17) which is designed to determine a temperature in the support tube (6).

Images