Sample preparation unit for an analyzer for determining the fluorine content of a sample

Abstract

Sample preparation unit (1) for an analyzer (2) for determining the fluorine content of a sample (3), with - a combustion tube (4) with a sample inlet (5), a sample outlet (6) and a water supply opening (20), - a first heating device (8) which is designed to heat the combustion tube (4), - a first storage vessel (9) which contains water, - a first conveying unit (11) which is designed to convey a defined volume of water from the first storage vessel (9) into the water supply opening (20), - a fluid line (10) which fluidically connects the first pumping unit (11) and the water supply opening (20), - a second heating device (12) which is designed to heat the water at least in one end region (10a) of the liquid line (10) facing the water supply opening (20) to a predetermined temperature between 50°C and 99°C such that the water in the liquid line (10) is essentially in a liquid state.

Description

[0001] The invention relates to a sample preparation unit for an analyzer for determining the fluorine content of a sample.

[0002] The fluorine content of a sample can be determined using various analyzers such as ion chromatographs or molecular absorption spectrometers. For this purpose, the samples are first combusted in a sample preparation unit in a stream of oxygen. During combustion in the combustion tube, water is added to the sample to release the fluorine bound within it as hydrogen fluoride. The hydrogen fluoride thus formed is transferred to an aqueous absorber solution, into which it is absorbed, forming fluoride ions. The absorber solution containing the dissolved fluoride ions is then supplied to the analyzer.

[0003] The current method involves adding cold water at ambient temperature to the combustion tube. However, this regularly leads to deflagrations in the combustion tube due to the high temperatures within it. Alternatively, the water can be introduced into the combustion tube in the form of steam. However, the volume of steam cannot be precisely controlled in this case.

[0004] It is therefore an object of the present invention to provide a sample preparation unit with improved water supply.

[0005] The problem is solved according to the invention by claim 1.

[0006] According to the invention, the problem is solved by a sample preparation unit for an analyzer for determining the fluorine content of a sample, with - a combustion tube with a sample inlet, a sample outlet and a water supply opening, - a first heating device designed to heat the combustion tube, - a first storage container which contains water, - a first conveying unit designed to convey a defined volume of water from the first storage vessel into the water supply opening, - a fluid line which fluidically connects the first pumping unit and the water supply opening, - a second heating device designed to heat the water, at least in one end area of ​​the liquid line facing the water supply opening, in particular adjacent to it, to a predetermined temperature between 50°C and 99°C such that the water in the liquid line is essentially in a liquid state.

[0007] According to the invention, heated water is added to the water supply opening. Introducing heated water into the combustion tube prevents a sudden deflagration of the water. Since the heated water is liquid, controlled dosing of the water is also possible. The water is heated, in particular, to a temperature above the ambient temperature of the sample preparation unit, specifically to a temperature between the ambient temperature and the boiling point of water. The fact that the water in the liquid line is essentially in liquid form means, in particular, that no water vapor bubbles form in the liquid line.

[0008] The second heating device can be located at least in the end section of the liquid line. The first heating device surrounds the combustion tube, particularly only partially. The water supply opening is located, in particular, outside the first heating device. The combustion tube can have a capillary on which the water supply opening is located. The water supply opening can be arranged such that the water is added to a region of the sample within the combustion tube.

[0009] In one embodiment, the second heating device is arranged in a jacket of the liquid line. The jacket can partially or completely enclose the liquid line. The second heating device can be arranged along the entire length of the jacket or only in a section of it. The first delivery unit can be a pump, for example, a peristaltic or syringe pump.

[0010] In one embodiment, the second heating device has one or more heating elements. The heating elements can be designed as resistance elements, for example in the form of metallic wires. For example, the heating elements can be arranged in a mesh or spiral pattern around the liquid line.

[0011] In one embodiment, the second heating device includes a temperature sensor configured to determine the temperature in the liquid line. The sample preparation unit can further include a control unit configured to regulate the temperature in the liquid line using the temperature sensor. For example, the control unit can be configured to control the heating power of the second heating device based on the temperature determined by the temperature sensor. In this way, the temperature in the liquid line can be regulated to a predetermined temperature by means of the control unit.

[0012] In one configuration, an ambient pressure of 0.7 to 1.1 bar, particularly essentially 1 bar, is applied to the sample preparation unit. In laboratories, a normal pressure of approximately 1 bar is generally present. However, daily pressure fluctuations can also occur.

[0013] In one embodiment, the second heating device is designed to heat the water, at least in the end region of the liquid line, to a predetermined temperature between 50°C and 99°C at an ambient pressure of 0.7 to 1.1 bar, in particular at 1 bar, such that the water in the liquid line is essentially in a liquid state.

[0014] In one embodiment, the second heating device is designed to heat the water, at least in the end section of the liquid line, to a predetermined temperature between 60°C and 95°C such that the water in the liquid line is essentially in a liquid state. Under these temperature and pressure conditions, the water is heated sufficiently without bubble formation.

[0015] In one embodiment, the second heating device is designed to heat the water, at least in the end region of the liquid line, to a predetermined temperature between 70°C and 90°C such that the water in the liquid line is essentially in a liquid state.

[0016] In one embodiment, the second heating device is configured to heat the water, at least in the end region of the liquid line, to a predetermined temperature between 75°C and 85°C such that the water in the liquid line is essentially in a liquid state. In particular, the predetermined temperature is essentially 80°C.

[0017] In one embodiment, the sample preparation unit includes a condensation unit connected to the sample outlet, designed to condense the sample gases produced during combustion. The condensation unit can be configured as a tube, which is preferably unheated. The condensation unit can be water-cooled or incorporate water cooling. Alternatively, the condensation unit can include Peltier elements.

[0018] In one embodiment, the sample preparation unit includes a mixing unit configured to direct a condensate of the sample gases or the sample gases themselves into an absorber solution. The mixing unit can be configured as a T- or Y-piece. The absorber solution can, for example, consist of an aqueous solution of sodium bicarbonate and potassium permanganate. The absorber solution can also consist solely of water. It is also possible for the absorber solution to consist of an aqueous solution of hydrogen peroxide.

[0019] The mixing unit and the condensation unit can be arranged in series or combined into a single unit. For example, the mixing unit can be connected to the condensation unit in such a way that the sample gases are first introduced into the absorber solution via the mixing unit, and then condensed in the condensation unit and dissolved in the absorber solution. Alternatively, the condensation unit can be connected to the mixing unit in such a way that the sample gases are first condensed in the condensation unit, and the condensate is then introduced into the absorber solution via the mixing unit. It is also possible to combine the mixing unit and the condensation unit so that the condensation of the sample gases and their mixing with the absorber solution occur simultaneously.

[0020] In one embodiment, the sample preparation unit includes a second pumping unit designed to transfer the absorber solution from a second reservoir into the mixing unit. This can be achieved via an additional fluid line that connects the second reservoir to the mixing unit. The second pumping unit can be a pump, such as a peristaltic or syringe pump.

[0021] In one embodiment, the combustion tube has an oxygen supply opening, and the sample preparation unit has a third conveying unit designed to deliver oxygen into the oxygen supply opening. The combustion tube may also have a further capillary on which the oxygen supply opening is located.

[0022] In one embodiment, the sample preparation unit has a fourth conveying unit, which is designed to convey argon into the sample inlet.

[0023] The invention will be further described using the following figures. Fig. 1-4 will be explained in more detail. They show: Fig. 1: a schematic diagram of the sample preparation unit according to the invention. Fig. 2: a design of the combustion tube. Fig. 3: a design of the condensation unit. Fig. 4: one embodiment of the second heating device.

[0024] In Fig. Figure 1 shows a schematic of the sample preparation unit 1. The sample preparation unit 1 can be arranged between a sample introduction unit 24 and an analyzer 2. The sample introduction unit 24 is designed to introduce a sample 3 into the combustion tube 4. The liquid or solid sample can, for example, be introduced into the combustion tube 4 in a quartz glass or ceramic crucible. For this purpose, the sample introduction unit 24 can have an introduction mechanism which, in particular, conveys the sample 3 through the sample inlet 5. The analyzer 2 is used to determine the fluorine content of a sample 3 and is, for example, an ion chromatograph.

[0025] The sample preparation unit 1 comprises a combustion tube 4 and a first heating device 8, which is configured to heat the combustion tube 4, particularly in the region where the sample 3 is located. Specifically, the first heating device 8 is configured to heat the combustion tube 4 such that the sample 3 is combusted within the combustion tube 4. The heating device 8 may partially surround the combustion tube 4, particularly in the region of the combustion tube 4 where the sample 3 is located. The sample preparation unit 1 includes a first storage vessel 9 containing water and a fluid line 10, which fluidically connects the first pumping unit 11 to the water supply opening 20 of the combustion tube 4. A defined volume of water is pumped from the first storage vessel 9 into the water supply opening 20 by means of the first pumping unit 11.

[0026] Furthermore, a second heating device 12 is provided, which is designed to heat the water in at least one end region 10a of the liquid line 10 facing, and in particular adjacent to, the water supply opening 20 to a predetermined temperature such that the water in the liquid line 10 is essentially in a liquid state. The second heating device 12 can be configured as shown by way of example in Fig. The second heating device 12, as shown in Figure 1, is arranged in a sheath 13 of the liquid line 10 and may, for example, comprise several heating elements 14. However, the heating elements 14 can also be attached to the liquid line 10 without the sheath 13. The second heating device 12 can be arranged along the entire length of the liquid line 10 or only in sections of it.

[0027] The sample preparation unit 1 can also include a condensation unit 15, which is connected, in particular fluidically, to the sample outlet 6 of the combustion tube 4. The condensation unit 15 is designed to condense the sample gases produced during the combustion of the sample 3.

[0028] Sample preparation unit 1 can be used, as described in Fig. Figure 3 shows a mixing unit 16, which is designed to direct the condensate or the sample gases 31 into an absorber solution 17. The mixing unit 16 can be configured as a T- or Y-piece such that the condensate or the sample gases 31 are mixed with the absorber solution 17. In the example of the Fig. In the condensation unit 15, the mixing unit 16 is located downstream of the condensation unit 16, such that the mixing unit 16 is arranged between the sample outlet 16 and the condensation unit 15. Alternatively, the condensation unit 15 can surround the mixing unit 16 or be arranged between the sample outlet 6 and the mixing unit 16.

[0029] The absorber solution 17 containing the condensate can then be supplied to the analyzer 2. A second pumping unit 18 can be provided in the sample preparation unit 1 to convey the absorber solution 17 from a second storage vessel 19 into the mixing unit 16. For this purpose, the sample preparation unit 1 can have an additional liquid line 25 that connects the second pumping unit 18 to the mixing unit 16. Optionally, the sample preparation unit 1 can have a waste 22.

[0030] The sample preparation unit 1 can further comprise a third conveying unit 21, which is configured to convey oxygen into an oxygen supply opening 7 of the combustion tube 4. The third conveying unit 21 can be arranged in a gas unit 30, which is further configured to convey argon, for example by means of a fourth conveying unit, into the sample inlet 5. For example, the samples 3 can be introduced into the combustion tube 4 in an argon stream.

[0031] Fig. Figure 2 shows an embodiment of the combustion tube 4 with sample inlet 5 and sample outlet 6. The combustion tube 4 can have an inner tube 27 and an outer tube 26, which at least partially surrounds the inner tube 27. The sample 3 is introduced into the inner tube 27 and combusted there. The sample gases flow through an opening 28 of the inner tube 27 into the outer tube 26 and, particularly after passing through a frit 29, to the sample outlet 6. The sample 3 is often introduced into the combustion tube 4 in an argon atmosphere. During the combustion of the sample 3, oxygen is introduced into the combustion tube 4, at least by means of the oxygen supply opening 7.

[0032] Additionally, a defined volume of water is introduced into the combustion tube 4 via the water supply opening 20. In the example of Fig. 2 Both the water supply opening 20 and the oxygen supply opening 7 are arranged on capillaries connected to the combustion tube 4.

[0033] In Fig. Figure 4 shows an embodiment of the second heating device 12. The second heating device is shown here, by way of example, arranged in a sheath 13 of the liquid line 10. The liquid line 10 can be configured as a hose. The second heating device is wound spirally around the liquid line 10 and can be electrically connected via a connecting line 33. Furthermore, the second heating device 12 can have a temperature sensor 32, which is configured to determine the temperature in the liquid line 10.

[0034] The sample preparation unit 1 can further include a control unit 23, which is designed to control the heating power of the second heating device 12 on the basis of the temperature determined by means of the temperature sensor 32. Reference symbol list 1 Sample preparation unit 2 Analyzers 3 Sample 4 Combustion tube 5 Sample entry 6 Sample outlet 7 Oxygen supply opening 8 first heating device 9 first storage container 10 Liquid line 10a End section of the liquid line 11 first delivery unit 12 second heating device 13 coat 14 Heating element 15 condensation units 16 mixing units 17 Absorbent solution 18 second conveying unit 19 second storage container 20 Water inlet opening 21 third support unit 22 Waste 23 Control unit 24 Sample submission unit 25 more liquid lines 26 outer pipe 27 inner tube 28 Opening 29 Frites 30 gas units 31 Sample gas 32 Temperature sensor 33 Connection cable

Claims

[1] Sample preparation unit (1) for an analyzer (2) for determining the fluorine content of a sample (3), with - a combustion tube (4) with a sample inlet (5), a sample outlet (6) and a water supply opening (20), - a first heating device (8) which is designed to heat the combustion tube (4), - a first storage vessel (9) which contains water, - a first conveying unit (11) which is designed to convey a defined volume of water from the first storage vessel (9) into the water supply opening (20), - a fluid line (10) which fluidically connects the first pumping unit (11) and the water supply opening (20), - a second heating device (12) which is designed to heat the water at least in one end region (10a) of the liquid line (10) facing the water supply opening (20) to a predetermined temperature between 50°C and 99°C such that the water in the liquid line (10) is essentially in a liquid state. [2] Sample preparation unit (1) according to claim 1, wherein the second heating device (12) is arranged in a jacket (13) of the liquid line (10). [3] Sample preparation unit (1) according to one of claims 1-2, wherein the second heating device (12) has one or more heating elements (14). [4] Sample preparation unit (1) according to one of claims 1-3, wherein an ambient pressure of 0.7 to 1.1 bar, in particular of substantially 1 bar, is applied to the sample preparation unit (1). [5] Sample preparation unit (1) according to one of claims 1-4, wherein the second heating device (12) is configured to heat the water at least in an end region (10a) of the liquid line (10) to a predetermined temperature between 50°C and 99°C at an ambient pressure of 0.7 to 1.1 bar, in particular at 1 bar. [6] Sample preparation unit (1) according to one of claims 1-5, wherein the second heating device (12) is configured to heat the water at least in the end region (10a) of the liquid line (10) to a predetermined temperature between 60°C and 95°C [7] Sample preparation unit (1) according to one of claims 1-6, wherein the second heating device (12) is configured to heat the water at least in the end region (10a) of the liquid line (10) to a predetermined temperature between 70°C and 90°C. [8] Sample preparation unit (1) according to one of claims 1-7, wherein the second heating device (12) is configured to heat the water at least in the end region (10a) of the liquid line (10) to a predetermined temperature between 75°C and 85°C, which is 10°C to 1°C below the boiling temperature of the water. [9] Sample preparation unit (1) according to one of claims 1-8, wherein the sample preparation unit (1) has a condensation unit (15) which is connected to the sample outlet (6) and is designed to condense the sample gases (31) produced during the combustion of the sample as condensate. [10] Sample preparation unit (1) according to one of claims 1-9, wherein the sample preparation unit (1) comprises a mixing unit (16) wherein the mixing unit (16) is configured to direct the sample gases (31) or a condensate of the sample gases into an absorber solution (17). [11] Sample preparation unit (1) according to claim 10, wherein the sample preparation unit (1) has a second conveying unit (18) which is configured to convey the absorber solution (17) from a second storage vessel (19) into the mixing unit (16). [12] Sample preparation unit (1) according to one of claims 1-11, wherein the combustion tube (4) has an oxygen supply opening (7) and the sample preparation unit (1) has a third conveying unit (21) which is designed to convey oxygen into the oxygen supply opening (7).

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