USE OF A FEEDING DEVICE FOR INTRODUCING SAMPLES INTO A DEVICE

Description

[0001] The present invention relates to a use of a feed device for introducing samples into a device for treating samples, in particular micro samples, for a quantitative elemental analysis with regard to carbon, nitrogen and / or sulfur.

[0002] A CNS isotope analysis system with two separation columns with valve switching is known from the prior art in DE 101 51 646 A1. Furthermore, DE 102 35 662 A1 describes a sample introduction system. All currently known analysis systems for CNS isotope analysis have in common that the simultaneous CN or CNS measurement of very small CNS samples is neither possible sequentially nor simultaneously.

[0003] The article "δ 15< N measurement of organic and inorganic substances by EA-IRMS: a speciation-dependent procedure" by NATACHA GENTILE ET AL, published on October 26, 2012 in ANALYTICAL AND BIOANALYTICAL CHE-MISTRY, Vol. 405, No. 1, pages 159-176, discloses an apparatus and a method for measuring δ 15< N of organic and inorganic substances, in which a sample is immediately converted at approximately 1700°C into gaseous combustion products, which are separated by a PoropaQ gas chromatograph column, and then separated and analyzed in a mass spectrometer.

[0004] Further prior art can be found in the documents DE 20 2004 015247 U1, DE 10 2013 019697 A1, DE 10 2006 015535 A1, FR 2 734 363 A1,

[0005] EP 3 193 165 A1 and US 2016 / 231298 A1 as well as the articles "A measuring system for the fast simultaneous isotope ratio and elemental analysis of carbon, hydrogen, nitrogen and sulfur in food commodities and other biological material" by HANS-PETER SIEPER ET AL, published on 31 July 2006 in RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Vol. 20, No. 17, pages 2521-2527, and "High-temperature elemental analysis and pyrolysis techniques for stable isotope analysis" by Matthias Gehre ET AL, published on 15 July 2003 in Rapid Communications in Mass Spectrometry, Vol. 17, No. 13, pages 1497-1503.

[0006] It is an object of the invention to enable an efficient elemental analysis of C, N and / or S by means of which very small samples can be analyzed.

[0007] This object is achieved by the features of patent claim 1. Further preferred embodiments of the invention are the subject of the dependent claims.

[0008] Aspects of the invention are presented below: A non-claimed device for treating samples, in particular very small samples, for separation in a gas chromatograph for elemental analysis with regard to carbon, nitrogen and / or sulfur, has a first treatment device with an opening, wherein in the first treatment device a sample fed to the first treatment device via the opening can be at least partially evaporated and which is designed to oxidize the at least partially evaporated sample for the first time in a first oxidation region, to reduce it for the first time in a reduction region and to oxidize it a second time in a second oxidation region, wherein the reduction region is arranged between the first and second oxidation regions.

[0009] A second treatment device is connected to the first treatment device and is configured to reduce the sample at least partially evaporated in the first treatment device a second time.

[0010] A feed device (not claimed) for introducing samples, in particular microsamples, into a sample treatment device comprises an inlet opening, via which the feed device can be coupled to a feed device for providing samples, in particular microsamples, and an outlet opening, via which the feed device can be connected to the device. The feed device is configured to guide a sample introduced by means of the feed device via the inlet opening along a longitudinal axis through a heating region, so that the sample is at least partially vaporized upon falling through the feed device before exiting through the outlet opening.

[0011] According to one aspect of the invention, when using a feed device for introducing samples, in particular very small samples, into a device for treating samples, and preferably for at least partially evaporating the samples when introduced into such a device, the feed device is selected from a plurality of feed devices with different diameters and / or different lengths depending on the sample quantity and / or at least one sample property.

[0012] In a method for the quantitative elemental analysis of samples, in particular very small samples, with regard to carbon, nitrogen and / or sulfur, a sample is treated for separation in a gas chromatograph and the thus at least partially evaporated sample is separated in the gas chromatograph into at least two partial gases. A first reference gas is introduced into a mass spectrometer and a first reference signal generated by the mass spectrometer is measured. In addition, a first of the at least two partial gases is introduced from the gas chromatograph into the mass spectrometer and a correspondingly generated first sample signal is measured. Furthermore, a second reference gas is introduced into the mass spectrometer and a correspondingly generated second reference signal generated by the mass spectrometer is measured.Furthermore, a second of the at least two partial gases from the gas chromatograph is introduced into the mass spectrometer, and a correspondingly generated second sample signal is measured. Preferably, a third reference gas is also introduced into the mass spectrometer, and a correspondingly generated third reference signal is measured by the mass spectrometer. In addition, a third of the at least two partial gases from the gas chromatograph is preferably introduced into the mass spectrometer, and a correspondingly generated third sample signal is measured. In addition, the carbon, nitrogen, and / or sulfur content of the sample is determined based on the first and second, preferably also based on the third, reference signals and the first and second, preferably also based on the third, sample signals.

[0013] A system (not claimed) for the quantitative elemental analysis of samples, in particular very small samples, with regard to carbon, nitrogen and / or sulfur, comprises a supply device, in particular with a supply unit, for providing a sample and a device for treating the provided sample, in particular supplied by means of the supply unit. In addition, the system comprises a gas chromatograph for separating the at least partially evaporated sample into at least two partial gases and a gas supply interface for controlling a gas flow of the at least two partial gases from the gas chromatograph and / or of at least two reference gases. A mass spectrometer is configured to output a first and a second reference signal when a first or second reference gas is supplied to the mass spectrometer by means of the gas supply interface, and to output a first and a second sample signal when a first or second reference gas is supplied to the mass spectrometer by means of the gas supply interface.The second of the at least two partial gases is supplied from the gas chromatograph via the gas supply interface. A control device is configured to determine the carbon, nitrogen, and / or sulfur concentration based on the first and second reference signals and the first and second sample signals.

[0014] A microsample within the meaning of the invention is, in particular, a sample containing carbon, nitrogen, and / or sulfur and whose sample weight is between 12 and 120 µg. Preferably, a microsample contains between 2.5 and 14 µg of nitrogen. Preferably, a microsample contains between 10 and 104.5 µg of carbon. Preferably, a microsample contains between 0.2 and 1.5 µg of sulfur.

[0015] Treatment within the meaning of the invention is, in particular, the conversion of a sample, in particular into a sample gas stream, so that, for example, individual, particularly volatile, components of the sample can be separated from one another into partial gases in a gas chromatograph. Treatment can, for example, be the configuration or preparation of the sample for sample gas separation in the gas chromatograph.

[0016] One aspect is based on the approach of passing at least two volatile components of a sample, in particular a very small sample, through a first and a second treatment device and processing them by successive chemical reactions, in particular oxidations and reductions, in such a way that the components, even in the range of a few micrograms, can be separated in a gas chromatograph and an elemental analysis can be carried out on the separated components, i.e. partial gases. The chemical reactions, in particular oxidation and reduction, in the first treatment device take place in several, preferably separate, regions, in particular in a first oxidation region, a reduction region and a second oxidation region.The at least two components of the sample can thus react essentially completely, in particular with reactants arranged in the areas of the first treatment device and the second treatment device. This allows the separation of the at least two components into at least two partial gases in a separation column of the gas chromatograph, with the release of the partial gases from the gas chromatograph or its one separation column for elemental analysis in a mass spectrometer then being possible simply via temperature control.

[0017] For this purpose, the first and / or second treatment device is / are preferably tubular and made of quartz glass. The sample can be at least partially vaporized behind an opening in the first treatment device for introducing the sample, in particular between the opening and the first oxidation region. For this purpose, the device for treating samples preferably has a heating arrangement, for example, a heating wire wound around the tubular treatment device, in particular a high-temperature furnace arranged around the first and second treatment devices.

[0018] The first treatment device is connected to the second treatment device, for example via a glass tube, so that the components of the sample released by the at least partial evaporation of the sample can be reliably fed into the second treatment device after their reaction in the oxidation regions and the reduction region.

[0019] To introduce in particular a small amount of the sample, i.e. a microsample, into the first treatment device through the opening, a feed device is preferably used which can be coupled, for example, to a feed device, in particular an autosampler. The feed device allows precise guidance of the sample quantity provided by the feed device into the first treatment device, in particular by gravity, wherein the sample is at least partially evaporated in a heating region of the feed device before exiting an outlet opening of the feed device. The heating region can be defined, for example, by a heating device of the feed device. Alternatively or additionally, the heating region can also be defined by a heating arrangement of the device for treating samples.In particular, the outlet opening of the feed device can be arranged within the first treatment device, for example below the opening of the first treatment device, when connected to the sample treatment device, in order to enable reliable introduction of samples into the sample treatment device. After introduction into the first treatment device, i.e., in the first treatment device, but still while falling through the feed device, the sample can preferably be at least partially vaporized by the heating arrangement in this way.

[0020] Overall, the disclosure enables particularly efficient elemental analysis of samples.

[0021] In a preferred embodiment, the first oxidation region contains tungsten oxide. This allows for a particularly reliable initial oxidation of the at least partially evaporated sample, in particular of at least two volatile sample components.

[0022] In a further preferred embodiment, the reduction region contains copper wire. The copper wire used here preferably has a particularly high degree of purity, for example, higher than 99%, preferably higher than 99.5%, in particular higher than 99.9%. This allows for a particularly reliable initial reduction of the at least partially evaporated sample, in particular of at least two volatile sample components.

[0023] In a further preferred embodiment, the second oxidation region contains quartz chips or silver-plated cobalt oxide. Quartz chips are preferably used when the at least partially vaporized sample is used to determine the isotope ratios of carbon, nitrogen, and sulfur in a mass spectrometer connected to the gas chromatograph. Alternatively, silver-plated cobalt oxide can be used when the at least partially vaporized sample isotope ratios of carbon and nitrogen are to be determined.

[0024] The quartz chips or the silver-plated cobalt oxide enable complete oxidation of the at least partially evaporated sample in the first treatment device.

[0025] In a further preferred embodiment, the second treatment device contains powdered copper. Alternatively, the copper can also be in the form of fine wires. Filling the second treatment device with the powdered or wire-shaped copper enables complete reduction of the at least partially evaporated sample in the second treatment device.

[0026] In a further preferred embodiment, the first oxidation region is separated from the reduction region and / or the reduction region is separated from the second reduction region by at least one separation region in which quartz wool is arranged. Alternatively or additionally, quartz splinters can also be used. Preferably, the reducing agent for the two-fold reduction in the second treatment device, in particular the copper powder or the copper wires, is also arranged between quartz wool and / or quartz splinters. The separation region(s) can in particular form chemically inert and gas-permeable plugs which reliably position the oxidizing or reducing agents for reaction with the at least partially evaporated sample in the first or second treatment device.

[0027] In a further preferred embodiment, the device, in particular the first treatment device, has a sample catcher arranged between the opening and the first oxidation region, which is designed to receive solid evaporation products, for example ash, of the at least partially evaporated sample. Preferably, the sample catcher is made at least partially from quartz glass and is cup-shaped. The sample catcher can also have quartz wool, which forms a base of the sample catcher. In this case, an outer side of the sample catcher is preferably flush with an inner side of the first treatment device. The solid evaporation products can be reliably collected in this way in order to prevent contamination of the reactants in the oxidation regions and / or the reduction region. At the same time, the at least partially evaporated sample, iethe at least two volatile components of the sample are passed unhindered through the first treatment device.

[0028] In a further preferred embodiment, the device comprises a sample catcher exchange device configured to introduce the sample catcher into the first treatment device via the opening or to remove it from the first treatment device. The sample catcher preferably comprises an engagement, in particular a through-hole, configured to interact with the sample catcher exchange device. For example, a sample catcher exchange device configured as a gripping hook can hook into the engagement arranged on the inside or side of the sample catcher in order to pull the sample catcher, together with any solid evaporation products, out of the first treatment device and reinsert the emptied sample catcher into the first treatment device.This improves the cleaning of the first treatment direction and thus ensures the precision in sample treatment necessary for reliable elemental analysis.

[0029] In a further preferred embodiment, one end of the feed device tapers conically in the region of the outlet opening. The conical shape of the end can be configured such that the end, in particular the outlet opening, of the feed device can be guided at least partially through the opening of the first treatment device, thereby connecting the outlet opening of the feed device to the device for treating samples. The conical shape of the end of the feed device makes it possible, in particular, to guide solid evaporation products of the sample into the sample catcher in a targeted manner. This allows the device for treating samples to operate particularly cleanly.

[0030] In a preferred embodiment, the feed device has a length of between 20 and 120 mm along its longitudinal axis, preferably between 30 and 110 mm, in particular between 40 and 100 mm, and / or a diameter of between 1 and 12 mm, preferably between 2 and 10 mm, in particular between 3 and 8 mm, in the region of the outlet opening. This enables sufficient evaporation of the sample upon falling through the feed device and particularly precise guidance of the solid evaporation products into the sample catcher of the sample treatment device.

[0031] In a further preferred embodiment, the temperature of a separation column of the gas chromatograph is increased to release the second of the at least two partial gases after measuring the first sample signal and reference signal from the gas chromatograph, in particular up to a first predetermined target temperature. Preferably, the temperature is increased according to a first predetermined heating rate and / or maintained at the first predetermined target temperature for a first predetermined period of time, in particular until the second of the at least two partial gases has been passed from the gas chromatograph into the mass spectrometer for analysis.Preferably, after measuring the second sample signal and reference signal, the temperature is further increased, in particular up to a second predetermined target temperature and / or according to a second predetermined heating rate, and / or maintained at the second predetermined target temperature for a second predetermined period of time, in particular until the third of the at least two partial gases has been passed from the gas chromatograph into the mass spectrometer. This allows the determination of isotope ratios of the sample, in particular a very small sample, to be carried out in one go, i.e., with only at least partial evaporation of the sample.

[0032] Further features, advantages, and possible applications of the invention will become apparent from the following description taken in conjunction with the figures, in which the same reference numerals are used throughout for the same or corresponding elements of the invention. They show, at least partially schematically: Fig. 1 shows an example of a system for quantitative elemental analysis of carbon, nitrogen, and / or sulfur; Fig. 2 shows an example of a device for treating samples for quantitative elemental analysis; Fig. 3 shows an example of a feed device with a feed device; Fig. 4 shows an example of a feed device; Fig. 5 shows an example of a sample catcher exchange device; and Fig. 6 shows an example of a method for quantitative elemental analysis.

[0033] In Figure 1an example of a system for the quantitative elemental analysis of carbon, nitrogen and / or sulfur is shown with a feed device 2, a device for treating, in particular converting, samples 3, a dividing device 4, a water trap 5, a gas chromatograph 6, a control device 8, a gas trap 9, gas feed interfaces 10a, 10b, gas reservoirs 11a, 11b, 11c and a mass spectrometer 12, in particular a gas isotope ratio mass spectrometer.

[0034] The sample is fed into the sample treatment device 3 via the feed device 2, for example, a pneumatically controlled autosampler, such as the AS200 type from Fisons. During the feed, the sample is heated and at least partially vaporized, creating a sample gas stream that contains, in particular, at least two volatile components of the sample.

[0035] The treatment of the sample, in particular the at least partially evaporated sample, ie the sample gas stream in the conversion device 3 takes place in a first and a second reaction or treatment device (see Figure 2 ), in particular in two quartz glass tubes of different diameters. During treatment, the at least partially evaporated sample is prepared for gas chromatographic separation in the gas chromatograph 6.

[0036] After processing, a portion of the vaporized sample can be diverted in the splitter device 4. The splitter device 4 can be a manually operated or automated device for dividing the sample gas stream. A portion of the sample gas stream can be discarded or fed to another measuring device (e.g., a secondary detector).

[0037] The water trap 5 preferably has a capillary tube suitable for connection to the splitter device 4 and to the gas chromatograph 6. The water trap 5 is preferably filled with an adsorbent, e.g., phosphorus pentoxide. The adsorbent can be contained, in particular, by quartz wool in the water trap 5, especially in the capillary tube, and prevented from leaking out.

[0038] The sample gases are separated via a single gas chromatographic separation column 7 in the gas chromatograph 6. The separation of the gases is preferably carried out according to a dynamically controlled temperature program, wherein the temperature in the separation column 7, the heating rate and / or the time periods for which a predetermined temperature is maintained are controlled according to the temperature program. The gas chromatograph 6 is preferably controlled by means of a control interface 8c of a control device 8. The temperature program can, for example, be executed by a computer program which is executed by a first control device 8a. The first control device 8a is preferably designed as a computer which activates and controls the sample gas separation in the gas chromatograph 6 via the control interface 8c.

[0039] The separation column 7 is preferably configured to temporally and quantitatively separate the gases N 2 , CO 2 , and SO 2 from the sample gas flow at corresponding target temperatures. Different separation column lengths, inner diameters, and stationary separation column phases are possible to ensure essentially complete separation of the gases.

[0040] The signals for starting the device 3 for converting the sample and for activating the gas trap 9 are preferably transmitted via the control interface 8c. In particular, the signal for starting the device 3 also triggers the start of the chromatographic sample gas separation in the gas chromatograph 6.

[0041] The sample gases are collected in the gas trap 9, which is preferably operated automatically. The gas trap 9 can be operated with liquid nitrogen to cool the gases. Other types of cooling are also possible. Preferably, the gas trap 9 has a cold trap loop, which is formed, for example, by a capillary. The cold trap loop preferably has a length of approximately 50 cm. However, other lengths of the cold trap loop are also possible.

[0042] The sample gases can be fed into the mass spectrometer 12 via the first gas supply interface 10a. The first gas supply interface 10a can be designed, for example, as a pneumatically controlled "open split system," such as the Conflo III from Thermo Fisher Scientific. Alternatively, other gas supply interfaces with comparable functionality are also conceivable.

[0043] The mass spectrometer 12 can, for example, be designed as a gas isotope ratio mass spectrometer, such as the Delta Plus Advantage from Thermo Fisher Scientific. Alternatively, other gas isotope ratio mass spectrometers are also conceivable.

[0044] The mass spectrometer 12 is preferably controlled by a second control device 8b of the control apparatus 8. The second control device 8b is designed, for example, as a computer and is configured to activate and control the mass spectrometer 12 using software.

[0045] For the measurements in the mass spectrometer 12, reference gases, in particular nitrogen, carbon dioxide, and / or sulfur dioxide, can be fed into the mass spectrometer 12 from a corresponding nitrogen reservoir 11a, carbon reservoir 11b, or sulfur reservoir 11c, respectively, via the first gas supply interface 10a or a second gas supply interface 10b. Preferably, the supply of the reference gases is also controlled by the control device 8, in particular the second control device 8b.

[0046] According to the temperature program executed by the first control device 8a, a starting temperature in the gas chromatograph 6 is selected such that the carbon dioxide and sulfur dioxide from the sample gas flow remain in the separation column 7 until a first measurement process for determining nitrogen isotope ratios using the mass spectrometer 12 is completed. Upon initiation of a second measurement process and a predetermined first heating rate until a first target temperature is reached, which is optionally maintained for a predetermined first period of time, the carbon dioxide is then released and carbon isotope ratios are measured. Upon further increasing the temperature by a second predetermined heating rate up to a second target temperature and optionally maintaining the second target temperature for a second predetermined period of time, the sulfur dioxide is then released from the separation column and corresponding sulfur isotope ratios are measured.

[0047] In Figure 2 An example of a device 3 for converting samples is shown. The device has a first reaction device 31 or first treatment device 31 with a first oxidation region 31a, a reduction region 31b, and a second oxidation region 31c, as well as a second reaction device 32 or second treatment device 32.

[0048] The first and second reaction devices 31, 32 are preferably designed as quartz glass tubes. The first reaction device 31 is preferably configured for connection to a supply device, in particular a supply device (not shown). The first and second reaction devices 31, 32 are preferably configured within a heating arrangement, for example, a high-temperature furnace.

[0049] The first treatment device 31 can be filled with reactants for sample oxidation in the first oxidation region 31a and the second oxidation region 31c, or for primary reduction in the reduction region 31b. The preferred oxidizing agent in the first oxidation region 31a is tungsten oxide. Copper wires, especially those with a high degree of purity, are preferably used as the reducing agent. Quartz chips, for example, can be arranged in the second oxidation region 31b, particularly for determining isotopic ratios between carbon, nitrogen, and / or sulfur.

[0050] To determine isotope ratios between carbon and nitrogen, the lower quartz chip filling of the second oxidation region 31c is preferably replaced with silver-plated cobalt oxide.

[0051] The chemicals can ensure rapid and complete sample oxidation, i.e., of the sample gas stream or of the at least two volatile components of the sample. The first oxidation region 31a, the reduction region 31b, and the second oxidation region 31c are preferably separated from one another by separation regions 33. The separation regions 33 can be filled with quartz wool and / or quartz chips.

[0052] The first reaction device 31 has a sample catcher 30, in particular made of quartz glass, which is designed to collect solid evaporation products, in particular ash, remaining during sample evaporation. The sample catcher 30 can, for example, be designed as a tube and sealed with quartz glass wool. Alternatively, the sample catcher 30 can have a sample catcher base 30b that is impermeable to the solid evaporation products. Preferably, the length of the sample catcher 30 and / or the wall thickness of the sample catcher 30 are selected depending on the sample, in particular the sample quantity and / or the sample properties.

[0053] Preferably, the sample catcher 30 has an engagement 30a arranged on the inside or laterally on the sample catcher 30, for example an opening, which allows the exchange of the sample catcher 30 by means of a sample catcher exchange device (see Figure 5 ) is possible.

[0054] The second reaction device 32 is preferably configured for connection to the first reaction device 31 and to a splitter device (not shown). The second reaction device 32 can be filled with fine copper wires for sample reduction. The copper wire filling can be delimited by separation areas 33, in which, for example, quartz glass fragments and / or quartz wool are arranged.

[0055] Preferably, the volume of the second reaction device 32 determines the reduction efficiency of the device 3. A diameter of the second reaction device 32 can be, for example, approximately 4 mm. However, the diameter can also be smaller if necessary.

[0056] Figure 3shows an example of a feed device 2, for example a pneumatically controlled autosampler, such as the AS200 type from FISONS, with a feed device 2a. The feed device 2 is arranged outside a device 3 for treating samples, in particular outside a heating arrangement of the device 3, for example a high-temperature furnace, or can be connected to it.

[0057] The feeding device 2a is designed to feed the sample provided by the feeding device 2, in particular through at least a part of the heating arrangement, for example through a housing wall of the heating arrangement, into a first treatment device (see Figure 2), in particular by utilizing gravity. Preferably, after being provided, the sample falls with the aid of the feed device 2a through one or more heating regions, which are preferably defined by the heating arrangement, so that the sample is heated and evaporates. This creates a sample gas stream, which enters the sample transfer device from the feed device 2a at an end of the feed device 2a opposite the feed device 2.

[0058] Figure 4 shows an example of a feed device 2a with a cylindrical body 20. The feed device 2a has a first end 21a of the body 20, which when using the feed device 2a of a feed device (see Figure 3 ) faces, an inlet opening 22a and an outlet opening 22b at a second end 21b opposite the first end 21a.

[0059] The sample can be introduced, in particular dropped, from the supply device into the feed unit 2a through the inlet opening 22a, so that the sample can be heated and at least partially vaporized by a heating arrangement as it passes through the body 20. The sample gas stream generated in this process, i.e., the at least two volatile components of the sample, can exit through the outlet opening 22b and enter a device for converting samples (see Figure 2).

[0060] The body 20 is preferably made of a stainless steel tube between 40 and 120 mm long and can have an external thread in the region of the first end 21a for screwing into the feed device.

[0061] In the region of the second end 21b, the body 20 tapers conically to the outlet opening 22b. The diameter of the outlet opening 22b is preferably between 3 and 8 mm. The length and diameter of the body 20 must be adapted to the sample transfer conditions.

[0062] Figure 5 shows an example of a sample catcher exchange device 40 for exchanging a sample catcher of a device for transferring samples (see Figure 2 ). The sample finger exchange device 40 has a hook 41 which can be inserted into an engagement, in particular a passage, of the sample catcher, so that the sample catcher can be removed from a first reaction device of the device.

[0063] Figure 6 shows an example of a method 100 for quantitative elemental analysis of carbon, nitrogen and / or sulfur.

[0064] In a first method step S1, a nitrogen reference gas is introduced into a mass spectrometer, in particular via a first gas supply interface, and nitrogen reference signals, so-called "peak centers," are measured. The maximum signal strength is determined depending on the mass spectrometer configuration. Using the reference signals, the signal stability and / or signal sensitivity can be increased in a subsequent measurement of nitrogen isotope ratios with the corresponding mass spectrometer configuration.

[0065] During the first process step S1, a start signal can be issued to a supply device, which then provides a sample and feeds it to a sample treatment device. The sample is at least partially vaporized, generating a sample gas stream. The start signal can also initiate a temperature program for sample gas separation in a gas chromatograph. The converted sample gas stream can then be split into individual sample gas components in a separation column of the gas chromatograph. In particular, carbon dioxide and sulfur dioxide are retained in the separation column.

[0066] Preferably, the start signal is output to the supply device and / or the device for transferring samples via a control interface.

[0067] Nitrogen contained in the sample gas stream is fed to the mass spectrometer via the first gas supply interface and a corresponding isotope ratio is measured, particularly taking into account the nitrogen reference signals.

[0068] In a second process step S2, a carbon reference gas is introduced into the mass spectrometer, in particular via the first gas supply interface, and carbon reference signals are measured. Subsequently, in particular according to the temperature program, the carbon dioxide held in the separation column is released, fed to the mass spectrometer, and a corresponding carbon isotope ratio is measured, in particular taking the carbon reference signals into account. The released carbon dioxide can be diluted with a carrier gas, in particular helium.

[0069] In a third process step S3, a sulfur reference gas is introduced into the mass spectrometer, in particular via a second gas supply interface, and sulfur reference signals are measured. Subsequently, the sulfur dioxide held in the separation column can be released and also introduced into the mass spectrometer, in particular via the first gas supply interface. A sulfur isotope ratio is measured, in particular taking the sulfur reference signals into account.

[0070] If necessary, a gas trap can be activated during each of the three process steps so that parts of the sample gas stream, in particular carbon dioxide or sulfur dioxide unintentionally escaping from the separation column of the gas chromatograph, are retained in the gas trap. List of reference symbols

[0071] 1 System for the quantitative elemental analysis of C, N and / or S 2 Feed device 2a Feed device 3 Sample treatment device 4 Divider device 5 Water trap 6 Gas chromatograph 7 Separation column 8 Control device 8a First control device 8b Second control device 8c Control interface 9 Gas trap 10a First gas supply interface 10b Second gas supply interface 11a Nitrogen reservoir 11b Carbon reservoir 11c Sulfur reservoir 12 Mass spectrometer 20Body 21a, 21first, second end 22a, 22bInlet, outlet opening 30 Sample catcher 30a Inlet 30b Sample catcher base 31 First reaction device 31a First oxidation zone 31b Reduction zone 31c Second oxidation zone 32 Second reaction device 33 Separation zones 40Sample catcher exchange device 41Hook 100Methods for the quantitative elemental analysis of C, N and / or S S1 - S3Procedure steps

Claims

1. Use of a feed device (2a) for introducing samples, in particular very small samples, into an device (1) for treating samples, in particular very small samples, for separation in a gas chromatograph (6) for elemental analysis with respect to carbon, nitrogen and / or sulphur, wherein the device (1) for treating samples comprises - a first treatment device (31) with an opening in which a sample which has been supplied to the first treatment device (31) via the opening can be vaporised, at least in part, and which is set up to oxidise the at least partially vaporised sample in a first oxidation region (31a) for the first time, to reduce it in a reduction region (31b) for the first time, and to oxidise it in a second oxidation region (31c) for a second time, wherein the reduction region (31b) is arranged between the first and second oxidation regions (31a, 31c), and - a second treatment device (32) which is connected to the first treatment device (31) and which is set up to reduce, for a second time, the sample which has been vaporised, at least in part, in the first treatment device (31), wherein the feed device (2a) has an inlet opening (22a), via which the feed device (2a) can be coupled to a feed apparatus (2) for providing samples, in particular very small samples, and an outlet opening (22b) via which the feed device (2a) can be connected to the device (1), and is set up to guide, along a longitudinal axis through a heating region, a sample which has been introduced by means of the feed apparatus (2) via the inlet opening (22a), so that the sample is vaporised, at least in part, as it falls through the feed device (2a) and before exiting through the outlet opening (22b), and wherein the feed device (2a) is selected, as a function of the sample quantity and / or at least one sample property, from a plurality of feed devices with different diameters and / or different lengths.

2. Use of a feed device (2a) according to claim 1, wherein a second end (21b) of the feed device (2a) tapers in the region of the outlet opening (22b).

3. Use of a feed device (2a) according to claim 1 or 2, wherein the feed device (2a) has a length along the longitudinal axis of between 20 mm and 120 mm, preferably between 30 mm and 110 mm, in particular between 40 mm and 100 mm, and / or a diameter in the region of the outlet opening (22b) of between 1 mm and 12 mm, preferably between 2 mm and 10 mm, in particular between 3 mm and 8 mm.