Analytical device for analyzing a sample

Abstract

Analytical device (1) for the analysis, in particular combustion analysis, of a sample (P), with an analysis channel (3) for the analysis of an analyte (A) of the sample (P) transported through the analysis channel (3) by means of a carrier gas, wherein the analysis channel (3) comprises an analyte detector (4) for detecting the analyte (A) and a gas flow sensor (5) for determining a gas flow in the analysis channel (3), characterized by that the gas flow sensor (5) is arranged downstream of the analyte detector (4), and / or that the analyzer (1) has a reference detector (9) arranged in series with the analyte detector (4) and / or upstream of the analyte detector (4) for carrying out a reference measurement.

Description

The present invention relates to an analysis device according to the preamble of claim 1.Analytical instruments of the generic type are known from the prior art and are used in particular for combustion analysis and / or elemental analysis of organic or inorganic samples. For analysis, an analyte generated from a sample is conducted by means of a carrier gas through an analysis channel and measured or detected there.The analytical instruments known from the prior art or analytical methods carried out therewith, however, have disadvantages.Thus, for example, it has been shown that there is a need for optimization or potential in order to improve the sensitivity of the analytical device or analytical method or to reduce the detection limit.Furthermore, known analytical instruments have a high consumption of carrier gas. Helium or argon is usually used as carrier gas, which is relatively expensive and thus leads to high operating costs.It is an object of the present invention to specify an analytical instrument or a method which is improved with regard to sensitivity during measurement and analysis and / or which is resource-saving, has low gas consumption and / or is distinguished by low operating costs.The above object is achieved by an analysis device according to claim 1.The present invention relates to an analytical instrument for the analysis of a sample. The analytical instrument is designed in particular for carrying out a combustion analysis and / or elemental analysis.The analysis device has an analysis channel for analyzing an analyte of the sample transported through the analysis channel by means of a carrier gas. The analysis channel has an analyte detector for detecting the analyte and a gas flow sensor for determining a gas flow in the analysis channel.According to a first aspect, the gas flow sensor is arranged downstream of the analyte detector. This makes it possible to avoid turbulences upstream of the analyte detector and / or in the area of the analyte detector, or to stabilize the gas flow in the analysis channel upstream of the analyte detector and / or in the area of the analyte detector, which results in a more reliable and / or more accurate measurement as well as a lower detection limit. The sensitivity of the analytical device is thus increased.According to a further aspect, which can also be realized independently, the analysis device has a reference detector, which is arranged in series with the analyte detector and / or upstream of the analyte detector, for carrying out a reference measurement. This makes it possible to dispense with an additional reference channel or a reference channel arranged parallel to the analysis channel, which on the one hand simplifies the construction and makes it more cost-effective. On the other hand, gas can be saved and thus the operation of the analytical device can be made more efficient and less expensive, since the gas used for the reference measurement is used further as carrier gas for the analyte. The reduction in gas consumption is also environmentally friendly and resource-saving. The serial arrangement of analyte detector and reference detector preferably also leads to the same flow velocity prevailing in the analyte detector as in the reference detector, which has an advantageous effect on the measurement or its accuracy and / or detection limit.The analysis channel preferably has at least one control element for controlling and / or stabilizing the gas flow in the analysis channel. The gas flow can thereby be optimized, so that a precise measurement with a low detection limit is possible.The control element is preferably arranged upstream of the analyte detector. This serves to optimize the gas flow upstream of the analyte detector and / or in the region of the analyte detector and preferably results in an improved measurement accuracy, sensitivity and / or detection limit.The analysis channel preferably has a valve, in particular a proportional valve, as the control element or a control element is formed by a valve, in particular a proportional valve. The valve is advantageous for controlling and / or optimizing the pressure and / or the flow velocity in the analysis channel.The analysis channel preferably has a throttle as a control element or a control element is formed by a throttle. The throttle is advantageous for stabilizing the gas flow and / or for reducing a drop in the flow velocity.The analyte detector is preferably a thermal conductivity detector. This enables elemental analysis of the sample.Preferably, the reference detector and the analyte detector are identical in construction. This is conducive to accurate measurement and a low detection limit.It is preferred that the reference detector and the analyte detector are arranged in a common housing or in the same housing or block, respectively. This ensures that the reference detector and the analyte detector are exposed to the same ambient temperatures. This results in an optimum comparison of the measurements carried out with the detectors.The analytical instrument preferably has a feed for feeding the analyte to the analytical channel between the reference detector and the analyte detector. Thus, the reference channel or a reference measurement is preferably integrated into the analysis channel, so that corresponding advantages are achieved.In particular, the analytical device does not have a reference channel parallel to the analysis channel for carrying out a reference measurement. This simplifies the construction of the analytical device considerably and reduces the gas consumption.The analytical instrument preferably has an oven for generating the analyte from the sample, in particular by oxidation or combustion. The analysis device is thereby designed for combustion analysis.According to a further aspect, which can also be realized independently, the present invention relates to a method for the analysis, in particular combustion analysis, of a sample, wherein an analyte of the sample is detected in an analysis channel and a reference measurement is carried out on a gas.According to a first aspect of the method, after carrying out the reference measurement, the gas is used as carrier gas for transporting the analyte through the analysis channel. This allows the quantity of gas required to be reduced and the method can thus be designed to be more cost-effective, environmentally friendly and resource-saving.According to a further aspect of the method, which can also be realized independently, a gas flow measurement is carried out in the analysis channel after the detection of the analyte. Carrying out the gas flow measurement after the detection of the analyte enables an accurate and precise measurement with high sensitivity or a low detection limit.The above-mentioned aspects, features and method steps and further aspects, features and method steps resulting from the claims and the following description can be realized independently of one another and in different combinations.Further advantages, features, properties, aspects and method steps of the present invention are evident from the claims and the following description of preferred embodiments with reference to the drawing.FIGS. 1 and 2 each show an analytical device 1 according to the invention in a schematic or block diagram-like illustration.The analytical device 1 is designed for the analysis, in particular combustion analysis, of a sample P. In particular, the analytical device 1 is designed for elemental analysis, for example for determining the concentration and / or amount of hydrogen, oxygen, nitrogen, carbon and / or sulfur in the sample P.The analytical device 1 preferably has an oven 2 for oxidizing or burning the sample P and / or generating an analyte A of the sample P. The sample P may be an organic or inorganic sample.The analytical device 1 has an analytical channel 3 for the analysis of the sample P or an analyte A of the sample P.In the present invention, analyte A refers in particular to a product generated from sample P, in particular combustion product, which is analyzed or detected by means of the analysis device 1 or in the analysis channel 3. In other words, the sample P itself is not analyzed directly in the analysis device 1, but rather the analyte A is first generated from the sample P, which is then analyzed in the analysis device 1. Preferably, the analyte A has a different chemical composition than the sample P, but permits direct conclusions to be drawn about the chemical composition of the sample P. The analyte A can consist of or comprise various substances, in particular combustion products of the sample P.The analyte A is preferably generated from the sample P in the oven 2. In particular, the analyte A consists of one or more combustion product / s generated / n in the furnace 2 by combustion or oxidation of the sample P.The analyte A is preferably gaseous and / or transportable by means of a carrier gas. The carrier gas is preferably an inert gas or noble gas, in particular helium or argon.In particular, the analyte A is transported through the analysis channel 3 by means of a carrier gas and / or the analysis channel 3 is designed for the analysis or detection of an analyte A transported through the analysis channel 3 by means of a carrier gas.Preferably, the analysis channel 3 has the furnace 2 or the furnace 2 is connected to the analysis channel 3 and / or connected to the analysis channel 3, so that an analyte A generated in the furnace 2 can be transported to the channel 3 or transferred into the analysis channel 3 via an uninterrupted fluidic connection. For example, the analysis channel 3 can pass through the furnace 2 or the analysis channel 3 can be connected to the furnace 2 by means of corresponding lines.The analysis channel 3 has an analyte detector 4 for detecting the analyte A and a gas flow sensor 5 for determining a gas flow in the analysis channel 3. In particular, the gas flow sensor is designed for determining or measuring the volume flow and / or the flow speed in the analysis channel 3.The analyte detector 4 is preferably a thermal conductivity detector.The flow direction of a gas flow in the analysis channel 3 is indicated by arrows in FIG. 1.The gas flow sensor 5 is preferably arranged downstream of the analyte detector 4.It has been shown that the presence of the gas flow sensor 5 leads to turbulence in the analysis channel 3, so that an arrangement of the gas flow sensor 5 upstream of the analyte detector 4, as is customary in the prior art, leads to turbulence of the carrier gas or of the analyte A and thus to a distribution of the analyte A over a larger region, so that no sharp peaks but rather broader distributions of the analyte A are measured with the gas flow sensor 5. Accordingly, the measurement result is inaccurate and small amounts or concentrations of analyte cannot be measured or can be measured only with difficulty. In particular, the sensitivity, detection limit and / or measurement accuracy is therefore improved by the arrangement of the gas flow sensor 5 behind the analyte detector 4, since in this arrangement an at least largely laminar flow prevails before and / or in the region of the analyte detector 4 and / or turbulences occur only after the detection of the analyte A.The analysis channel 3 preferably has at least one control element 6 for controlling and / or stabilizing the gas flow in the analysis channel 3. The analysis channel 3 preferably has a plurality of, in particular different, control elements 6.The control element 6 or the control elements 6 is / are preferably (in each case) arranged upstream of the analyte detector 4.The analytical device 1 or the analytical channel 3 preferably has a valve 6A. The valve 6A is in particular a control element 6. The valve 6A is designed in particular for setting the gas flow.The analytical device 1 or the analytical channel 3 preferably has a throttle 6B. The throttle 6B is in particular a control element 6. the throttle 6B is preferably arranged between the valve 6A and the analyte detector 4. The throttle 6B is designed, in particular, to limit the gas flow in the analysis channel 3 to a defined or definable maximum.The analytical device 1 or the analytical channel 3 preferably has a reduction furnace 7. The reduction furnace 7 is preferably designed for the treatment, in particular reduction, of the analyte A. The term "reduction" is used here in particular in the sense of a chemical reaction in which the analyte A preferably absorbs one or more electrons.In particular, oxygen is taken from the analyte A in the reduction furnace 7, in particular by a corresponding chemical reaction proceeding in the reduction furnace 7.The reduction furnace 7 is preferably arranged upstream of the control element 6 or the control elements 6. The control elements 6 are thus preferably arranged between the reduction furnace 7 and the analyte detector 4.The chemical reaction in the reduction furnace 7 preferably reduces the pressure and / or the flow velocity in the analysis channel 3, in particular upstream of the valve 6A. This change in the flow conditions, in particular the reduction in the pressure and / or the flow speed, is preferably detected by means of the gas flow sensor 5.Preferably, at least one of the control elements 6, in particular the valve 6A, is connected to the gas flow sensor 5 in terms of control technology or regulation technology and / or at least one of the control elements 6, in particular the valve 6A, is controlled on the basis of measurement results of the gas flow sensor 5. In particular, on the basis of the measurement results of the gas flow sensor 5, the valve 6A and / or the throttle 6B can be controlled such that the reduction of the pressure and / or the flow velocity through the reduction furnace 7 is corrected.It can be provided that only the valve 6A is connected to the gas flow sensor 5 in terms of control technology or regulation technology and / or the throttle 6B is not connected to the gas flow sensor 5 in terms of control technology or regulation technology or the throttle 6B is not controlled on the basis of measurement results of the gas flow sensor 5. The throttle 6B is preferably adjusted or adjusted, in particular manually, to a specific flow value, for example approximately 30 l / h. This flow value is preferably not changed.The analytical device 1 or the analytical channel 3 preferably has at least one detection device 8, which is provided in particular in addition to the analyte detector 4. Particularly preferably, the detection device 8 is designed for infrared measurement or detection of the analyte A by means of infrared measurement. In principle, however, other and / or further detection devices 8 are also possible.The detection device 8 is preferably arranged upstream of the reduction furnace 7, the control elements 6, the analyte detector 4 and / or the gas flow sensor 5.The analytical device 1 preferably has a reference detector 9 for carrying out reference measurements. The reference detector 9 is preferably structurally identical to the analyte detector 4.Preferably, a measurement, in particular a measurement of thermal conductivity, is carried out both with the analyte detector 4 and with the reference detector 9. In particular, the carrier gas with the analyte A, in particular its thermal conductivity, is measured with the analyte detector 4, while only the carrier gas or the carrier gas without the analyte A, in particular its thermal conductivity, is measured with the reference detector 9. In particular, the analyte A or its quantity or concentration can be determined from a comparison of the measurements with the analyte detector 4 and the reference detector 9, in particular a difference of the measurement results.The reference detector 9 and the analyte detector 4 are preferably arranged in a common housing 12 and the same housing 12, respectively. This is illustrated schematically in particular in FIG. 2.The housing 12 is preferably a block, in particular a metal block, particularly preferably a stainless steel block. The housing 12 is therefore preferably made at least substantially of massive material and / or metal, in particular stainless steel.The housing 12 or the block preferably has one or more receptacles for the reference detector 9 and the analyte detector 4, in which receptacle or receptacles the reference detector 9 and the analyte detector 4 are received. The receptacle / recesses is / are preferably formed by one or more milled-out portions of the housing 12 or block.By arranging the analyte detector 4 and the reference detector 9 in a common housing or the same housing 12, it is achieved or ensured that the two detectors 4, 9 are exposed to the most identical possible ambient conditions, in particular ambient temperatures. Since the detectors 4, 9 are sensitive to the ambient conditions, the comparison of the measurements carried out with the two detectors 4, 9 is improved as a result.The reference detector 9 is preferably arranged in series with the analyte detector 4 and / or upstream of the analyte detector 4.A serial arrangement of the reference detector 9 and the analyte detector 4 is in particular an arrangement of the reference detector 9 and the analyte detector 4 in the same channel and / or an arrangement such that the gas which passes through the reference detector 9 also passes through the analyte detector 4.The analysis channel 3 preferably has the reference detector 9 or the reference detector 9 is arranged in the analysis channel 3. In other words, a reference channel for carrying out a reference measurement is therefore preferably integrated into the analysis channel 3 and / or arranged serially and / or upstream of the analysis channel 3. In this sense, a section of the analysis channel 3 that has the reference detector 9 therefore preferably represents a reference channel.The gas by means of which the reference measurement is carried out is therefore preferably used further as carrier gas for the analyte A after the reference measurement and / or conducted through the analysis channel 3 and / or to the analyte detector 4.The analysis device 1 thus preferably does not have a reference channel arranged parallel to the analysis channel 3.In contrast, it is common in the prior art that an analysis device has an analysis channel and a reference channel arranged parallel to the analysis channel. In this case, a portion of the gas provided is conducted into the reference channel and used there as gas for carrying out the reference measurement, and another portion of the gas provided is conducted into the analysis channel and used there as carrier gas for transporting the analyte through the analysis channel. In contrast, the analytical device of the present invention is characterized by a lower gas consumption, since the gas for the reference measurement can be used further as carrier gas for transporting the analyte.The aspects of the arrangement of the gas flow sensor 5 downstream of the analyte detector 4 and the arrangement of the reference detector 9 in series with the analyte detector 4 or upstream of the analyte detector 4 cooperate in particular synergistically: the gas flow in the analysis channel 3 or in the region of the analyte detector 4 is optimized by the arrangement of the gas flow sensor 5 downstream of the analyte detector 4. In particular, turbulences before and / or in the area of the analyte detector 4 are avoided, so that the sensitivity is increased or the detection limit decreases. This improvement in the measurement quality in turn makes it possible to dispense with a separate reference channel or a reference channel arranged parallel to the analysis channel 3 and instead to integrate the reference channel or the reference measurement into the analysis channel 3 or to arrange the reference detector upstream of the analyte detector 4, which on the one hand simplifies the construction and on the other hand reduces the gas consumption, since the gas for the reference measurement can be used further as carrier gas for the analyte A. Overall, the construction can thus be simplified and costs both during the production and during the operation of the analysis device 1 can be reduced with a simultaneously improved analysis result.The analytical device 1 preferably has a feed 10 for feeding the analyte A to the analytical channel 3. The supply 10 is preferably arranged downstream of the reference detector 9 and / or between the reference detector 9 and the analyte detector 4 and / or is connected to the analysis channel 3. The feed 10 is preferably arranged upstream of the detection device 8, the reduction furnace 7 and / or the control elements 6.Preferably, the feed 10 is arranged between the furnace 2 and the analysis channel 3 and / or the feed 10 connects the furnace 2 to the analysis channel 3, in particular so that the analyte A generated in the furnace 2 can be fed to the analysis channel 3 via the feed 10.The analytical device 1 preferably has a gas source 11 for providing the carrier gas. The gas source 11 is preferably connected to the analysis channel 3 or the carrier gas can be introduced from the gas source 11 into the analysis channel 3. The gas source 11 is preferably arranged upstream of the reference detector 9 and / or connected to the analysis channel 3.After the analytical device 1 according to the invention has been discussed above in particular, a method according to the invention is explained in more detail below. The method according to the invention is preferably carried out using the analytical instrument 1 described herein. Accordingly, the analytical device 1 is preferably designed to carry out the method steps of the method described herein.The method is a method for analyzing the sample P, in particular for combustion analysis and / or elemental analysis of the sample P.In the method, the analyte A of the sample P is detected in the analysis channel 3, in particular by means of the analyte detector 4.Furthermore, a reference measurement is carried out with a gas, in particular by means of the reference detector 9.Preferably, the gas with which the reference measurement is carried out is (further) used as carrier gas after carrying out the reference measurement for transporting the analyte A through the analysis channel 3. In this way, the gas consumption of the analytical device 1 or method can be significantly reduced and thus the operating costs can be reduced.It is preferred that in the method a gas flow measurement is performed after the detection of the analyte A. This increases the sensitivity of the method or lowers the detection limit for the analyte A.The method sequence is in particular as follows, wherein the steps explained below are carried out in particular in the stated sequence.A gas, in particular an inert gas or noble gas, particularly preferably helium or argon, is provided, in particular by means of the gas source 11.The gas is preferably supplied to the analysis channel 3. In particular, a reference measurement is carried out with the gas, in particular with the reference detector 9. Preferably, the reference measurement is a thermal conductivity measurement in which the thermal conductivity of the gas is determined.After carrying out the reference measurement, the gas is preferably used further as carrier gas for transporting the analyte A or is conducted further through the analysis channel 3.In particular, the gas which is measured in the reference detector 9 and / or is conducted via or through the reference detector 9 is also measured in the analyte detector 9 and / or is conducted via or through the analyte detector 9, in particular together with the analyte A.The sample P is preferably supplied to the furnace 2. The analyte A is preferably generated in the furnace 2 from the sample P, in particular by oxidation or combustion of the sample P. In principle, however, the analyte A can also be generated or provided in another manner.The analyte A is preferably supplied to the analysis channel 3, in particular after the reference measurement or downstream of the reference detector 9 and / or by means of the supply 10.Optionally, further steps for measuring and / or treating the analyte A can take place, in particular a measurement in the detection device 8 and / or a treatment, in particular reduction, in the reduction furnace 7.Preferably, the gas flow of the carrier gas is controlled and / or stabilized with the analyte A, in particular with at least one of the control elements 6 or the control elements 6, particularly preferably with the proportional valve 6A and / or the throttle 6B.The analyte A is preferably detected, in particular with the analyte detector 4. the detection of the analyte A is preferably carried out by a thermal conductivity measurement in which the thermal conductivity of the analyte A or of the carrier gas is measured with the analyte A.In particular, the detection of the analyte A or the determination of the amount and / or concentration of the analyte A is carried out by comparing the measurement results of the measurement carried out with the analyte detector 4 with the measurement results of the reference measurement or the measurement carried out with the reference detector 9.In particular, a difference is formed between the signal or measurement result of the analyte detector 4 and the signal or measurement result of the reference detector 9. By forming the difference, the proportion, in particular the thermal conductivity, of the gas or carrier gas can be calculated from the signal or measurement result of the analyte detector 4.According to one variant, the difference is formed from signals or measurement results that were measured at the same time.According to another variant, the flow velocity in the analysis channel 3 is measured, in particular by means of the gas flow sensor 5, and it is calculated from the flow velocity which time Δt the gas takes to pass from the reference detector 9 to the analyte detector 4. The difference is then formed from the signal or measurement result measured at the time t+Δt using the signal or measurement result measured by the analyte detector 4 and the signal or measurement result measured at the time t using the reference detector 9. In this case, use is made in particular of the fact that the flow speed of the gas in the analysis channel 3 is constant or the gas passes the reference detector 9 and the analyte detector 4 at the same flow speed.Preferably, a gas flow measurement, i.e. in particular a measurement of the flow speed and / or the volume flow in the analysis channel 3, is carried out, in particular with the gas flow sensor 5. The gas flow measurement is preferably carried out after the detection of the analyte A or downstream of the analyte detector 4. At least one or both of the control elements 6, in particular the valve 6A, is / are preferably controlled or regulated on the basis of the values measured with the gas flow sensor 5.In particular, the present invention relates, according to an independently realizable aspect, which can also be combined with the aspects and features explained above, to a method for the analysis, in particular combustion analysis, of a sample P, wherein an analyte A of the sample P is detected in an analysis channel 3, wherein a reference measurement is carried out on a gas, characterized in that the gas is used as a carrier gas for transporting the analyte A through the analysis channel 3 after carrying out the reference measurement, and / or that a gas flow measurement is carried out in the analysis channel 3 after detecting the analyte A.Individual features and aspects of the present invention can be realized independently of one another, but also in any desired combination.List of reference numbers:1 Analytical instrument 2 Oven 3 Analytical channel 4 Analyte detector 5 Gas flow sensor 6 Control element 6A Valve 6B Throttle 7 Reduction oven 8 Detection device 9 Reference detector 10 Feed 11 Gas source 12 Housing A Analyte P Sample

Claims

Analytical device (1) for the analysis, in particular combustion analysis, of a sample (P), having an analysis channel (3) for the analysis of an analyte (A) of the sample (P) transported through the analysis channel (3) by means of a carrier gas, wherein the analysis channel (3) has an analyte detector (4) for the detection of the analyte (A) and a gas flow sensor (5) for the determination of a gas flow in the analysis channel (3), characterized in that the gas flow sensor (5) is arranged downstream of the analyte detector (4), and / or in that the analytical device (1) has a reference detector (9) arranged in series with the analyte detector (4) and / or upstream of the analyte detector (4) for carrying out a reference measurement.Analysis device according to claim 1, characterised in that the analysis channel (3) has at least one control element (6) for controlling and / or stabilizing the gas flow in the analysis channel (3).Analytical device according to claim 2, characterised in that the control element (6) is arranged upstream of the analyte detector (4).Analytical device according to claim 2 or 3, characterised in that the analytical channel (3) has a valve (6A), in particular a proportional valve, as control element (6).Analysis device according to one of Claims 2 to 4, characterized in that the analysis channel (3) has a throttle (6B) as control element (6).Analysis device according to one of the preceding claims, characterized in that the analyte detector (4) is a thermal conductivity detector.Analysis device according to one of the preceding claims, characterized in that the reference detector (9) and the analyte detector (4) are of identical construction.Analysis device according to one of the preceding claims, characterized in that the reference detector (9) and the analyte detector (4) are arranged in a common housing (12).Analytical device according to one of the preceding claims, characterized in that the analytical device (1) has, between the reference detector (9) and the analyte detector (4), a feed (10) for feeding the analyte (A) to the analytical channel (3).Analysis device according to one of the preceding claims, characterized in that the analysis device (1) does not have a reference channel parallel to the analysis channel (3) for carrying out a reference measurement.Analytical device according to one of the preceding claims, characterized in that the analytical device (1) has an oven (2) for generating the analyte (A) from the sample (P), in particular by oxidation or combustion.

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