METHOD OF OPERATING AN AUTOMATIC ANALYSIS APPARATUS AND AUTOMATIC ANALYSIS APPARATUS

Abstract

The present disclosure relates to a method of operating an automatic analysis apparatus for determining a parameter of a sample liquid which depends on the concentration of an analyte in the sample liquid on the basis of a first measurement variable detected by the analysis apparatus, wherein the analysis apparatus comprises an optical measuring transducer with a measurement unit, the method including: a) providing a reaction mixture comprising the sample liquid in the measurement unit; b) detecting a first measurement variable for determining the parameter; c) detecting a second measurement variable if step b) reveals that the concentration of the analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable; d) diluting the reaction mixture with dilution liquid as a function of the second measurement variable; and e) re-detecting the first measurement variable for determining the parameter.

Claims

1. A method of operating an automatic analysis apparatus for determining a parameter of a sample liquid, which depends on the concentration of at least one analyte in the sample liquid on the basis of a first measurement variable detected by the analysis apparatus, wherein the analysis apparatus comprises a measurement unit including an optical measuring transducer, the method comprising: providing a reaction mixture comprising the sample liquid in the measurement unit; detecting a first measurement variable for determining the parameter using the measurement unit; when the detected first measurement variable indicates that the concentration of the at least one analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable, detecting a second measurement variable of the reaction mixture; diluting the provided reaction mixture with a dilution liquid as a function of the detected second measurement variable; and re-detecting the first measurement variable for determining the parameter in the diluted reaction mixture.

2. The method of claim 1, wherein the first measurement variable includes the extinction, transmission or intensity of light transmitted through the reaction mixture.

3. The method of claim 1, wherein the optical measuring transducer is a photometer or a spectrophotometer.

4. The method of claim 1, wherein the second measurement variable is different from the first measurement variable or is the same measurement variable.

5. The method of claim 1, wherein the detecting of the second measurement variable has a higher measuring uncertainty than the first measurement variable.

6. The method of claim 1, wherein the analysis apparatus includes a dilution unit and a measuring and control electronics, wherein determining the second measurement variable is performed using the optical measuring transducer and the dilution is performed using the dilution unit, wherein the measuring and control electronics determines a dilution factor as a function of the detected second measurement variable and the dilution of the sample liquid is performed by metering using the dilution unit, wherein the dilution unit is controlled by the measuring and control electronics as a function of the dilution factor.

7. The method of claim 1, wherein a volume of dilution liquid supplied to dilute the reaction mixture is determined by a measurement using a measuring device or by specifying a defined metered volume.

8. The method of claim 7, wherein the volume of dilution liquid supplied is taken into account when determining the concentration of the at least one analyte in undiluted sample liquid.

9. The method of claim 1, wherein the analysis apparatus includes an interface with a sampling point, wherein the sample taken from the sampling point corresponds to the sample liquid introduced into the measurement unit.

10. The method of claim 1, further comprising: flushing at least the measurement unit of the analysis apparatus with a first volume of the sample liquid; discharging the first volume of the sample liquid used to flush the measurement unit into a collection container containing a waste liquid mixture; introducing a second volume of the sample liquid into the measurement unit as the provided sample liquid of the reaction mixture; producing the reaction mixture from at least a portion of the second volume of sample liquid and at least one reagent; detecting a measured value to detect a first measurement variable of the reaction mixture in the measurement unit, wherein the measurement variable correlates with the parameter of the sample liquid that is to be determined; and after detecting the measured value, discharging the reaction mixture from the measurement unit into the collection container.

11. The method of claim 1, wherein the dilution liquid is essentially free of the at least one analyte.

12. A method of operating an automatic analysis apparatus for determining a parameter of a sample liquid, which depends on the concentration of at least one analyte in the sample liquid on the basis of a first measurement variable detected by the analysis apparatus, wherein the analysis apparatus comprises a measurement unit including an optical measuring transducer, the method comprising: providing a reaction mixture comprising the sample liquid in the measurement unit; detecting a first measurement variable for determining the parameter; when the detected first measurement variable indicates that the concentration of the at least one analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable, introducing a predefined volume of a dilution liquid to the reaction mixture; re-detecting the first measurement variable for determining the parameter in the diluted reaction mixture; and when the re-detected first measurement variable indicates that the concentration of the at least one analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable, repeating the introducing of the predefined volume of a dilution liquid and the re-detecting the first measurement variable.

13. The method of claim 12, wherein the first measurement variable includes the extinction, transmission or intensity of light transmitted through the reaction mixture.

14. The method of claim 12, wherein the optical measuring transducer is a photometer or a spectrophotometer.

15. The method of claim 12, wherein the second measurement variable is different from the first measurement variable or is the same measurement variable.

16. The method of claim 12, wherein the detecting of the second measurement variable has a higher measuring uncertainty than the first measurement variable.

17. The method of claim 12, wherein the analysis apparatus includes a dilution unit and a measuring and control electronics, wherein determining the second measurement variable is performed using the optical measuring transducer and the dilution is performed using the dilution unit, wherein the measuring and control electronics determines a dilution factor as a function of the detected second measurement variable and the dilution of the sample liquid is performed by metering using the dilution unit, wherein the dilution unit is controlled by the measuring and control electronics as a function of the dilution factor.

18. The method of claim 12, wherein a volume of dilution liquid supplied to dilute the reaction mixture is determined by a measurement using a measuring device or by specifying a defined metered volume.

19. The method of claim 18, wherein the volume of dilution liquid supplied is taken into account when determining the concentration of the at least one analyte in undiluted sample liquid.

20. The method of claim 12, wherein the analysis apparatus includes an interface with a sampling point, wherein the sample taken from the sampling point corresponds to the sample liquid introduced into the measurement unit.

21. The method of claim 12, further comprising: flushing at least the measurement unit of the analysis apparatus with a first volume of the sample liquid; discharging the first volume of the sample liquid used to flush the measurement unit into a collection container containing a waste liquid mixture; introducing a second volume of the sample liquid into the measurement unit as the provided sample liquid of the reaction mixture; producing the reaction mixture from at least a portion of the second volume of sample liquid and at least one reagent; detecting a measured value to detect a first measurement variable of the reaction mixture in the measurement unit, wherein the measurement variable correlates with the parameter of the sample liquid that is to be determined; and after detecting the measured value, discharging the reaction mixture from the measurement unit into the collection container.

22. The method of claim 12, wherein the dilution liquid is essentially free of the at least one analyte.

23. An automatic analysis apparatus for determining measured values of a parameter dependent on the concentration of at least one analyte in a sample liquid, the analysis apparatus comprising: an optical measuring transducer including a measurement unit; a sample liquid line fluidically connected with a sampling point containing the sample liquid; a dilution unit fluidically connected with the measurement unit and a supply line for dilution liquid, the dilution unit configured to dilute a reaction mixture introduced into the measurement unit with the dilution liquid; at least one liquid container containing a reagent; and means for transporting the sample liquid and the reagent to the measurement unit and for producing a reaction mixture from the diluted sample liquid and the reagent, wherein the measurement unit is adapted to generate a measurement signal representing a first measurement variable and/or a second measurement variable of the reaction mixture, such measurement variable correlating with the parameter to be determined; and a measuring and control unit configured to perform operations including: providing the reaction mixture comprising the sample liquid in the measurement unit; detecting the first measurement variable for determining the parameter using the measurement unit; when the detected first measurement variable indicates that the concentration of the at least one analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable, detecting a second measurement variable and diluting the provided reaction mixture with a dilution liquid as a function of the detected second measurement variable; and/or when the detected first measurement variable indicates that the concentration of the at least one analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable, introducing a predefined volume of a dilution liquid into the reaction mixture; re-detecting the first measurement variable for determining the parameter in the diluted reaction mixture; and when the re-detected first measurement variable indicates that the concentration of the at least one analyte in the reaction mixture is outside the measuring range of the analysis apparatus for detecting the first measurement variable, repeating the introducing of the predefined volume of a dilution liquid and the re-detecting the first measurement variable.

24. The analysis apparatus of claim 23, further comprising a collection container arranged downstream of the measurement unit and containing a waste liquid mixture.

25. The analysis apparatus of claim 23, wherein the measurement unit includes a measuring cell or a measuring cuvette, wherein a volume of the measuring cell or measuring cuvette is matched to the method performed.

26. The analysis apparatus of claim 23, wherein the measurement unit includes a measuring cell or a measuring cuvette, wherein the measuring cell or measuring cuvette includes an open drain configured to define a maximum liquid level.

27. The analysis apparatus of claim 23, wherein the measurement unit includes a measuring cell or a measuring cuvette, wherein the measuring cell or measuring cuvette includes an overflow weir adapted to define a maximum liquid level.

28. The analysis apparatus of claim 23, wherein the measurement unit includes a measuring cell or a measuring cuvette, wherein a stirring element of a magnetic stirrer is disposed in the measuring cell or measuring cuvette.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The present disclosure is described in more detail in the following with reference to the exemplary embodiments illustrated in the figures. The following are shown:

[0090] FIG. 1 shows an automatic analysis apparatus for determining a concentration-dependent parameter;

[0091] FIG. 2 shows a schematic representation of a first measuring cell for integration into an analysis apparatus according to FIG. 1;

[0092] FIG. 3 shows a schematic representation of a second measuring cell for integration into an analysis apparatus according to FIG. 1; and

[0093] FIG. 4 shows a schematic representation of a third measuring cell for integration into an analysis apparatus according to FIG. 1.

DETAILED DESCRIPTION

[0094] FIG. 1 schematically shows an automatic analysis apparatus 1, as, inter alia, also described in application DE 10 2018 131 060.9, with a measurement unit 2 and a dilution unit 3, upstream of the measurement unit 2, for diluting a sample liquid taken from a sampling point via the sample line 4. Further details regarding individual components of the analysis apparatus can be taken from the aforementioned application.

[0095] Optionally, the sample line 4 can have a branch 5, with which the sample taken can be transferred via a second sample line into the dilution unit 3. The dilution unit 3 is only optional and can also advantageously be saved when carrying out the method according to the present disclosure, since a pre-dilution is now no longer absolutely necessary.

[0096] The dilution unit 3 is connected via a further liquid line 6 with the measurement unit 2, which serves to supply diluted sample liquid to the measurement unit 2.

[0097] The sampling point may be, for example, an open body of water, a basin of a water treatment or clarification plant, or a process container of a process engineering process. The measurement unit 2 serves to determine values of a parameter that depends on the concentration of at least one analyte contained in the sample liquid. The parameter may, for example, be a concentration of a single analyte, for example an ion type, an organic substance or another dissolved substance. The parameter may also be a sum parameter to the value of which a plurality of analytes contributes, for example the spectral absorption coefficient SAC, total nitrogen content TN, chemical oxygen demand CSB or COD, or total carbon content (TC).

[0098] In the present example, the sample liquid is a water-based solution or mixture (for example, suspension, dispersion and/or emulsion, solution). However, the device described herein and the method described further below can also be used for dilution and analysis of sample liquids based on solvents other than water.

[0099] In the present example, the measurement unit 2 comprises a measuring cell 7 which is fluidically connected with the sample line 4, with the liquid line 6 coming from the dilution unit 3, and with a further liquid line 8. The further liquid line 8 connects a storage container 9 with the measuring cell 7. The storage container 9 contains a reagent which is intended to be mixed with the diluted sample liquid to form a reaction mixture. The reagent undergoes a chemical reaction with the analyte, which reaction leads to the formation of a reaction product, in particular a colored reaction product, which can be detected with optical means. In one variant, the measurement unit 2 can be designed to produce the reaction mixture directly in the measuring cell 7. Alternatively, the measurement unit 2 may have a mixing device, upstream of the measuring cell 7, for producing the reaction mixture (not shown here).

[0100] In the exemplary embodiment described here, the measuring cell 7 has an optical measuring transducer 19, for example a photometer or a spectrophotometer, which serves to detect measured values representing the parameter to be determined. For example, the measuring transducer 19 may have one or more radiation sources, for example one or more LEDs, as well as one or more radiation receivers, for example one or more photodiodes, a photodiode panel or a CCD panel. The radiation source(s) and radiation receivers are arranged opposite one another in such a way that measuring radiation emitted by the radiation source(s) passes through the reaction mixture received in the measuring cell and subsequently strikes the radiation receiver(s). The radiation receiver is designed to output measurement signals which are dependent on the intensity of the received radiation and which represent an absorption or extinction of the measuring radiation in the reaction mixture.

[0101] The measuring cell 7 moreover has a liquid outlet 10 which opens into an optional collection container 11 for a waste liquid mixture. All or individual liquids conducted through the measuring cell 7 may be discharged into this collection container 11. The collection container 11 has a discharge line 12 via which the waste liquid mixture can be removed from time to time in order to supply it to a disposal. The collection container 11 is moreover connected via a fluid line 13 with a separating device 14 that is also optional.

[0102] The separating device 14 is fluidically connected with the dilution unit 3 via a further liquid line 17. The condensate collected in the condensate container of the separating device 14 may serve as dilution liquid for sample liquid taken from the sampling point and may be supplied to the dilution unit 3 via the liquid line 17. The dilution unit 3 has a storage container (not shown in more detail in FIG. 1) for the dilution liquid, into which storage container the condensate is first introduced via the liquid line 17. The dilution is carried out completely automatically by the dilution unit 3. For this purpose, it has means for metering and mixing the sample liquid and the dilution liquid, for example liquid lines and one or more pumps and valves, with which sample liquid and dilution liquid are taken from the sampling point and the storage container for dilution liquid as required and are mixed in a predetermined mixing ratio. For mixing, the dilution unit may comprise a mixing container, for example a container with a stirrer, or a liquid line with a corresponding shape or structuring, which lead to the swirling of the two liquids to be mixed. At least a portion of the diluted liquid sample thus produced may be supplied to the measurement unit 2 via the liquid line 6.

[0103] The analysis apparatus 1 may also be designed to supply the dilution liquid, optionally or at fixed time intervals, from the dilution unit 3 to the measuring cell 7 without the addition of sample liquid. This allows the implementation of zero measurements, i.e., the detection by means of the measurement unit 2 of a measured value, which represents a zero point of the analysis apparatus 1. Such a zero measurement may be used to calibrate and/or adjust the analysis apparatus 1.

[0104] The analysis apparatus has suitable controllable means, for example pumps and valves, for transporting and metering liquids. In order to fully automatically perform the dilution of the sample liquid and the detection of measured values of the measurement variable, the measurement unit in the present example moreover has a measuring and control electronics 16. The latter is connected with the measuring cell 7, in particular with the measuring transducer 19 of the measuring cell 7, in order to detect and process its measurement signals. For this purpose, the measuring and control electronics 16 has a memory with a measurement program stored therein and is designed to execute the measurement program in order to derive measured values of the parameter from the measurement signals and output them.

[0105] In addition, the measuring and control electronics 16 may be connected with the separating device 14, the dilution unit 3 and the measuring cell 7, as well as with the pumps and valves of the automatic analysis apparatus 1 which serve to transport and meter liquids. An operating program for controlling the analysis apparatus 1 is stored in the memory of such measuring and control electronics 16 and such measuring and control electronics 16 is designed to execute the operating program in order to control the pumps and valves of the analysis apparatus 1, and to meter and transport liquids according to the operating program, and to completely automatically carry out the recovery of the dilution liquid from the waste liquid mixture contained in the collection container 11, and the dilution of the sample liquid with the dilution liquid. Part of the electronics controlling the dilution of the sample liquid may be stored in the dilution unit 3 as on-site electronics.

[0106] The above-described reprocessing of the dilution liquid is to be understood merely as an optional design, which can be combined with the method according to the present disclosure.

[0107] The method according to the present disclosure can also be operated without a dilution unit, a separating device and the corresponding fluid lines. In a simplified embodiment variant, in addition to the measuring cell and the optical measuring transducer, the analysis apparatus can thus be provided merely as a storage tank for the reagent and the dilution liquid and a collection container for the liquid discharged from the measuring cell.

[0108] In enhancing DE 10 2018 131 060.9, the present disclosure in this case assumes that, in the first measurement of a sample liquid, the current value of the parameter to be measured is outside the measuring range of the optical measuring transducer used in spite of the dilution carried out or even without any dilution carried out.

[0109] If the concentration of the sample liquid is outside the measuring range of the optical measuring transducer, an accurate determination of the absorption or transmission by the optical measuring transducer is not possible and the sample liquid has to be discarded.

[0110] In order to solve this problem, a further dilution can take place according to the present disclosure within the measuring cell until the sample liquid is diluted to such an extent that the measurement is within the measuring range of the optical measuring transducer.

[0111] The measuring cell 7 can be specially designed for this purpose. Examples of embodiment variants according to the present disclosure can be found in FIGS. 2, 3 and 4.

[0112] FIG. 2 shows a first embodiment variant of a measuring cell 7a of an analysis apparatus according to the present disclosure with an enlarged capacity. The normal liquid level within the measuring cell 7a may be, for example, 50%, or even significantly less than 50%, of the capacity of the measuring cell 7a. If there is now a message that the concentration of the sample liquid is outside the measuring range of the optical measuring transducer, the liquid level FL of the reaction mixture R within the measuring cell 7a is further increased.

[0113] In the variant of FIG. 2, a compensating volume must be provided within the measuring cells 7a and is required for the additional dilution for adaptation to the measuring range. A corresponding installation space must be kept available in the analysis apparatus.

[0114] Analogously to the measuring cell 7 of FIG. 1, the measuring cell 7a has a supply line 4a, 6a and 8a for a sample, a reagent and a dilution, respectively. Of course, only one supply line may also be provided with corresponding regulation by a control valve.

[0115] A stirring element 30a of a stirring device, for example a magnetic stirrer with a stirring magnet, can be provided for the homogenization of the measuring-range-optimized dilution.

[0116] FIG. 3 shows a second embodiment variant of a measuring cell 7b of an analysis apparatus according to the present disclosure. In this variant, an open drain 3 lb for limiting the liquid level in the measuring cell 7b is provided. The feeds 4b, 6b and 8b for the sample liquid, the dilution and the reagent, in particular the feed 6b of the dilution, are shown only schematically here. In particular, the feed of dilution 6b can open into the solution near the stirring device 30.

[0117] The distance between a bottom 32b of the measuring cell 7b and the drain 3 lb in this case determines the liquid level within the measuring cell. A stirring element 30b of a stirring device 30b homogenizes the solution.

[0118] FIG. 4 shows a third embodiment variant of a measuring cell 7c.

[0119] Here, an overflow weir 33c is formed within the measuring cell 7c. A receptacle 34 for receiving diluted sample solution is located on one side of the overflow weir. A drainage shaft 35c, in which overflowing sample solution can drain, is located beyond the receptacle 34c. A stirring device 30c for homogenizing the sample solution is also provided in the variant of FIG. 4.

[0120] An example of a method for determining the parameter of the sample liquid by means of the automatic analysis apparatus 1 is described below. All steps are carried out in an automatically controlled manner by the measuring and control electronics 16.

[0121] In a first step, sample liquid is taken from the sampling point via the sample supply line 4 and is flushed into the measuring cell 7 via the liquid outlet 10 into the collection container 11. There, the sample liquid forms a waste liquid mixture with liquid already present in the collection container from earlier measurement cycles.

[0122] In a second step, the extinction or absorption of measuring radiation in the reaction mixture is detected in the measuring cell by means of the photometric or spectrometric measuring transducer, and a value of the parameter is determined on the basis of the measurement signal of the radiation detector, which measurement signal is a measure of the concentration of the reaction product in the reaction mixture.

[0123] For example, this may take place using a calibration table or calibration function stored in a memory of the measuring and control electronics 16, taking into account the dilution factor with which the sample liquid was diluted. The calibration table or calibration function associates measurement signal values with values of the measurement variable.

[0124] In a third step, the consumed reaction mixture is discharged from the measuring cell 7 into the collection container 11.

[0125] The described method may be repeated cyclically multiple times.

[0126] However, if the concentration of the sample solution is outside the measuring range of the measuring transducer, the aforementioned method has to be modified. In this case, however, the optical density of the sample solution can be determined as the second measurement variable. The current concentration of the sample solution can be estimated on the basis of the optical density, and a dilution ratio optimized for the measuring range can thereby be adjusted. For this purpose, dilution solution is passed through the supply line for dilution directly into the measuring cell. The excess volume can either be accommodated in the measuring cell (variant of FIG. 2) or, in the case of a constant liquid level, can be discharged from the measuring cell (variant of FIG. 3 or FIG. 4). By additional dilution of the sample solution within the measuring cell 7, a dilution optimized for the measuring range can take place so that the sample solution does not have to be discarded.

[0127] Alternatively to determining the second measurement variable, a defined volume of dilution solution can also be added to the reaction mixture R until the determined first measurement variable of the measuring transducer is within its measuring range.

[0128] Both variants of the method according to the present disclosure reduce the measuring outlay, the measuring time and the volume of waste solution produced

[0129] The present disclosure is not limited to the aforementioned exemplary embodiment. In principle, it is thus possible to adapt any sample solution which is located in a measuring cell and is outside the measuring range by determining a second measurement variable and sub sequent dilution.

[0130] Although the second measurement variable does not allow an exact concentration determination of the concentration of the analyte, it is sufficiently accurate for adjusting the concentration to a suitable measuring range.

[0131] Alternatively, instead of detecting a second measurement variable, iterative metering can also take place with repeated detection of the first measurement variable. In this case, a predetermined volume of dilution liquid is fed into the sample solution of the measuring cell until the detection of the first measurement variable reveals that the detected measurement variable is within the measuring range of the optical measuring transducer.

[0132] Preferably, and not shown in FIGS. 2-4, the feed of dilution solution or the drain from the measuring cell 7a-7c comprises a measuring device for determining the volume supplied. This can be, for example, a magnetically inductive flowmeter, an impeller counter or the like. It is also possible to select a uniform metered volume, for example by means of an upstream metering container.

[0133] The dilution of the sample liquid after the detection of the first measurement variable within the measuring cell, preferably the measuring cuvette, results in a time saving and a reduced consumption of dilution liquid.

[0134] A multitude of further variants and exemplary embodiments of the present disclosure are conceivable.

[0135] The advantages of the method according to the present disclosure and of the analysis apparatus according to the present disclosure are that, on the one hand, the measuring range end can be increased, without simultaneously increasing the measuring range beginning, and consequently the measurement ratio.

[0136] Furthermore, the concentration in the method according to the present disclosure and when using the analysis apparatus according to the present disclosure need not be approximately known in order to determine the specific dilution ratio. This knowledge of the approximate concentration range can advantageously be omitted by determining the second measurement variable or by iterative approximation to the measuring range.

[0137] In addition, the consumption of dilution liquid is minimized in this type of application.

[0138] Since the dilution takes place in the measuring cell or in a measuring cuvette, no additional vessels and apparatuses are necessary for the dilution. It is thus also possible for the dilution unit 3 of FIG. 1 to advantageously be omitted, which represents an apparatus simplification of the analysis apparatus.