Analytical device

Abstract

To measure the optical characteristics of a solute included in a solution by allowing the solution containing as a solvent a liquid mixture of multiple kinds of liquid to flow to a flow cell of a detector.SOLUTION: An analyzer comprises: a solution supply unit for supplying a solution containing as a solvent a liquid mixture of multiple kinds of liquid; a detector provided with a flow cell to which the solution supplied by the solution supply unit flows, for measuring the optical characteristics of the solution flowing in the flow cell; a characteristic holding unit for holding characteristic information regarding the optical characteristics of each of the multiple kinds of liquid; and an arithmetic processing unit configured to deduce a mixture ratio of the multiple kinds of liquid constituting the solvent in the solution whose optical characteristics have been measured from a preliminary set analysis condition, calculate the optical characteristics of the solvent in the solution, as background, whose optical characteristics have been measured, using the deduced mixture ratio and the characteristic information held in the characteristic holding unit, and deduct the background from the optical characteristics of the solution to calculate the optical characteristics of a solute in the solution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an analytical device using a detector whose measured values ​​are affected by the composition of the solvent in the solution flowing through a flow cell. [Background technology]

[0002] Some detectors used in analytical devices use the optical properties of substances to detect the presence or absence and type of substances. Known detection methods include Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, which use vibrational spectroscopy (see Patent Document 1). These detection methods do not restrict the state of the sample used for measurement, and can measure samples in various states, including solids, liquids, and gases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-117022 Summary of the Invention [Problem to be solved by the invention]

[0004] When a sample solution is applied to a detector such as the one described above, the detection data obtained by the detector includes not only signals attributable to the sample in the sample solution but also signals attributable to the solvent. For example, if an attempt is made to obtain the Raman spectrum, which is an optical characteristic, by applying a caffeine solution to a Raman spectroscopic detector, the obtained Raman spectrum will include the Raman spectrum of caffeine and the Raman spectrum of the solvent, water. In many cases, the proportion of the sample in the sample solution is small compared to the solvent, making the Raman spectrum of the sample obscured by the Raman spectrum of the solvent, making it difficult to accurately measure the Raman spectrum of the sample. In such cases, since the Raman spectrum of water is known, it is possible to obtain the Raman spectrum of caffeine by subtracting the background Raman spectrum of water from the Raman spectrum of the caffeine solution. In this way, when measuring a solution containing only one target component, the Raman spectrum of the target component can be obtained by simply subtracting the Raman spectrum of the solvent from the Raman spectrum measured for the solution.

[0005] On the other hand, for sample solutions containing a mixture of target components, such as a methanol solution containing methylparaben and ethylparaben, it is possible to separate the components in the sample solution by liquid chromatography before feeding them to a Raman spectrometer. In this case, it is efficient to directly introduce the eluate from the liquid chromatography separation column into the flow cell of the Raman spectrometer and acquire the Raman spectrum of the target component in real time. However, the mobile phase in liquid chromatography is often a mixture of multiple liquids (e.g., water and organic solvents), and the background Raman spectrum of the mobile phase is unknown. Furthermore, liquid chromatography sometimes involves gradient analysis, in which the mixture ratio of multiple liquids constituting the mobile phase is changed over time. In such cases, the Raman spectrum of the mobile phase flowing through the flow cell of the Raman spectrometer changes over time, making it difficult to acquire the Raman spectrum of the target component in real time while the liquid chromatography is running.

[0006] The present invention has been made in consideration of the above problems, and aims to make it possible to measure the optical properties of solutes contained in a solution containing a mixture of multiple types of liquids as a solvent by flowing the solution through a flow cell of a detector. [Means for solving the problem]

[0007] The analytical apparatus of the present invention includes a solution supply unit that supplies a solution having a mixture of multiple types of liquids as a solvent, a flow cell through which the solution supplied by the solution supply unit flows and a detector that measures the optical properties of the solution flowing through the flow cell, a property storage unit that stores property information regarding the optical properties of each of the multiple types of liquid, and an arithmetic processing unit that is configured to: determine a mixing ratio of the multiple types of liquids that constitute the solvent of the solution flowing through the flow cell from predetermined analysis conditions; use the determined mixing ratio and the property information stored in the property storage unit to calculate the optical properties of the solvent in the solution whose optical properties have been measured as a background; and calculate the optical properties of the solute in the solution by subtracting the background from the optical properties of the solution. [Effects of the Invention]

[0008] According to the analytical device of the present invention, the optical properties of the solvent flowing through the flow cell at the time the detector measures the optical properties of the solution are calculated using the optical properties prepared in advance for each of the multiple types of liquid that make up the solvent, and this is used as a background.The optical properties of the solute are then calculated by subtracting the background from the optical properties of the solution measured by the detector.Therefore, by flowing a solution containing a mixture of multiple types of liquids as a solvent through the flow cell of the detector, the optical properties of the solute contained in that solution can be measured. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram showing an example of an analysis device. [Figure 2] 10 is a flowchart showing an example of an analysis operation in the embodiment. [Figure 3] 10 is an example of optical characteristics stored in a characteristic storage unit. [Figure 4] 10 is an example of a background calculated using the optical properties of each liquid stored in the property storage unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of an analytical device according to the present invention will be described below with reference to the drawings.

[0011] FIG. 1 shows a schematic configuration of this embodiment.

[0012] The analytical device 1 in this embodiment is a liquid chromatograph. The analytical device 1 includes a liquid delivery device 4, an injector 6, a separation column 8, an oven 9, a detector 10, a control unit 12, a management device 14, and a display 30.

[0013] The liquid delivery device 4 delivers the mobile phase to the analysis flow path 2. In this embodiment, the liquid delivery device 4 delivers two types of liquids A and B using two pumps, mixes them in a mixer, and delivers the mixture of liquids A and B to the analysis flow path 2 as the mobile phase.

[0014] The injector 6 injects a sample into the mobile phase flowing through the analysis flow path 2. The separation column 8 is housed in an oven 9 and controlled to a set temperature. The separation column 8 is provided downstream of the injector 6 on the analysis flow path 2. The multiple components in the sample injected into the mobile phase by the injector 6 are separated in time from one another and sequentially elute from the separation column 8 together with the mobile phase solvent delivered from the solution delivery device 4. The components eluted from the separation column 8 are introduced into a flow cell 16 of a detector 10, which will be described later. In other words, the solution delivery device 4, the injector 6, and the separation column 8 constitute a solution supply unit that supplies a solution containing the mobile phase delivered by the solution delivery device 4 as a solvent and the target component separated from other components in the separation column 8 as a solute to the flow cell 16 of the detector 10.

[0015] Detector 10 is provided downstream of separation column 8 on analysis flow path 2. Detector 10 can be a Raman spectroscopic detector, FTIR, or other detector that measures the optical properties of the eluate from separation column 8. In this embodiment, detector 10 is described as a Raman spectroscopic detector. Detector 10 includes a flow cell 16 through which the eluate from separation column 8 flows, a light source 18 that irradiates flow cell 16 with excitation light, and a sensor 20 that detects Raman scattered light from the eluate flowing through flow cell 18. Each component separated from the others in separation column 8 is eluted by a solvent delivered from solution delivery device 4. Detector 10 measures the Raman spectrum, which is the optical property of the solution flowing through flow cell 16, and outputs a signal (Raman spectrum signal) corresponding to the measured Raman spectrum to management device 14.

[0016] The control unit 12 controls the operations of the liquid delivery device 4, the injector 6, and the oven 9. The control unit 12 is realized by an electronic circuit including a processor. The control unit 12 is, for example, a dedicated system controller.

[0017] The management device 14 manages the operation of the analysis device 1 through the control unit 12 and is realized, for example, by a general-purpose personal computer. The management device 14 includes an arithmetic processing unit 22, a characteristic storage unit 24, a correction data storage unit 26, and an analysis condition storage unit 28. The arithmetic processing unit 22 is a function realized by the processor of the management device 14 executing a predetermined program. The characteristic storage unit 24, the correction data storage unit 26, and the analysis condition storage unit 28 are each functions realized by a partial storage area of ​​an information storage device of the management device 14. The display 30 is connected to the management device 14.

[0018] In this embodiment, the management device 14 is provided with the characteristic storage unit 24 and the correction data storage unit 26, but the present invention is not limited to this, and at least one of the characteristic storage unit 24 and the correction data storage unit 26 may be provided in the control unit 12, or may be provided in a database on the network to which the management device 14 is connected.

[0019] Before performing an analysis, the user inputs analysis conditions into the management device 14. The analysis conditions input by the user into the management device 14 are stored in the analysis condition storage unit 28. The analysis conditions stored in the analysis condition storage unit 28 include the type, pH, liquid delivery rate, and liquid delivery pressure of each of the liquids A and B delivered by the liquid delivery device 4, and particularly, when gradient analysis is performed, a gradient program related to the liquid delivery rate (mixing ratio of liquids A and B) of each of the liquids A and B for each elapsed time after the start of the analysis, the amount of sample injected by the injector 6, and the set temperature of the oven 9. The management device 14 provides instructions based on the analysis conditions stored in the analysis condition storage unit 28 to the control unit 12, and the control unit 12 controls the operations of the liquid delivery device 4, the injector 6, and the oven 9 based on the instructions provided by the management device 14.

[0020] The calculation processing unit 22 is configured to read the Raman spectrum signal output from the detector 10 and calculate the Raman spectrum of the target component (solute) in the eluate from the separation column 8. The Raman spectrum of the target component in the eluate from the separation column 8 is obtained by subtracting the background Raman spectrum signal of the mobile phase (solvent) from the Raman spectrum of the eluate (solution) from the separation column 8 measured by the detector 10.

[0021] The Raman spectrum of the mobile phase in the eluent can be calculated using the Raman spectra of each of the liquids A and B that make up the mobile phase. The Raman spectra of the liquids A and B that make up the solvent are known or have been obtained by prior measurement and are stored in the property storage unit 24. The Raman spectrum data of each of the liquids A and B stored in the property storage unit 24 is the digitized data shown in FIG. 3. FIG. 3 shows the Raman spectrum data of water and methanol used as the liquids A and B, respectively. In this data, the horizontal axis represents the Raman shift (the amount of shift in the wavelength of the detected light from the wavelength of the excitation light) and the vertical axis represents the signal intensity.

[0022] It is known that the intensity of Raman scattered light is proportional to the concentration of a substance in a solution. Therefore, when the mixture ratio of liquid A and liquid B is X:Y, the Raman spectrum Ra of the mobile phase is the Raman spectrum Ra of liquid A. A and Raman spectra of liquid B, Ra B Using this, it can be calculated using the following equation (1). Ra=Ra A ×X / (X+Y)+Ra B ×Y / (X+Y) (1) By using the above formula (1), it is possible to obtain Raman spectrum data for a mobile phase with a desired composition, as shown in Figure 4. The examples in Figure 4 show Raman spectrum data for mixtures of methanol and water with a mixing ratio of 2:8, 4:6, 6:4, and 8:2.

[0023] As described above, the background Raman spectrum derived from the solvent can be calculated using the Raman spectral data of liquids A and B prepared in advance. This is particularly effective in gradient analysis, in which the composition of the mobile phase changes over time. That is, the mixture ratio of liquids A and B constituting the mobile phase flowing through the flow cell 16 at a given time can be calculated from a gradient program set in advance as an analysis condition. Therefore, after the gradient program is set and before the analysis begins, the composition of the mobile phase for each time period can be calculated, and the Raman spectral data derived from the mobile phase for each time period can be calculated as the background. The composition of the mobile phase when the target component separated in the separation column 8 flows through the flow cell 16 can be accurately calculated by considering the gradient program as well as the system capacity between the solution delivery device 4 and the flow cell 16. The system capacity can be stored in the management device 14. By subtracting the background calculated in this way from the Raman spectrum of the eluate acquired by the detector 10 during the analysis, the Raman spectral data of the target component separated in the separation column 8 can be obtained.

[0024] It is also known that the position of a peak in a Raman spectrum shifts depending on the temperature, pH, type of solvent, and excitation wavelength of the solution flowing through the flow cell 16. Therefore, the position of the background peak calculated as described above can be corrected based on analytical conditions such as the set temperature of the oven 9, the pH of the mobile phase, type of solvent, and excitation wavelength. The correction data storage unit 26 stores correction data that indicates the correlation between analytical conditions that affect the position of the peak in the Raman spectrum, such as temperature, pH, type of solvent, and excitation wavelength, and the amount of shift of a specific peak in the Raman spectrum. The calculation processing unit 22 uses the correction data stored in the correction data storage unit 26 to correct the position of a specific peak in the calculated background according to analytical conditions such as temperature, pH, type of solvent, and excitation wavelength. This allows for more accurate background data to be obtained that matches the analytical conditions.

[0025] Furthermore, the intensity of the Raman scattered light detected by the detector 10 varies depending on the intensity of the excitation light from the light source 18, the amount of sample injected into the mobile phase, temperature, and the like. Therefore, simply subtracting the background calculated using the Raman spectral data of each liquid A and B prepared in advance from the measured Raman spectral data may result in excessive background removal. To avoid this situation, it is effective to normalize the calculated background intensity using the intensity of the Raman spectrum (e.g., the height of a specific peak) measured after the analysis has actually begun. For example, the calculation and control unit 22 can be configured to acquire from the detector 10 Raman spectral data measured when only the mobile phase is flowing through the flow cell 16 immediately after the analysis has begun, and then correct the calculated background intensity based on the intensity of the acquired Raman spectral data.

[0026] An example of the analytical operation of this embodiment will be described with reference to the flowchart of Fig. 2 together with Fig. 1. The following describes the case of gradient analysis in which the composition of the mobile phase is changed over time.

[0027] Assume that the analysis conditions are set in advance by the user in the management device 14. The calculation processing unit 22 refers to the analysis conditions stored in the analysis condition storage unit 28, and based on the gradient program, identifies the composition of the mobile phase flowing through the flow cell 16 (mixing ratio of liquids A and B) in each time period after the start of the analysis, and calculates the Raman spectrum (background) derived from the mobile phase in each time period (steps 101 and 102).

[0028] While the initial mobile phase is being delivered to the analysis flow path 2 by the liquid delivery device 4, the detector 10 measures the Raman spectrum of the mobile phase flowing through the flow cell 16 (step 103). The measured Raman spectrum intensity is then used to correct and normalize the calculated background intensity for each time period (step 104). Furthermore, the position of a specific peak in the background is corrected, if necessary, based on the temperature of the mobile phase (the set temperature of the oven 9), the pH of the mobile phase, the type of solvent constituting the mobile phase, the wavelength of the excitation light, etc.

[0029] During the analysis, detector 10 measures the Raman spectrum at regular intervals (step 105). At the measurement time, detector 10 measures the Raman spectrum of the eluate from separation column 8 (step 106). Processing unit 22 subtracts the background at the measurement time, which was calculated in advance, from the Raman spectrum measured by detector 10, to calculate the Raman spectrum derived from the target component contained in the eluate (step 107). The calculated Raman spectrum data of the target component can be displayed in real time on display 30 (step 108). The operations of steps 105 to 109 are repeatedly executed at each measurement time that arrives at regular intervals until the analysis is completed.

[0030] In the above description, the background for each time period is determined before the analysis begins, but the present invention is not limited to this. The background may be calculated during or after the analysis and subtracted from the measured Raman spectrum. For example, immediately after the analysis begins and the Raman spectrum of the eluate from the separation column 8 is measured, the composition of the mobile phase at that time may be determined to calculate the background, and the background may be corrected based on the analysis conditions, etc., and then subtracted from the measured Raman spectrum of the eluate. Alternatively, the background for each time period during the analysis may be calculated after the analysis is completed, and the background for the corresponding time period may be subtracted from the Raman spectrum of the eluate obtained in the analysis.

[0031] The above explanation is based on the premise of gradient analysis, but the mixing ratio of the multiple liquids that make up the mobile phase may be constant over time. In that case, the only thing that will be constant from the start to the end of the analysis is the background, which is still calculated.

[0032] That is, embodiments of the analyzer according to the present invention are as follows.

[0033] In one embodiment of the analytical device according to the present invention, the device includes: a solution supply unit that supplies a solution containing a mixture of multiple types of liquids as a solvent; a flow cell through which the solution supplied by the solution supply unit flows, the detector measuring the optical properties of the solution flowing through the flow cell; a property storage unit that stores property information regarding the optical properties of each of the multiple types of liquid; and an arithmetic processing unit configured to: determine a mixing ratio of the multiple types of liquids that constitute the solvent in the solution whose optical properties have been measured from predetermined analysis conditions; use the determined mixing ratio and the property information stored in the property storage unit to calculate the optical properties of the solvent in the solution whose optical properties have been measured as a background; and calculate the optical properties of the solute in the solution by subtracting the background from the optical properties of the solution.

[0034] In a first aspect of the above embodiment of the analytical device according to the present invention, the solution supply unit includes a liquid delivery device that delivers the solvent, an injector that injects a sample into the solvent delivered by the liquid delivery device, and a separation column that separates multiple components contained in the sample injected into the solvent by the injector, and supplies a solution containing the individual components separated by the separation column as solutes to the flow cell of the detector. In this aspect, it is possible to measure the optical properties of the target component while flowing a solution containing the target component as solute, which has been separated from other components by liquid chromatography, through the flow cell.

[0035] In the first aspect, the analysis conditions may include a gradient program for changing over time the mixing ratio of the plurality of liquids constituting the solvent delivered by the liquid delivery device, thereby enabling the background to be changed over time in accordance with the change over time in the composition of the solvent even when gradient analysis is performed in liquid chromatography, thereby enabling accurate measurement of the optical properties of the target component.

[0036] In the above case, the analysis conditions include a liquid delivery flow rate by the liquid delivery device and a system capacity, which is the capacity of a distribution path for the solution from the liquid delivery device to the flow cell, and the arithmetic processing unit can be configured to calculate a mixing ratio of the plurality of types of liquids that constitute the solvent in the solution whose optical properties have been measured, based on the liquid delivery flow rate and the system capacity, thereby improving the accuracy of the background.

[0037] In a second aspect of the above embodiment of the analytical device according to the present invention, the arithmetic processing unit is configured to normalize the background obtained by the calculation using the intensity of the optical property of the solvent measured by the detector at a predetermined timing when only the solvent flows through the flow cell before the start of the analysis. This aspect allows a more accurate background to be obtained, improving the measurement accuracy of the optical property of the target component.

[0038] In a third aspect of the above embodiment of the analytical device according to the present invention, the detector is a Raman spectrophotometer that measures a Raman spectrum as the optical property, and the property storage unit stores the Raman spectrum of each of the plurality of types of liquid.

[0039] In the third aspect, the apparatus may further include a correction data storage unit that stores correction data indicating a correlation between specific analytical conditions that affect the Raman spectrum and the magnitude of the effect of the specific analytical conditions on the Raman spectrum, and the arithmetic processing unit may be configured to correct the background based on the correction data and calculate the optical properties of the solute in the solution by subtracting the corrected background from the optical properties of the solution. This allows a background that takes into account the specific analytical conditions that cause fluctuations in the Raman spectrum to be used in the measurement, thereby improving the measurement accuracy of the optical properties of the target component.

[0040] In the above case, the specific analysis condition can be the temperature and / or pH of the solution flowing through the flow cell, and the correction data storage unit can store, as the correction data, a correlation between the temperature of the solution, the type of solvent, the wavelength of excitation light, and / or the pH value and the amount of shift of the peak position in the Raman spectrum. [Explanation of symbols]

[0041] 1. Liquid chromatograph (analytical equipment) 2. Analysis channel 4. Liquid delivery device 6 injectors 8 Separation column 9. Oven 10 Detector 12 Control Unit 14 Management device 16 flow cells 18 light source 20 sensors 22 Processing unit 24 Characteristic retention part 26 Correction data storage unit 28 Analysis condition holding section 30 Display

Claims

1. A solution supply unit that supplies a solution containing a solute and a solvent, the solvent being a mixture of multiple types of liquids; a detector including a flow cell through which the solution supplied by the solution supply unit flows, the detector measuring optical characteristics of the solution flowing through the flow cell; a characteristic storage unit that stores characteristic information regarding the optical characteristics of each of the plurality of types of liquid; an arithmetic processing unit configured to: determine a mixing ratio of the multiple types of liquids constituting the solvent in the solution whose optical properties have been measured from predetermined analysis conditions; calculate the optical properties of the solvent in the solution whose optical properties have been measured as a background using the determined mixing ratio and the property information stored in the property storage unit; and calculate the optical properties of the solute in the solution by subtracting the background from the optical properties of the solution.

2. 2. The analytical apparatus according to claim 1, wherein the solution supply unit includes a liquid delivery device that delivers the solvent, an injector that injects a sample into the solvent delivered by the liquid delivery device, and a separation column that separates multiple components contained in the sample injected into the solvent by the injector, and supplies the solution containing the individual components separated by the separation column as the solute to the flow cell of the detector.

3. The analytical device according to claim 2 , wherein the analysis conditions include a gradient program for changing over time a mixing ratio of the plurality of types of liquids that constitute the solvent delivered by the liquid delivery device.

4. the analysis conditions include a liquid delivery flow rate by the liquid delivery device and a system capacity which is a capacity in a distribution path of the solution from the liquid delivery device to the flow cell; 4. The analytical device according to claim 3, wherein the calculation processing unit is configured to calculate a mixing ratio of the plurality of types of liquids constituting the solvent in the solution whose optical characteristics have been measured, based on the liquid delivery flow rate and the system capacity.

5. 5. The analytical device according to claim 1, wherein the arithmetic processing unit is configured to normalize the background obtained by the calculation using an intensity of the optical property of the solvent measured by the detector at a predetermined timing when only the solvent flows through the flow cell from before the start of analysis.

6. the detector is a Raman spectrophotometer that measures a Raman spectrum as the optical property; The analytical device according to claim 1 , wherein the characteristic storage unit stores Raman spectra of the plurality of types of liquids.

7. a correction data storage unit that stores correction data indicating a correlation between specific analytical conditions that affect the Raman spectrum and the magnitude of the effect of the specific analytical conditions on the Raman spectrum, 7. The analytical device according to claim 6, wherein the calculation processing unit is configured to correct the background based on the correction data, and to obtain the optical properties of the solute in the solution by subtracting the corrected background from the optical properties of the solution.

8. the specific analysis conditions are a temperature, a type of solvent, an excitation light wavelength, and / or a pH of the solution flowing through the flow cell; 8. The analytical instrument according to claim 7, wherein the correction data storage unit stores, as the correction data, a correlation between a temperature, a type of solvent, an excitation light wavelength, and / or a pH value of the solution and a shift amount of a peak position in the Raman spectrum.

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