Analysis method using a spectrometer

Abstract

To acquire spectral data of a component to be analyzed in a solution flowing through a flow cell with high signal intensity.SOLUTION: An analysis method for obtaining spectrum data of a component to be analyzed includes: a step of determining a target wavelength range to be acquired based on the difference in signal intensity between spectrum data of a sample solution acquired by a spectrum measurement device 10 and spectrum data of a solvent acquired in advance; a step of using the spectrum data of the sample solution and the spectrum data of the solvent acquired in a spectrum acquisition step as condition-compatible spectrum data of the sample solution and the solvent, respectively, if the signal intensity level of the spectrum data in the target wavelength range is within a predetermined reference range; and a calculation step of obtaining the spectrum data of the component to be analyzed in the target wavelength range by subtracting the condition-compatible spectrum data of the solvent from the condition-compatible spectrum data of the sample solution in the target wavelength range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an analytical method using a spectrum measuring device. [Background technology]

[0002] Liquid chromatography (LC) is often used to identify the substance of each of a mixture of multiple components. In liquid chromatography, multiple components are separated from each other using a separation column, and each component eluted from the separation column is generally detected by measuring changes in the optical properties of the eluate using a UV detector, PDA detector, RID detector, etc.

[0003] On the other hand, there are substances for which accurate identification results cannot be obtained using the above-mentioned general LC detectors due to problems with chemical properties and sensitivity. In such cases, a device such as a Raman spectrometer (see Patent Document 1) is used to measure the optical properties, such as the Raman spectrum, of the components to be analyzed, and the substance of each component is identified from the measured optical properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-117022 Summary of the Invention [Problem to be solved by the invention]

[0005] When identifying components separated in an LC separation column using a spectrometer such as a Raman spectrometer, it is common to first dry the eluate droplets to evaporate the solvent and then measure the spectra of the target components using the spectrometer. However, this method does not allow for online analysis from component separation to identification, and it also requires a long analysis time. Therefore, it is desirable to directly introduce the eluate from the separation column into the spectrometer and obtain spectral data of the target components.

[0006] To obtain spectral data of the analyte components in real time, the eluate from the separation column must be introduced into a flow cell and the spectrum of the eluate flowing through the flow cell must be measured. However, because the eluate flowing through the flow cell contains the solvent in addition to the analyte components, the spectra of the analyte and the solvent overlap when measured. Therefore, to obtain spectral data derived from the analyte components, a calculation process is required to subtract the spectral data of the solvent from the spectral data of the eluate.

[0007] However, because the amount of analyte in the eluate from the separation column is overwhelmingly small compared to the amount of solvent, the signal intensity of the analyte-derived spectral data obtained by subtracting the solvent-derived spectral data from the eluate-derived spectral data is extremely low. The signal intensity of the spectral data can be increased by increasing the excitation light intensity or lengthening the spectral measurement time. However, excessively high excitation light intensity can lead to denaturation of the analyte in the flow cell. Furthermore, extending the spectral measurement time can lead to spectral measurement continuing after the analyte has passed the flow cell, potentially reducing the accuracy of the spectral data. To avoid these problems, one could consider reducing the LC mobile phase flow rate to extend the time the analyte flows through the flow cell. However, changing the mobile phase flow rate could result in improper component separation in the separation column. Simply increasing the signal intensity of the sample solution's spectral data could lead to saturation somewhere in the measurement wavelength range due to the increased signal intensity of the solvent-derived spectral data.

[0008] The present invention has been made in view of the above problems, and has as its object to make it possible to acquire spectral data of an analyte component in a solution flowing through a flow cell with high signal intensity. [Means for solving the problem]

[0009] The analytical method according to the present invention is an analytical method for acquiring spectral data of a target component by using a spectroscopic measurement device that is configured to perform spectral measurement of the liquid flowing through the flow cell, the spectroscopic measurement device including a flow cell through which a liquid flows and a light detection unit for detecting the amount of light emitted from the flow cell for each wavelength band, and the method comprising: a spectrum acquisition step of provisionally setting condition parameters for the spectrum measurement of the spectrum measurement device, performing the spectrum measurement on a sample solution containing an analyte component, and acquiring spectral data of the sample solution; a target wavelength range determination step of determining a target wavelength range in which the spectral data of the analyte component should be acquired based on a difference in signal intensity between the spectral data of the sample solution and the spectral data of the solvent previously acquired after the spectrum acquisition step; a condition-matched spectrum acquisition step of: when the signal intensity level of the spectral data in the target wavelength range is within a predetermined reference range, setting the spectral data of the sample solution and the spectral data of the solvent acquired in the spectrum acquisition step as condition-matched spectral data of the sample solution and the solvent, respectively; when the signal intensity level of the spectral data in the target wavelength range is outside the predetermined reference range, changing the condition parameters so that the signal intensity level of the spectral data in the target wavelength range is within the reference range, and performing the spectrum measurement on the sample solution again to acquire condition-matched spectral data for the target wavelength range of the sample solution that falls within the reference range, and acquiring condition-matched spectral data for the solvent; and a calculation step of subtracting the condition-matched spectral data of the solvent from the condition-matched spectral data of the sample solution in the target wavelength range to obtain spectral data of the analyte component in the target wavelength range.

[0010] Here, determining the target wavelength range based on the difference in signal intensity between the spectral data of the sample solution and the solvent means determining the wavelength range in which the difference in signal intensity between the spectral data of the sample solution and the solvent is larger than other wavelength ranges, i.e., the wavelength range in which the spectral characteristics of the analyte component are relatively well represented as the target wavelength range. That is, in the analytical method of the present invention, the spectral measurement condition parameters are first provisionally set, and the spectral measurement of the sample solution is performed. The spectral data of the sample solution obtained in the spectral measurement is compared with the spectral data of the solvent previously acquired, and the wavelength range in which the spectral characteristics of the analyte component are relatively well represented is determined as the target wavelength range for acquiring the spectral data of the analyte component. Here, if the signal intensity of the spectral data of the solvent within the target wavelength range is already within a predetermined reference range, the already acquired spectral data is treated as "condition-compliant spectral data." On the other hand, if the signal intensity of the spectral data of the solvent within the target wavelength range is outside the reference range, the condition parameters are changed so that the signal intensity level of the spectral data of the sample solution within the target wavelength range falls within the reference range, and the spectral measurement of the sample solution is performed again, ultimately obtaining "condition-compliant spectral data" for the sample solution and the solvent. Then, the "condition-matching spectral data" of the solvent is subtracted from the "condition-matching spectral data" of the sample solution within the target wavelength range, thereby obtaining spectral data of the analyte component within the target wavelength range. [Effects of the Invention]

[0011] As described above, the analytical method of the present invention focuses only on the target wavelength range in which the spectral characteristics of the component to be analyzed appear, and if the signal intensity of the spectral data in that target wavelength range is outside a predetermined reference range, the condition parameters of the spectrometer are changed so that the signal intensity level of the spectral data of the sample solution in that target wavelength range falls within the reference range, and the spectral measurement is performed again.Finally, spectral data for the component to be analyzed is obtained within a limited wavelength range, so that spectral data with high signal intensity can be obtained for the target wavelength range in which the spectral characteristics of the component to be analyzed appear. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of an analysis device including a spectrum measurement device. [Figure 2] 1 is a flowchart illustrating an example of an analysis method. [Figure 3] 1 is an example of superimposed spectral data of a sample solution and spectral data of a solvent. [Figure 4] FIG. 10 is a conceptual diagram for explaining the calculation process of subtracting the spectral data of a solvent from the spectral data of a sample solution in a target wavelength range. [Figure 5] FIG. 10 is a conceptual diagram for explaining a synthesis process for joining together spectral data of a component to be analyzed in a plurality of target wavelength ranges. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the analysis method according to the present invention will be described below with reference to the drawings.

[0014] An example of an analytical system used to carry out the analytical method of the present invention is shown in FIG.

[0015] The analytical system in FIG. 1 is an LC system, and includes an analytical flow path 2, a liquid delivery pump 4, an injector 6, a separation column 8, a spectrometer 10, a processor 12, a display 14, and an input device 16.

[0016] The liquid delivery pump 4 delivers the mobile phase through the analysis flow path 2. The injector 6 injects the sample into the mobile phase flowing through the analysis flow path 2. The separation column 8 separates the components contained in the sample injected into the mobile phase by the injector 6. The spectrum measurement device 10 is a Raman spectrometer equipped with a flow cell 18 through which the eluate from the separation column 8 flows, an excitation light source 20 that irradiates the eluate flowing through the flow cell 18 with excitation light, and a photodetector 22 that detects Raman scattered light from the eluate excited by the excitation light in each wavelength band to measure the Raman spectrum of the eluate. The arithmetic processing device 12 is a computer configured to perform arithmetic processing using the Raman spectrum data output from the photodetector 22 of the spectrum measurement device 10. The display 14 displays various information output from the arithmetic processing device 12. The input device 16 is a keyboard or the like that allows a user to input information to the arithmetic processing device 12.

[0017] Next, an example of an analysis method using the above-described analysis system will be described with reference to the flowchart of FIG. 2 together with FIG.

[0018] [Step 101: Spectral Measurement] LC analysis is performed under conditions (mobile phase flow rate, column temperature, etc.) that allow the target component to be well separated from other components. The condition parameters (excitation light intensity, exposure time, number of integrations, slit width, etc.) of the spectrometer 10 are provisionally set, and Raman spectra are measured for a portion of the eluate from the separation column 8 that contains the target component (sample solution) and a portion that does not contain the target component (solvent). The spectral data of the sample solution and the solvent obtained by the spectrometer 10 are loaded into the arithmetic processing device 12 and displayed on the display 14. To facilitate comparison of the spectral data of the sample solution and the solvent, the data are preferably displayed superimposed on the display 14.

[0019] [Step 102: Determine the target wavelength range] The spectral data of the sample solution and the solvent displayed on the display 14 are compared, and one or more wavelength ranges (wavenumber ranges) in which the difference in signal intensity between the two is larger than other wavelength ranges (wavenumber ranges) are determined as the target wavelength range. Alternatively, a wavelength range in which no peak exists in the spectral data of the solvent but a peak exists in the spectral data of the sample solution may be determined as the target wavelength range. Since the target wavelength range determined here is considered to be a characteristic portion of the Raman spectrum of the component to be analyzed within the entire measurement wavelength range, subsequent steps are performed focusing only on the target wavelength range.

[0020] [Step 103: Evaluate Signal Strength] For each of the one or more target wavelength ranges determined in step 102, the signal intensity level of the spectral data within each target wavelength range is evaluated to determine whether it falls within a predetermined reference range. The predetermined reference range is a reference range that determines whether there is room for improving the signal intensity of the spectral data of the sample solution within each target wavelength range without saturating it, or whether it is desirable to improve it. This range can be set based on the detection limit intensity of the spectrum measurement device 10. For example, the reference range can be set so that the upper limit is 100% of the detection limit intensity and the lower limit is 80% of the detection limit intensity. Whether the signal intensity level falls within the reference range can be determined, for example, by determining whether the maximum value of the signal intensity of the spectral data of the sample solution within the target wavelength range reaches the upper limit of the reference range or whether the minimum value of the signal intensity of the spectral data of the sample solution within the target wavelength range is equal to or greater than the lower limit of the reference range.

[0021] [Step 104: Acquiring Optimized Spectral Data] For a target wavelength range in which the signal intensity level of the spectral data within that target wavelength range is evaluated in step 103 as being within a predetermined reference range, the spectral data of the sample solution and the spectral data of the solvent acquired in step 101 can be used as the "condition-compliant spectral data" of the sample solution and the solvent for that target wavelength range, respectively.

[0022] On the other hand, for target wavelength ranges for which the signal intensity level of the spectral data within the target wavelength range is evaluated in step 103 as being outside the predetermined reference range, condition parameters are set in the spectrometer 10 so that the signal intensity of the spectral data within that target wavelength range falls within the reference range, and spectral measurements are re-performed for each of the sample solution and the solvent without changing the LC analysis conditions. If there are multiple target wavelength ranges for which the signal intensity level of the spectral data falls outside the predetermined reference range, condition parameters for the spectrometer 10 are determined for each target wavelength range so that the signal intensity of the spectral data falls within the reference range, and spectral measurements are performed for the sample solution and the solvent using each condition parameter. The spectral data of the sample solution and the spectral data of the solvent obtained in the re-performed spectral measurements are designated as the "condition-compliant spectral data" of the sample solution and the solvent for that target wavelength range, respectively.

[0023] [Step 105: Calculation Processing] The "condition-matching spectral data" of the solvent is subtracted from the "condition-matching spectral data" of the sample solution obtained in step 104 for each target wavelength range, thereby obtaining spectral data of the analyte component in each target wavelength range. Note that in the description up to this point, spectral measurements are performed for each of the sample solution and the solvent, and condition-matching spectra are obtained for each of the sample solution and the solvent. However, the present invention is not limited to this. The spectral data of the solvent may be prepared in advance. In this case, the prepared spectral data can be corrected before analysis, taking into account the condition parameters changed to obtain the condition-matching spectrum of the sample solution, to obtain the condition-matching spectral data of the solvent.

[0024] [Step 106: Composition Processing] The spectral data of the analyte component in each target wavelength range acquired in step 105 above is combined to generate virtual spectral data for the analyte component. The spectral data combined in this combination process may not be based on data acquired under the same measurement conditions (condition parameters), but this does not pose a problem as data for identifying the substance of the analyte component. Note that if there is only one target wavelength range, this combination process may result in spectral data in which the signal intensity outside the target wavelength range is set to a reference intensity (e.g., zero).

[0025] [Step 107: Identification of Analyte] The hypothetical spectral data for the target component of analysis created in step 106 is referenced to a database within the arithmetic processing device 12 or a database storing spectral information for substances on the network to which the arithmetic processing device 12 is connected, thereby identifying the type of substance that is the target component of analysis.

[0026] A specific example of the above analysis method will be explained using the data in FIGS. 3 to 5 together with FIG.

[0027] Assume that the spectral data shown in Figure 3 is obtained for the sample solution and the solvent by the spectral measurement in step 101. The horizontal axis of Figure 3 is the Raman shift [cm], which indicates the amount of shift in the wavelength of the Raman scattered light relative to the wavelength of the excitation light. -1 ], where the waveform drawn with a thick line is the spectral data of the sample solution (the eluate containing the analyte), and the waveform drawn with a thin line is the spectral data of the solvent (the eluate not containing the analyte). -1 ~1600cm -1 Around 1750cm -1 ~2050cm -1Compared to the other ranges, the two ranges around this appear to have many areas where the difference in signal intensity between the sample solution and the solvent spectrum data is large (the characteristics of the components being analyzed are well represented), so these two ranges were designated as target wavelength range 1 and target wavelength range 2, respectively (Figure 2: Step 102).

[0028] Next, the signal intensity in each of the target wavelength range 1 and the target wavelength range 2 is evaluated (FIG. 2: step 103).

[0029] For target wavelength range 1, the maximum signal intensity of the sample solution reaches near the detection limit (within the specified reference range), so it can be determined that there is no need to improve the signal intensity of the sample solution. Therefore, the spectral data of the sample solution and the spectral data of the solvent acquired in the spectrum measurement in step 101 are set as "condition-compliant spectral data for target wavelength range 1" (Figure 2: step 104).

[0030] On the other hand, for target wavelength range 2, there is a difference of several tens of percent between the detection limit intensity and the maximum signal intensity of the sample solution (below the lower limit of the specified reference range), suggesting that there is room for improving the signal intensity of the sample solution. Therefore, the condition parameters of the spectrum measurement device 10 are set so that the signal intensity of the sample solution in target wavelength range 2 falls within the reference range (e.g., between 80% and 100% of the detection limit intensity), and spectrum measurements are performed for both the sample solution and the solvent. This results in "condition-compliant spectral data for target wavelength range 2" with high signal intensity in target wavelength range 2 (Figure 2: step 104). Note that the "condition-compliant spectral data for target wavelength range 2" may be saturated in wavelength ranges other than target wavelength range 2 (e.g., target wavelength range 1), but this is not a problem because only the portion of target wavelength range 2 is used in subsequent processing. Rather, what is important in the analysis method of the present invention is to focus on wavelength ranges with low signal intensity levels, such as target wavelength range 2, and to perform spectral measurements that increase signal intensity without considering whether signal intensity is saturated in other wavelength ranges.

[0031] Next, for each of target wavelength ranges 1 and 2, a calculation process is performed to subtract the condition-matching spectral data of the solvent from the condition-matching spectral data of the sample solution, thereby obtaining spectral data of the analyte components in each of target wavelength ranges 1 and 2 (FIG. 2: step 105), as shown in FIG. 4. Note that while FIG. 4 only illustrates the calculation process for target wavelength range 1, calculation process is also performed for target wavelength range 2 using the "condition-matching spectral data for target wavelength range 2" of the sample solution and solvent.

[0032] Next, a synthesis process is performed to connect the spectral data of the target component in each of the target wavelength ranges 1 and 2, and generate virtual spectral data for the target component over the entire measurement wavelength range (FIG. 2: step 106), as shown in the lower part of FIG. 5. The target component is then identified using the generated virtual spectral data (FIG. 2: step 107).

[0033] In the above embodiment, a Raman spectrometer is used as the spectrum measuring device, but the present invention can be similarly applied when an FIIR is used as the spectrum measuring device.

[0034] The above-described example is merely one example of an embodiment of the analysis method according to the present invention. The embodiment of the analysis method according to the present invention is as follows.

[0035] In one embodiment of the analytical method according to the present invention, a spectroscopic measurement device is used, which is configured to perform spectral measurement of the liquid flowing through the flow cell, and includes a flow cell through which a liquid flows, and a light detection unit for detecting the amount of light from the flow cell for each wavelength band. The spectroscopic measurement device includes: a spectrum acquisition step of provisionally setting condition parameters for the spectrum measurement of the spectrum measurement device, performing the spectrum measurement on a sample solution containing an analyte component, and acquiring spectral data of the sample solution; a target wavelength range determination step of determining a target wavelength range in which the spectral data of the analyte component should be acquired based on a difference in signal intensity between the spectral data of the sample solution and the spectral data of the solvent previously acquired after the spectrum acquisition step; a condition-matched spectrum acquisition step of setting the spectral data of the sample solution and the spectral data of the solvent acquired in the spectrum acquisition step as condition-matched spectral data, respectively, when the signal intensity level of the spectral data in the target wavelength range is within a predetermined reference range, and when the signal intensity level of the spectral data in the target wavelength range is outside the predetermined reference range, changing the condition parameters so that the signal intensity level of the spectral data in the target wavelength range is within the reference range, and performing the spectrum measurement on the sample solution again to acquire condition-matched spectral data for the target wavelength range of the sample solution that falls within the reference range, and acquiring condition-matched spectral data for the solvent; and a calculation step of subtracting the condition-matched spectral data of the solvent from the condition-matched spectral data of the sample solution in the target wavelength range to obtain spectral data of the analyte component in the target wavelength range.

[0036] In a first aspect of the above embodiment, the target range determination step is executed two or more times to determine multiple non-overlapping target wavelength ranges, and the condition-matching spectrum acquisition step and the calculation step are executed for each of the multiple determined target wavelength ranges, thereby acquiring spectral data of the analyzed component in each of the multiple target wavelength ranges.

[0037] In the first aspect, the condition-matching spectrum acquisition step can acquire the condition-matching spectra by setting different condition parameters for each of the plurality of target wavelength ranges in the spectrometer. This allows for a greater degree of freedom in selecting the target wavelength ranges, making it possible to use many wavelength ranges for identifying the components to be analyzed, since the spectrometer performs spectrum measurement by setting different condition parameters for each of the target wavelength ranges.

[0038] The first aspect of the present invention further includes a synthesis step of connecting together the spectral data of the target component in each of the plurality of target wavelength ranges to generate a single virtual spectral data set of the target component, thereby obtaining virtual spectral data of the target component in a wide wavelength range and enabling accurate identification of the target component.

[0039] In a second aspect of the above embodiment, in the target range determination step, the target wavelength range is a wavelength range in which a peak exists in the sample spectrum but no peak exists in the solvent spectrum. In such a wavelength range, a characteristic spectrum of the analyte component is likely to appear when calculating the difference between the spectrum of the sample solution and the spectrum of the solvent, which can contribute to improving the accuracy of identifying the analyte component.

[0040] In a third aspect of the above embodiment, the lower limit of the reference range is 80% of the detection limit intensity of the spectrometer, thereby obtaining spectral data with high signal intensity in the target wavelength range of the sample solution by re-measurement, and ultimately obtaining spectral data with high signal intensity in the target wavelength range of the analyzed component.

[0041] In a fourth aspect of the above embodiment, the upper limit of the reference range is 100% of the detection limit intensity of the spectrum measurement device, thereby preventing saturation of the signal intensity within the target wavelength range.

[0042] In a fifth aspect of the above embodiment, the spectrum measurement device is a Raman spectrometer, and the spectrum measurement is performed by periodically executing an exposure operation at regular time intervals, in which the detection unit detects an amount of Raman scattered light per unit time from the flow cell, The condition parameters include an exposure time, which is the length of the unit time in one exposure operation, and the number of integrations, which is the number of exposure operations included in the spectrum measurement.

[0043] In a sixth aspect of the above embodiment, the condition parameters include an intensity of light irradiated onto the flow cell.

[0044] In a seventh aspect of the above embodiment, the condition parameters include the intensity of light irradiated onto the flow cell, and in the condition-matching spectrum acquisition step, the intensity of the light is reduced if the signal intensity of the spectral data exceeds the upper limit of the reference range.

[0045] In an eighth aspect of the above embodiment, the condition parameters include the intensity of light irradiated onto the flow cell, and in the condition-matching spectrum acquisition step, the intensity of the light is increased if the signal intensity of the spectral data is less than the lower limit of the reference range.

[0046] In a ninth aspect of the above embodiment, an eluate from a separation column of a liquid chromatograph is made to flow through the flow cell. In this manner, the analytical method according to the present invention can be applied to an LC system.

[0047] In a tenth aspect of the above embodiment, the substance of the target component is identified based on the spectral data of the target component obtained in the calculation step. [Explanation of symbols]

[0048] 2. Analysis channel 4. Liquid transfer pump 6 injectors 8 Separation column 10 Spectral measurement device 12 Processing unit 14 Display 16 Input Devices

Claims

1. An analytical method for acquiring spectral data of a component to be analyzed using a spectroscopic measurement device that is configured to perform spectral measurement of the liquid flowing through the flow cell, the spectroscopic measurement device comprising a flow cell through which a liquid flows and a light detection unit for detecting the amount of light emitted from the flow cell for each wavelength band, the method comprising: a spectrum acquisition step of provisionally setting condition parameters for the spectrum measurement of the spectrum measurement device, performing the spectrum measurement on a sample solution containing an analyte component, and acquiring spectral data of the sample solution; a target wavelength range determination step of determining a target wavelength range in which the spectral data of the analyte component should be acquired based on a difference in signal intensity between the spectral data of the sample solution and the spectral data of the solvent previously acquired after the spectrum acquisition step; a condition-fit spectrum acquisition step of: when the signal intensity level of the spectral data in the target wavelength range falls within a predetermined reference range, setting the spectral data of the sample solution and the spectral data of the solvent acquired in the spectrum acquisition step as condition-fit spectral data of the sample solution and the solvent, respectively; when the signal intensity level of the spectral data in the target wavelength range falls below the lower limit of the predetermined reference range, changing parameters among the condition parameters that affect the signal intensity level of the spectral data to increase the signal intensity level of the spectral data so that the signal intensity level of the spectral data in the target wavelength range falls within the reference range; and re-performing the spectrum measurement on the sample solution using the changed condition parameters to acquire condition-fit spectral data for the target wavelength range of the sample solution that falls within the reference range, and acquiring condition-fit spectral data for the solvent; and a calculation step of subtracting the condition-matched spectral data of the solvent from the condition-matched spectral data of the sample solution in the target wavelength range, thereby obtaining spectral data of the analyte component in the target wavelength range.

2. 2. The analytical method according to claim 1, wherein the target range determination step is performed two or more times to determine a plurality of non-overlapping target wavelength ranges, and the condition-matching spectrum acquisition step and the calculation step are performed for each of the determined plurality of target wavelength ranges, thereby acquiring spectral data of the target component in each of the plurality of target wavelength ranges.

3. 3. The analysis method according to claim 2, wherein in the condition-matching spectrum acquisition step, different condition parameters are set in the spectrometer for each of the plurality of target wavelength ranges to acquire the plurality of condition-matching spectrum data.

4. 4. The analytical method according to claim 2, further comprising a synthesis step of connecting together the spectral data of the target component in each of the plurality of target wavelength ranges to generate one virtual spectral data of the target component.

5. 5. The analytical method according to claim 1, wherein in the target range determination step, the target wavelength range is a wavelength range in which a peak exists in the spectral data of the sample solution but no peak exists in the spectral data of the solvent.

6. The analytical method according to claim 1 , wherein the lower limit of the predetermined reference range is 80% of the detection limit intensity of the spectrometer.

7. The analytical method according to claim 1 , wherein the upper limit of the predetermined reference range is 100% of the detection limit intensity of the spectrometer.

8. the spectrum measurement device is a Raman spectrometer, and the spectrum measurement is performed by periodically executing an exposure operation at regular time intervals, in which the light detection unit detects the amount of Raman scattered light per unit time from the flow cell; The analysis method according to claim 1 , wherein the condition parameters include an exposure time, which is the length of the unit time in one exposure operation, and an accumulation count, which is the number of exposure operations included in the spectrum measurement.

9. The analytical method according to claim 1 , wherein the condition parameters include an intensity of light irradiated onto the flow cell.

10. the condition parameters include the intensity of light irradiated onto the flow cell; 9. The analysis method according to claim 1, wherein, in the condition-matching spectrum acquisition step, the intensity of the light is reduced if the signal intensity of the spectrum data exceeds an upper limit of the predetermined reference range.

11. the condition parameters include the intensity of light irradiated onto the flow cell; 11. The analysis method according to claim 1, wherein in the condition-matching spectrum acquisition step, the intensity of the light is increased if the signal intensity of the spectral data is less than the lower limit of the predetermined reference range.

12. The analytical method according to claim 1 , wherein an eluate from a separation column of a liquid chromatograph is made to flow through the flow cell.

13. The analytical method according to claim 1 , wherein the substance of the target component is identified based on the spectral data of the target component obtained in the calculation step.

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