Optical measuring device and liquid chromatography system

Abstract

To provide an optical measurement device that can prevent analysis data in an initial stage upon starting an analysis from missing.SOLUTION: An optical measurement device 1 comprises: an optical system unit 2 that includes a measurement cell 12, a light source unit 10, a light reception element 14, and a shutter 18 blocking light bound for the light reception element; a storage unit 6 that stores a measurement value of a dark current of the light reception element; a control unit 4; and a computation unit 8 that subtracts the measurement value of the dark current stored in the storage unit from a value of a current output from the light reception element 14 during analysis and obtains a current value based on intensity of the light the light reception element receives. The optical system unit includes a temperature adjustment element 26, and the control unit is configured to control the temperature adjustment element so as to be a set target temperature, and, when the measurement value of the dark current at the target temperature is not stored in the storage unit right after shifting to a stable state, close the shutter to implement a measurement of the dark current, and the storage unit is configured to store the measurement value of the dark current. The computation unit is configured to keep on using the measurement value of the dark current while the stable state of a temperature of the optical system unit continues.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical measurement device and a liquid chromatography system. Background Art

[0002] As detectors for liquid chromatography, optical measurement devices such as an absorbance detector that measures absorbance are known (see, for example, Patent Document 1). An optical measurement device such as an absorbance detector includes a measurement cell through which a sample flows, a light source that emits light toward the measurement cell, and a light-receiving element such as a photodiode array (hereinafter referred to as PDA) that receives light having passed through the measurement cell and outputs a current having a magnitude corresponding to the intensity of the received light.

[0003] In a light-receiving element such as a PDA, a trace amount of current (dark current) flows even when the element receives no light. Therefore, in order to accurately measure absorbance, it is ideal to subtract the value of dark current at the time of measurement from the value of current output from the light-receiving element at the time of measurement. However, since it is impossible to measure dark current during measurement, conventionally, dark current has been measured immediately before starting measurement and used as the dark current during measurement.

[0004] For example, when an autosampler is included in the configuration of a liquid chromatograph and the operations of the autosampler and the detector are integrally managed, dark current immediately before starting analysis can be measured while preliminary operations such as washing a needle and collecting a sample from a sample vial with the needle are performed in the autosampler. On the other hand, when an autosampler is not included in the configuration of the liquid chromatograph, or the apparatus is not configured such that the operations of the autosampler and the detector can be integrally managed, it has been necessary to measure dark current immediately after analysis is started in order to acquire dark current immediately before the start of absorbance measurement. Prior Art Documents Patent Documents

[0005] Patent Document 1 Japanese Patent Publication No. 2019-184458 [Overview of the project] [Problems that the invention aims to solve]

[0006] Autosamplers are improving in operating speed with each new product development. Measuring the dark current of a detector takes about 7 seconds, but as the operating speed of autosamplers improves and the time required for pre-operation decreases, it is conceivable that in the future, even if one attempts to measure the dark current during the autosampler's pre-operation, the measurement may not be completed in time. In that case, even if one attempts to acquire the dark current just before the analysis starts, the analysis may begin before the dark current measurement is complete, potentially leading to problems such as the loss of initial analysis data. Also, if the dark current is measured immediately after the analysis starts, the initial analysis data will naturally be lost.

[0007] This invention has been made in view of the above problems, and aims to provide an optical measuring device that can prevent the loss of initial analysis data due to the measurement of dark current. [Means for solving the problem]

[0008] The dark current of a photodetector, such as a PDA, has a positive linear relationship with temperature. Therefore, when the temperature of the photodetector changes, the value of the dark current also changes. However, when the photodetector is housed in a common housing along with other optical systems such as a light source and temperature control is performed, the temperature of the photodetector does not change significantly except when the target temperature for temperature control is changed. Even when the temperature of the optical system is controlled, the temperature of the optical system may fluctuate slightly due to changes in ambient temperature, but the range of this fluctuation is about ±1°C from the target temperature. If the temperature of the PDA changes by 1°C, the dark current will fluctuate by about 6.60 (AD value), but this level of dark current fluctuation is very small compared to the absorbance measurement value, and its impact on the analysis results is negligible. Therefore, in this invention, assuming that the temperature of the optical system including the photodetector is controlled, fluctuations in the dark current value due to temperature fluctuations within a range where the temperature of the optical system can be said to be stable are tolerated, while eliminating the need to measure the dark current immediately before or after the start of each analysis.

[0009] In other words, the optical measuring device according to the present invention comprises an optical system section including a measuring cell, a light source section that emits light to be irradiated onto the measuring cell, a photodetector that receives light from the measuring cell and outputs a current corresponding to the intensity of the received light, and a shutter that blocks light from reaching the photodetector; a storage section that stores a measured value of the dark current of the photodetector in the optical system section; a control section for controlling the operation of the optical system section; and a calculation section that performs calculation processing to obtain a current value based on the intensity of light received by the photodetector by subtracting the measured value of the dark current stored in the storage section from the value of the current output from the photodetector during analysis, wherein the optical system section is equipped with a thermometer for adjusting the temperature of the optical system section. The system is equipped with a temperature control element, and the control unit controls the temperature control element so that the temperature of the optical system reaches a set target temperature, and immediately after the system transitions from an unstable state in which the temperature of the optical system fluctuates to a stable state at the target temperature, the system closes the shutter and performs a measurement of the dark current if, at least, a measured value of the dark current at the target temperature has not been stored in the storage unit, the storage unit is configured to store the measured value of the dark current obtained in the measurement, and the calculation unit is configured to continue to use the same measured value of the dark current in the calculation process as long as the stable state of the temperature of the optical system continues.

[0010] Furthermore, the liquid chromatograph system according to the present invention comprises a liquid chromatograph including the optical measuring device described above and a system control unit that controls the liquid chromatograph, wherein the system control unit is configured to set analysis conditions for each of the plurality of analyses and to execute the plurality of analyses consecutively with the analysis conditions set for each after the measurement of the dark current by the optical measuring device is completed, and the calculation unit of the optical measuring device is configured to continue to use the same measured value of the dark current in the calculation process as long as the temperature of the optical system remains stable during the execution of the plurality of analyses. [Effects of the Invention]

[0011] In the optical measuring device according to the present invention, immediately after the temperature of the optical system transitions from a fluctuating state to a stable state, if the measured value of the dark current at the target temperature is not stored in the memory unit, the shutter is closed and the dark current is measured. Subsequently, as long as the stable state of the optical system continues, the same measured value of the dark current is continuously used for calculation processing by the calculation unit. Therefore, even when multiple analyses are performed consecutively, it is not necessary to measure the dark current during the preliminary operation of the autosampler before each analysis starts, or immediately after each analysis starts, thereby preventing the loss of analysis data in the initial stages of the analysis.

[0012] In the liquid chromatography system according to the present invention, since the above-mentioned optical measuring device is included, even when multiple analyses are performed in succession, dark current measurement is not performed during the preliminary operation of the autosampler before each analysis starts, or immediately after the start of each analysis, thereby preventing the loss of analysis data in the initial stages of the analysis. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing one embodiment of an optical measuring device. [Figure 2] This flowchart shows an example of the operation of the same embodiment. [Figure 3] This is a block diagram showing an example of a liquid chromatography system. [Figure 4] This flowchart shows an example of the operation of the same embodiment. [Modes for carrying out the invention]

[0014] Hereinafter, an embodiment of the optical measuring apparatus and liquid chromatograph system according to the present invention will be described with reference to the drawings.

[0015] First, an embodiment of the optical measuring device will be described. As shown in Figure 1, the optical measuring device 1 is an absorbance detector and comprises a spectrometer 2 (optical system section), a control unit 4, a storage unit 6, and a calculation unit 8.

[0016] The spectrometer 2 comprises a light source unit 10, a measurement cell 12, a PDA 14 (light receiving element), a lens 16, a shutter 18, a mirror 20, a slit 22, a grating 24, and a temperature control element 26 all within a common housing.

[0017] The light source unit 10 includes two light sources that emit light having different wavelengths from each other (for example, a D2 lamp and a tungsten lamp), turns on one of the two light sources, and irradiates light toward the measurement cell 12 through which a sample solution flows internally. The lens 16 and the shutter 18 are disposed between the light source unit 10 and the measurement cell 12. The shutter 18 opens and closes on the optical path of light traveling from the light source unit 10 to the measurement cell 12. The mirror 20 is disposed to guide light transmitted through the measurement cell 12 to the grating 24. The slit 22 is provided between the mirror 20 and the grating 24. The grating 24 disperses the light transmitted through the measurement cell 12, which is guided by the mirror 20, for each wavelength band and guides the dispersed light to the PDA 14. The PDA 14 receives light of each wavelength band from the grating 24. The temperature control element 26 is an element for adjusting the temperature of the spectrometer 2 to a set target temperature, and includes, for example, a heater, a fan, a temperature sensor, and the like.

[0018] The control unit 4 controls operations of the light source unit 10, the shutter 18, the temperature control element 26 and the like of the spectrometer 2. The control unit 4 is a function implemented by a computer circuit.

[0019] The storage unit 6 stores dark currents of the PDA 14. The storage unit 6 is a function implemented by a partial storage area of an information storage device such as a flash memory or a hard disk drive.

[0020] The arithmetic unit 8 performs arithmetic processing using signals obtained by the PDA 14. The arithmetic unit 8 is a function implemented by a computer circuit.

[0021] The control unit 4 and the arithmetic unit 8 may be implemented by a common computer circuit, or may be implemented by separate computer circuits.

[0022] The control unit 4 communicates with a system control unit 104 (see FIG. 3) that controls a liquid chromatograph 102 (see FIG. 3) incorporating this optical measurement device 1. The control unit 4 controls the operation of the spectroscope 2 based on information provided from the system control unit 104. The information provided from the system control unit 104 includes a signal related to the light source to be used for absorbance measurement (if the light sources provided in the light source unit 10 are a D2 lamp and a tungsten lamp, it refers to either of these light sources), a signal instructing the start of measurement, a signal instructing the end of measurement, and the like.

[0023] When a plurality of continuous analyses are performed in the liquid chromatograph 102 (see FIG. 3), an analysis method (including analysis conditions such as the type of mobile phase, flow rate, oven temperature, and the type of light source used for absorbance measurement) is set in advance for each analysis, and information related to the optical measurement device 1 among the setting items of the analysis method is provided from the system control unit 104 to the control unit 4. In accordance with the provided information, the control unit 4 lights the light source to be used in the next analysis, and controls the temperature adjustment element 26 such that the temperature of the spectroscope 2 approaches a target temperature corresponding to the light source. The target temperature for temperature adjustment of the spectroscope 2 may be determined by the control unit 4 in accordance with prepared information when information on the type of light source to be used is provided, or the information on the target temperature itself may be directly provided.

[0024] The control unit 4 is configured to start temperature adjustment of the spectroscope 2 in accordance with information from the system control unit 104, and to perform measurement of the dark current of the PDA 14 immediately after the temperature of the spectroscope 2 transitions from an unstable state where the temperature fluctuates toward the target temperature to a stable state where the temperature is stabilized at the target temperature. Whether the temperature of the spectroscope 2 has transitioned from the unstable state to the stable state can be detected based on whether the temperature of the spectroscope 2 has remained within a predetermined temperature range including the target temperature (e.g., target temperature ±1°C) continuously for a predetermined period of time. The dark current measurement is performed by closing the shutter 18 to block light from the light source unit 10.

[0025] The measured values ​​obtained by measuring the dark current are stored in the storage unit 6. The calculation unit 8 subtracts the measured dark current values ​​stored in the storage unit 6 from the current values ​​output from the PDA 14 by the calculation unit 8 during the analysis, and uses the value after the dark current has been subtracted as the signal value for absorbance calculation.

[0026] Here, the memory unit 6 may be configured to store the measured dark current in association with the target temperature of the spectrometer 2. Since the dark current depends on the temperature of the PDA 14, if the target temperature for temperature control of the spectrometer 2 is the same, the dark current value when the temperature of the spectrometer 2 is stable will be approximately the same. Therefore, if the memory unit 6 is configured to store the measured dark current in association with the target temperature of the spectrometer 2, the dark current measurement obtained once can be used in subsequent analyses using the same light source.

[0027] An example of the operation of the optical measuring device 1 will be explained using the flowchart in Figure 2 in conjunction with Figure 1.

[0028] When the optical measuring device 1 is started and information regarding the light source to be used for the first analysis is provided to the control unit 4, the target temperature is determined, and the control unit 4 controls the temperature control element 26 according to the target temperature to start adjusting the temperature of the spectrometer 2 (step 101). The control unit 4 monitors the temperature of the spectrometer 2 and determines whether it is in a stable or unstable state (step 102). While the temperature of the spectrometer 2 is in an unstable state (step 102: No), the control unit 4 outputs an unstable state signal to the system control unit 104 until it becomes stable (step 103).

[0029] After the temperature of the spectrometer 2 has stabilized at the target temperature (Step 102: Yes), the control unit 4 determines whether or not it is necessary to measure the dark current (Step 104). Here, the control unit 4 determines that it is necessary to measure the dark current if, at least, the measured value of the dark current obtained when the spectrometer 2 is in a stable state at the target temperature is not stored in the memory unit 6. For example, after the optical measuring device 1 is started up and before the first analysis is performed, no information regarding the measured value of the dark current is stored in the memory unit 6, so the control unit 4 determines that it is necessary to measure the dark current. On the other hand, if one or more analyses have been performed and the absorbance measurement using the light source to be used in the next analysis has already been performed in a previous analysis, the measured value of the dark current that can be used in the next analysis is stored in the memory unit 6, so it can be determined that it is unnecessary to measure the dark current. At least, if the light source used for measuring absorbance has not been changed since the previous analysis, the temperature of the spectrometer 2 remains stable, so it is not necessary to measure the dark current. This ensures that when multiple analyses are performed consecutively, the dark current is not measured immediately before each analysis or immediately after the start of each analysis. On the other hand, if the light source used for the analysis is changed after one or more analyses have been performed, the target temperature for temperature control of spectrometer 2 will also change. As a result, the temperature of spectrometer 2 will fluctuate towards the new target temperature and become unstable (Step 102: No). When it transitions to a stable state, a decision is made again as to whether or not to perform the dark current measurement (Step 104).

[0030] If the control unit 4 determines in step 104 that it is necessary to measure the dark current, it blocks the light emitted from the light source unit 10 with the shutter 18 of the spectrometer 2 and performs the measurement of the dark current of the PDA 14 (step 105). The measured value of the dark current obtained in this measurement is stored in the storage unit 6. This completes the preparation of the optical measuring device 1 for measurement. Even if the control unit 4 determines in step 104 that it is unnecessary to measure the dark current, the optical measuring device 1 is still prepared for measurement. The control unit 4 may be configured to send a stable state signal to the system control unit 104 (see Figure 3) which controls the liquid chromatograph 102 including the optical measuring device 1, indicating that the temperature of the spectrometer 2 of the optical measuring device 1 has reached a stable state. This allows the system control unit 104 to know whether the optical measuring device 1 is in a state where it can measure, and to send a command to each device to start the analysis at an appropriate time. After the analysis is started, the optical measuring device 1 performs absorbance measurement (step 107).

[0031] In the above embodiment, a decision is made as to whether or not to measure the dark current when the temperature of the spectrometer 2 transitions from an unstable state to a stable state. However, the system may be configured to always measure the dark current immediately after the transition from an unstable state to a stable state without making such a decision.

[0032] Next, an embodiment of a liquid chromatograph system including the optical measuring device 1 described above will be explained.

[0033] The liquid chromatography system 100 comprises a liquid chromatograph 102 and a system control unit 104. In addition to the optical measuring device 1 described above, the liquid chromatograph 102 includes a liquid delivery pump 106, an autosampler 108, and a column oven 110. The system control unit 104 controls the various components of the liquid chromatograph 102 and can be implemented by a computer circuit.

[0034] Although the system control unit 104 is shown in Figure 3 as an element completely separate from the optical measuring device 1, it may be implemented by a computer circuit common to at least a part of the control unit 104, storage unit 106, and arithmetic unit 108 of the optical measuring device 1.

[0035] The system control unit 104 is configured to set the analysis method for each of the multiple analyses based on the information input by the user, and after receiving a command from the user to start the analysis, to execute the multiple analyses sequentially according to the set analysis method.

[0036] Furthermore, the system control unit 104 communicates with the optical measuring device 1, the liquid delivery pump 106, the autosampler 108, and the column oven 110 to determine whether each element is in a usable state, thereby monitoring whether the liquid chromatograph 102 is in a state where it can perform analysis. Whether the optical measuring device 1 is in a usable state is determined by the type of status signal output from the control unit 4 of the optical measuring device 1. If the status signal output from the control unit 4 is an unstable status signal, the optical measuring device 1 is in a usable state; if the status signal output from the control unit 4 is a stable status signal, the optical measuring device 1 is in a usable state.

[0037] The system control unit 104 interrupts the ongoing continuous analysis if the liquid chromatograph 102 becomes unable to perform the analysis between the start and end of the continuous analysis of multiple analyses, and resumes the continuous analysis when the liquid chromatograph 102 returns to a state where it can perform the analysis.

[0038] An example of the operation of the liquid chromatography system 100 will be explained using the flowchart in Figure 4, along with Figure 3.

[0039] After starting the liquid chromatography system 100, the system control unit 104 sets the analysis method for each of the multiple analyses based on the user's input information (step 201). Each component of the liquid chromatograph 102 starts analysis preparation operations such as temperature control according to the information provided by the system control unit 104, and the analysis preparation is complete when all components are ready for analysis (step 202). At this time, a stable state signal is output from the optical measuring device 1 to the system control unit 104. Subsequently, the system control unit 104 performs sequential analysis of the multiple analyses based on the user's instruction to start the analysis (step 203).

[0040] If, for example, the light source used in the optical measuring device 1 is changed during continuous analysis, the temperature of the spectrometer 2 of the optical measuring device 1 becomes unstable and an unstable state signal is output to the system control unit 104 (step 204). The system control unit 104 interrupts the ongoing continuous analysis when the status signal output from the optical measuring device 1 becomes an unstable state signal (step 205). Subsequently, the system control unit 104 resumes the continuous analysis when the status signal output from the optical measuring device 1 becomes a stable state signal again (step 206).

[0041] The embodiments described above are merely examples of the optical measuring apparatus and liquid chromatograph system according to the present invention. Embodiments of the optical measuring apparatus and liquid chromatograph system according to the present invention are as follows.

[0042] In one embodiment of the optical measuring device according to the present invention, An optical system comprising a measuring cell, a light source unit that emits light to be irradiated onto the measuring cell, a light-receiving element that receives light from the measuring cell and outputs a current corresponding to the intensity of the received light, and a shutter that blocks light from reaching the light-receiving element, A storage unit for storing the measured value of the dark current of the light-receiving element in the optical system, A control unit for controlling the operation of the optical system, The system includes a calculation unit that performs calculation processing to obtain a current value based on the intensity of light received by the light-receiving element by subtracting the measured value of the dark current stored in the memory unit from the value of the current output from the light-receiving element during analysis, The optical system section is equipped with a temperature control element for adjusting the temperature of the optical system section. The control unit is configured to control the temperature control element so that the temperature of the optical system reaches a set target temperature, and immediately after transitioning from an unstable state where the temperature of the optical system fluctuates to a stable state at the target temperature, close the shutter and perform a measurement of the dark current if, at least, the measured value of the dark current at the target temperature has not been stored in the storage unit. The storage unit is configured to store the measured values ​​of the dark current obtained in the measurement. The calculation unit is configured to continue using the same measured value of the dark current in the calculation process as long as the temperature of the optical system remains stable.

[0043] In the embodiment [1] described above, the control unit is configured to output a stable state signal indicating that the state has been reached when the temperature of the optical system reaches the target temperature and the measured value of the dark current at the target temperature is stored in the storage unit.

[0044] In embodiment [2] of the above embodiment, the light source unit includes a plurality of light sources, and the target temperature is determined according to the type of light source used. This embodiment [2] can be combined with embodiment [1].

[0045] In embodiment [3] of the above embodiment, the control unit is configured to omit the measurement of the dark current when the temperature of the optical system has transitioned from the unstable state to the stable state at the target temperature and the measured value of the dark current at the target temperature has already been stored in the storage unit. This prevents the measurement of the dark current from being performed unless the target temperature of the optical system is changed, thus preventing the loss of analysis data at the start of the analysis and shortening the waiting time until the analysis can be started. Embodiment [3] can be combined with embodiment [1] and / or embodiment [2].

[0046] In the embodiment [4] described above, the control unit is configured to determine that the temperature of the optical system has transitioned to a stable state at the target temperature when the temperature of the optical system remains within a predetermined range including the target temperature for a predetermined period of time. This embodiment [4] can be combined with embodiments [1], [2], and / or [3] described above.

[0047] One embodiment of the liquid chromatograph system according to the present invention is a liquid chromatograph system comprising a liquid chromatograph including an optical measuring device and a system control unit for controlling the liquid chromatograph, The optical measuring device of the liquid chromatograph is An optical system comprising a measuring cell, a light source unit that emits light to be irradiated onto the measuring cell, a light-receiving element that receives light from the measuring cell and outputs a current corresponding to the intensity of the received light, and a shutter that blocks light from reaching the light-receiving element, A storage unit for storing the measured value of the dark current of the light-receiving element in the optical system, A control unit for controlling the operation of the optical system, The system includes a calculation unit that performs calculation processing to obtain a current value based on the intensity of light received by the light-receiving element by subtracting the measured value of the dark current stored in the memory unit from the value of the current output from the light-receiving element during analysis, The optical system section is equipped with a temperature control element for adjusting the temperature of the optical system section. The control unit is configured to control the temperature control element so that the temperature of the optical system reaches a set target temperature, and immediately after transitioning from an unstable state where the temperature of the optical system fluctuates to a stable state at the target temperature, close the shutter and perform a measurement of the dark current if, at least, the measured value of the dark current at the target temperature has not been stored in the storage unit. The storage unit is configured to store the measured values ​​of the dark current obtained in the measurement. The system control unit is configured to set analysis conditions for each of the multiple analyses, and after the measurement of the dark current by the optical measuring device is completed, to execute the multiple analyses sequentially using the analysis conditions set for each of them. The calculation unit of the optical measuring device is configured to continuously use the same dark current measurement value in the calculation process as long as the temperature of the optical system remains stable during the execution of the multiple analyses.

[0048] In one embodiment of the liquid chromatograph system described above [1], the control unit of the optical measuring device is configured to send an unstable state signal to the system control unit when the temperature of the optical system transitions from a stable state to an unstable state during the plurality of analyses, and when the temperature of the optical system transitions from the unstable state to the stable state, it performs a measurement of the dark current if at least the measured value of the dark current at the current target temperature is not stored in the storage unit, and sends a stable state signal to the system control unit after the measured value of the dark current at the current target temperature is stored in the storage unit, and the system control unit is configured to interrupt the plurality of analyses when it receives the unstable state signal from the control unit while performing the plurality of analyses, and to resume the plurality of analyses when it receives the stable state signal from the control unit while the plurality of analyses are interrupted.

[0049] In the above embodiment [1] of the liquid chromatograph system, the control unit is configured to send the stable state signal to the system control unit immediately after the temperature of the optical system transitions from the unstable state to the stable state, if the measured value of the dark current at the current target temperature is stored in the memory unit when the temperature of the optical system transitions from the unstable state to the stable state during the plurality of analyses. [Explanation of Symbols]

[0050] 1 Optical measuring device 2 Spectrometer (optical system section) 4. Control Unit 6 Memory section 8 Arithmetic section 10 Light source section 12 measuring cells 14. PDA (Photodetector) 16 lenses 18 shutters 20 Mirror 22 slits 24 Gratings 100 Liquid Chromatography Systems 102 Liquid Chromatography 104 System Control Unit 106 Liquid transfer pump 108 Autosampler 110 Column Oven

Claims

1. An optical system comprising a measuring cell, a light source unit that emits light to be irradiated onto the measuring cell, a light-receiving element that receives light from the measuring cell and outputs a current corresponding to the intensity of the received light, and a shutter that blocks light from reaching the light-receiving element, A storage unit for storing the measured value of the dark current of the light-receiving element in the optical system, A control unit for controlling the operation of the optical system, The system includes a calculation unit that performs calculation processing to obtain a current value based on the intensity of light received by the light-receiving element by subtracting the measured value of the dark current stored in the memory unit from the value of the current output from the light-receiving element during analysis, The optical system section is equipped with a temperature control element for adjusting the temperature of the optical system section. The control unit is configured to control the temperature control element so that the temperature of the optical system reaches a set target temperature, and immediately after transitioning from an unstable state where the temperature of the optical system fluctuates to a stable state at the target temperature, close the shutter and perform a measurement of the dark current if, at least, the measured value of the dark current at the target temperature has not been stored in the storage unit. The storage unit is configured to store the measured values ​​of the dark current obtained in the measurement. An optical measuring device wherein the calculation unit is configured to continuously use the same measured value of the dark current in the calculation process as long as the temperature of the optical system remains in a stable state.

2. The optical measuring device according to claim 1, wherein the control unit is configured to output a stable state signal indicating that the optical measuring device has entered the stable state when the temperature of the optical system has stabilized at the target temperature and the measured value of the dark current at the target temperature has been stored in the storage unit.

3. The light source unit includes multiple light sources, The optical measuring apparatus according to claim 1, wherein the target temperature is determined according to the type of light source used.

4. The optical measuring apparatus according to any one of claims 1 to 3, wherein the control unit is configured to omit the measurement of the dark current when the temperature of the optical system has transitioned from the unstable state to the stable state at the target temperature and the measured value of the dark current at the target temperature has already been stored in the storage unit.

5. The optical measuring apparatus according to any one of claims 1 to 3, wherein the control unit is configured to determine that the temperature of the optical system has transitioned to a stable state at the target temperature when the temperature of the optical system remains within a predetermined range including the target temperature for a predetermined period of time.

6. A liquid chromatograph system comprising a liquid chromatograph including an optical measuring device and a system control unit for controlling the liquid chromatograph, The optical measuring device of the liquid chromatograph is An optical system comprising a measuring cell, a light source unit that emits light to be irradiated onto the measuring cell, a light-receiving element that receives light from the measuring cell and outputs a current corresponding to the intensity of the received light, and a shutter that blocks light from reaching the light-receiving element, A storage unit for storing the measured value of the dark current of the light-receiving element in the optical system, A control unit for controlling the operation of the optical system, The system includes a calculation unit that performs calculation processing to obtain a current value based on the intensity of light received by the light-receiving element by subtracting the measured value of the dark current stored in the memory unit from the value of the current output from the light-receiving element during analysis, The optical system section is equipped with a temperature control element for adjusting the temperature of the optical system section. The control unit is configured to control the temperature control element so that the temperature of the optical system reaches a set target temperature, and to close the shutter and perform the dark current measurement only immediately after the optical system transitions from an unstable state where the temperature fluctuates to a stable state at the target temperature. The storage unit stores the measured value of the dark current obtained in the measurement, The system control unit is configured to set analysis conditions for each of the multiple analyses, and after the measurement of the dark current by the optical measuring device is completed, to execute the multiple analyses sequentially using the analysis conditions set for each of them. A liquid chromatograph system in which the calculation unit of the optical measuring device is configured to continuously use the same dark current measurement value in the calculation process as long as the temperature of the optical system remains stable during the execution of the plurality of analyses.

7. The control unit of the optical measuring device is configured to send an unstable state signal to the system control unit when the temperature of the optical system transitions from a stable state to an unstable state during the plurality of analyses, and when the temperature of the optical system transitions from the unstable state to the stable state, it performs a measurement of the dark current if at least the measured value of the dark current at the current target temperature is not stored in the storage unit, and sends a stable state signal to the system control unit after the measured value of the dark current at the current target temperature is stored in the storage unit. The liquid chromatograph system according to claim 6, wherein the system control unit is configured to interrupt the plurality of analyses when it receives the unstable state signal from the control unit while the plurality of analyses are being performed, and to resume the plurality of analyses when it receives the stable state signal from the control unit while the plurality of analyses are interrupted.

8. The liquid chromatograph system according to claim 7, wherein the control unit is configured to send the stable state signal to the system control unit immediately after the temperature of the optical system transitions from the unstable state to the stable state, when the measured value of the dark current at the current target temperature is stored in the storage unit during the plurality of analyses.

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