Analysis device and gain adjustment device

Abstract

The invention provides an analysis apparatus and a gain adjustment apparatus. An analysis device includes: a photomultiplier that detects fluorescence generated from a sample; and a gain adjusting device for adjusting the gain of the photomultiplier. The gain adjustment device includes: an acquisition unit that acquires a detection value of fluorescence based on a photoelectron multiplier; a power supply unit that supplies power to the photomultiplier; and a power supply control unit that controls the power supply unit on the basis of the detection value acquired by the acquisition unit, thereby adjusting the gain of the photomultiplier tube in the primary analysis of the sample.

Description

Technical Field

[0001] The present invention relates to an analysis device and a gain adjustment device, and in particular to a gain adjustment device for adjusting the gain of a fluorescence detector and an analysis device comprising the gain adjustment device. Background Art

[0002] As a detector used in high-speed liquid chromatographs, there is a fluorescence detector. A photomultiplier tube used in a fluorescence detector can detect weak light with high sensitivity.

[0003] When the sample concentration is high, the fluorescence intensity becomes stronger, and the output of the photomultiplier tube is sometimes saturated. Therefore, when the sample concentration is high, it is necessary to reduce the gain of the photomultiplier tube to avoid output saturation. On the other hand, when the sample concentration is low, it is necessary to increase the gain of the photomultiplier tube so that the signal caused by the component is not buried by the noise of the electrical system, etc.

[0004] The high-speed liquid chromatograph disclosed in Japanese Patent Publication No. 2020-526770 includes an ultraviolet visible (UV-VIS) detector unit. The detector unit includes a structure for detecting a reference beam that does not pass through a sample in the detector unit. Thus, a change in the intensity of light output from a light source included in the detector unit is obtained. Summary of the invention

[0005] For example, in the impurity analysis performed by a chromatograph, it is necessary to analyze both the high-concentration main component and the low-concentration impurities contained in a sample. However, as described above, when analyzing the high-concentration component, the gain of the photomultiplier tube needs to be reduced, and when analyzing the low-concentration component, the gain of the photomultiplier tube needs to be increased, so these components cannot be analyzed at one time. Therefore, a scheme of sacrificing sensitivity and performing analysis with a low gain setting, or a scheme of changing the gain and performing analysis twice, etc. is adopted.

[0006] An object of the present invention is to provide an analysis device that can obtain appropriate measurement results according to the concentration of a component contained in a sample using a fluorescence detector.

[0007] An analysis device according to one aspect of the present invention includes: a light source for exciting a sample; a photomultiplier tube for detecting fluorescence generated from the sample; and a gain adjustment device for adjusting the gain of the photomultiplier tube. The gain adjustment device includes: an acquisition unit for acquiring a detection value based on the fluorescence of the photomultiplier tube; a power supply unit for supplying power to the photomultiplier tube; and a power control unit for adjusting the gain of the photomultiplier tube in one analysis of the sample by controlling the power supply unit of the photomultiplier tube according to the detection value acquired by the acquisition unit.

[0008] According to another aspect of the present invention, a gain adjustment device is a gain adjustment device for adjusting the gain of a photomultiplier tube, comprising: an acquisition unit for acquiring a detection value of the photomultiplier tube; a power supply unit for supplying power to the photomultiplier tube; and a power supply control unit for adjusting the gain of the photomultiplier tube in a single analysis of a sample by controlling the power supply unit based on the detection value acquired by the acquisition unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is an overall view of the high speed liquid chromatograph according to the present embodiment.

[0010] Figure 2 This is a block diagram of the fluorescence detector and gain adjustment device according to this embodiment.

[0011] Figure 3 It is a graph showing the fluorescence intensity input to the photomultiplier tube.

[0012] Figure 4 is a graph showing the voltage applied to the photomultiplier tube.

[0013] Figure 5 is a graph showing the detection values ​​output from the photomultiplier tube.

[0014] Figure 6 is a graph showing the detected values ​​after correction.

[0015] Figure 7 It is a graph showing the detection values ​​in a state where the high-concentration region is saturated.

[0016] Figure 8 It is a graph showing the detection values ​​in a state where a low-density area is buried in noise. DETAILED DESCRIPTION

[0017] Next, a gain adjustment device and an analysis device including the gain adjustment device according to an embodiment of the present invention will be described with reference to the drawings.

[0018] (1) Overall structure of the device

[0019] Figure 1 1 is an overall view showing a high speed liquid chromatograph 1 according to the present embodiment. The high speed liquid chromatograph 1 includes a solvent supply unit 2, a liquid delivery pump 3, a sample injection device 4, a column 5, a fluorescence detector 6, and a gain adjustment device 7. The high speed liquid chromatograph 1 is an example of an analysis device according to the present invention.

[0020] The solvent supply unit 2 stores solvents such as aqueous solvents and organic solvents. The liquid delivery pump 3 supplies the solvent stored in the solvent supply unit 2 as a mobile phase to the analysis flow path. The sample injection device 4 injects the sample into the solvent supplied to the analysis flow path. The solvent injected with the sample is introduced into the column 5. In the column 5, the components contained in the sample are separated based on the interaction between the mobile phase and the stationary phase. The sample separated in the column 5 is introduced into the fluorescence detector 6 together with the solvent. The fluorescence detector 6 irradiates the sample with excitation light and detects the fluorescence generated from the sample using a photomultiplier tube. The gain adjustment device 7 adjusts the gain of the fluorescence detector 6. In addition, the gain adjustment device 7 corrects the detection value of the fluorescence detector 6 according to the gain of the fluorescence detector 6.

[0021] (2) Structure of fluorescence detector

[0022] Next, refer to Figure 2 The structure of the fluorescence detector 6 is described below. Figure 2 As shown, the fluorescence detector 6 includes a light source 61 , a flow cell 62 , a photomultiplier tube (PMT) 63 , and a current-voltage conversion circuit 64 .

[0023] The light source 61 irradiates the sample with excitation light. A xenon lamp, a deuterium lamp, or the like is used as the light source 61. The excitation light irradiated from the light source 61 is extracted as excitation light having a specific wavelength by a spectrometer (not shown) and irradiated to the sample flowing in the flow cell 62.

[0024] Fluorescence is generated from the sample by irradiating the sample with fluorescence flowing in the flow cell 62 with excitation light. Light of a specific wavelength is selected from the fluorescence generated by the sample by a spectrometer (not shown) and is incident on the photomultiplier tube 63 .

[0025] The photomultiplier tube 63 receives the fluorescence generated from the sample, generates electrons according to the intensity of the light by the photoelectric effect, and amplifies the generated electrons to output the detection value of the sample as an electrical signal.

[0026] The current-voltage conversion circuit 64 converts the current, which is the detection value output from the photomultiplier tube 63 , into a voltage. The detection value of the sample converted into a voltage by the current-voltage conversion circuit 64 is output to the gain adjustment device 7 .

[0027] (3) Structure of gain adjustment device

[0028] Next, refer to Figure 2 The structure of the gain adjustment device 7 is described below. Figure 2As shown, the gain adjustment device 7 includes a division unit 71, an acquisition unit 72, a power supply control unit 73, a power supply unit 74, and a gain calculation unit 75. The division unit 71 and the gain calculation unit 75 constitute a correction unit 70.

[0029] The correction unit 70 inputs the detection value of the sample output from the fluorescence detector 6. The correction unit 70 corrects the input detection value based on the gain value (multiplication factor) of the photomultiplier tube 63. The correction unit 70 outputs the corrected detection value as the measurement value of the sample.

[0030] The acquisition section 72 inputs the corrected detection value output from the correction section 70. The acquisition section 72 supplies the acquired corrected detection value to the power supply control section 73.

[0031] The power supply control unit 73 controls the power supply unit 74. The power supply control unit 73 controls the power supply unit 74 based on the corrected detection value of the sample acquired from the acquisition unit 72. The power supply unit 74 is a high-voltage power supply that supplies electric power to the photomultiplier tube 63.

[0032] When the detected value after correction of the sample is higher than the first threshold value, the power supply control unit 73 provides the power supply unit 74 with an instruction to reduce the voltage applied to the photomultiplier tube 63. For example, the power supply control unit 73 provides the power supply unit 74 with an instruction to reduce a predetermined voltage from the current applied voltage. When the detected value after correction of the sample is lower than the second threshold value, the power supply control unit 73 provides the power supply unit 74 with an instruction to increase the voltage applied to the photomultiplier tube 63. For example, the power supply control unit 73 provides the power supply unit 74 with an instruction to increase a predetermined voltage from the current applied voltage.

[0033] The gain calculation unit 75 obtains the voltage value applied to the photomultiplier tube 63 from the power supply unit 74. The gain calculation unit 75 calculates the gain of the photomultiplier tube 63 based on the voltage value currently supplied by the power supply unit 74. The gain calculation unit 75 stores the relationship between the voltage applied to the photomultiplier tube 63 and the gain of the photomultiplier tube 63 in the form of a table. The gain calculation unit 75 calculates the current gain of the photomultiplier tube 63 based on the stored table. The relationship between the applied voltage and the gain in the photomultiplier tube sometimes has deviations for each product. Therefore, the gain adjustment device 7 of the present embodiment stores a table related to the photomultiplier tube 63 installed in the fluorescence detector 6 in the storage device in advance. In addition, the table can be provided at the time of shipment from the factory, or it can be obtained by measurement in the high-speed liquid chromatograph 1 including the fluorescence detector 6 and the gain adjustment device 7.

[0034] In addition, the gain of the photomultiplier tube can be expressed by the following formula:

[0035] μ=A·V kn

[0036] In the above formula, μ is the gain, V is the applied voltage, and A, k, and n are constants depending on the circuit or the device of the photomultiplier tube.

[0037] The divider 71 obtains the current gain of the photomultiplier tube 63 calculated by the gain calculator 75 and corrects the detection value of the sample based on the obtained gain. In this embodiment, the divider 71 divides the detection value output from the fluorescence detector 6 by the gain to output the corrected detection value.

[0038] (4) Gain adjustment method

[0039] Next, refer to Figure 3 to Figure 8 The gain adjustment method according to this embodiment will be described. Figure 3 The graph SA shown in the figure represents the fluorescence intensity input to the photomultiplier tube 63. The graph SA represents the actual fluorescence intensity generated from the sample in the flow cell 62. The graph SA includes an area C1 representing a high-concentration component contained in the sample, and an area C2 representing a low-concentration component contained in the sample. For example, the area C1 is a detection area for the main component contained in the sample, and the area C2 is a detection area for impurities contained in the sample.

[0040] Region C1 is a region showing a high concentration component, and the fluorescence intensity becomes stronger. Therefore, when the gain of the photomultiplier tube 63 is large, as shown in FIG. Figure 7 As shown in FIG. 1 , the detection value of the photomultiplier tube 63 may be saturated around the region C1. The region C2 is a region representing low-concentration components, and the fluorescence intensity is weak. Therefore, when the gain of the photomultiplier tube 63 is small, as shown in FIG. Figure 8 As shown, the detection value of the photomultiplier tube 63 may be buried by noise NS caused by the electrical system, etc. around the area C2. Therefore, the gain adjustment device 7 of this embodiment adjusts the voltage applied to the photomultiplier tube 63 to prevent the detection value from being saturated or buried by noise.

[0041] Figure 4 The curve SB shown in the figure represents the change of the voltage supplied to the photomultiplier tube 63. That is, the curve SB represents the change of the voltage applied to the photomultiplier tube 63 from the power supply unit 74. In the present embodiment, the power supply unit 74 switches the two-stage voltage V1 and the voltage V2 and supplies them to the photomultiplier tube 63. The photomultiplier tube 63 maintains a high gain by applying the voltage V1, and reduces the gain by applying the voltage V2. The voltage V1 is set to a voltage that can be detected with high sensitivity even with a low concentration component. The voltage V2 is set to a voltage that can be detected even with a high concentration component without saturation.

[0042] exist Figure 3In the graph SA shown in FIG. 1 , the fluorescence intensity TH1 is the intensity of the detection value when the photomultiplier tube 63 outputs the first threshold TH1. In addition, the fluorescence intensity TH2 is the intensity of the detection value when the photomultiplier tube 63 outputs the second threshold TH2.

[0043] like Figure 3 As shown in the graph SA shown in FIG. 1 , at time t1, the detection value exceeds the first threshold value TH1. When the power supply control unit 73 determines that the detection value received from the acquisition unit 72 exceeds the first threshold value TH1, it provides an instruction to reduce the voltage to the power supply unit 74. Figure 4 As shown in FIG. 1 , before time t1, the voltage applied by the power supply unit 74 to the photomultiplier tube 63 is V1. When the detection value exceeds the first threshold value TH1, the power supply control unit 73 sends an instruction to the power supply unit 74 to reduce the voltage from V1 to V2. The width of the reduced voltage can be set by the user.

[0044] like Figure 4 As shown in FIG. 1 , the voltage applied to the photomultiplier tube 63 by the power supply unit 74 does not drop to the voltage V2 instantly at time t1. The applied voltage drops to the voltage V2 after slowly decreasing for a period of time. The reason for this is that the power supply unit 74, which is a high-voltage power source, generally takes time to change the output voltage (for example, a time lag of about 100 milliseconds to 1 second is required).

[0045] like Figure 3 As shown in FIG. 1 , at time t2, the detection value is lower than the second threshold value TH2. When the power supply control unit 73 determines that the detection value received from the acquisition unit 72 is lower than the second threshold value TH2, it provides an instruction to increase the voltage to the power supply unit 74. Figure 4 As shown in FIG. 1 , after time t1, the voltage applied by the power supply unit 74 to the photomultiplier tube 63 is V2. When the detection value is lower than the second threshold value TH2, the power supply control unit 73 sends an instruction to the power supply unit 74 to increase the voltage from V2 to V1. The width of the increased voltage can be set by the user.

[0046] As described above, the power supply unit 74 as a high voltage power supply generally takes time to change the output voltage. Therefore, the voltage applied to the photomultiplier tube 63 by the power supply unit 74 does not instantly rise to the voltage V1 at time t2. The applied voltage rises to the voltage V1 after a period of time.

[0047] Figure 5 The curve SC shown in FIG. 6 shows the change of the detection value output from the photomultiplier tube 63. As shown in the curve SC, the detection value of the region C1 representing the high concentration component is changed. Figure 3The reason for this is that the voltage applied to the photomultiplier tube 63 is reduced to V2 between time t1 and time t2, thereby reducing the gain of the photomultiplier tube 63. As a result, although the detection value of the region C1 representing the high-concentration component is reduced, saturation of the detection value is avoided.

[0048] Figure 6 The curve SD shown in FIG. 7 shows the change of the detection value after correction by the correction unit 70. Figure 5 Compared with the curve SC of FIG. 1 , the detection value in the region C1 representing the high-concentration component is corrected. Figure 6 The curve shown in SD can be restored Figure 3 The shape of the graph SA shown in FIG. Since the correction unit 70 corrects the detection value according to the gain, it is possible to obtain an output signal similar to the case where the gain is assumed to be constant.

[0049] like Figure 3 to Figure 6 As shown in , the region C2 of the low-concentration component contained in the sample obtains a correct detection value by supplying a voltage V1 to the photomultiplier tube 63. That is, by maintaining the gain of the photomultiplier tube 63 high, the low-concentration component is correctly detected without being buried by noise. In addition, the region C1 of the high-concentration component contained in the sample is detected in a non-saturated state by supplying a voltage V2 lower than the voltage V1 to the photomultiplier tube 63. That is, by reducing the gain of the photomultiplier tube 63, the high-concentration component is correctly detected in a non-saturated state. Since the detection value is not saturated, if the actual gain of the photomultiplier tube 63 is known, the correction unit 70 can restore the original fluorescence intensity by using the correction processing.

[0050] In this way, the gain adjustment device 7 of the present embodiment corrects the detection value according to the voltage supplied to the photomultiplier tube 63 by the power supply unit 74. As a result, the detection value as the original analysis result can be correctly restored while changing the gain of the photomultiplier tube 63 in one analysis of the sample. For example, it is also conceivable that the correction unit 70 corrects the detection value based on the timing of the voltage change instruction provided by the power control unit 73 to the power supply unit 74. However, in the case of adopting this method, since a time lag occurs in the change of the voltage applied from the power supply unit 74, the detection value cannot be accurately corrected. In the present embodiment, the actual gain of the photomultiplier tube 63 at each moment is estimated based on the change of the voltage actually supplied from the power supply unit 74, not based on the instruction timing of the voltage change using the power control unit 73, and thereby the detection value is corrected, so that the detection value can be accurately corrected.

[0051] The gain adjustment device 7 of this embodiment adjusts the gain of the photomultiplier tube 63 in one analysis of a sample using the high-speed liquid chromatograph 1. Thus, even for a sample containing high-concentration components and low-concentration components, an analysis result can be obtained by one analysis. Therefore, the dynamic range of the fluorescence detector 6 of this embodiment can be virtually expanded. There is no need to change the gain to perform two analyses as in the past, and the efficiency of the analysis process can be achieved.

[0052] (5) Another Implementation Method

[0053] In the above embodiment, the acquisition unit 72 is configured to input the detection value corrected by the correction unit 70. As another embodiment, the acquisition unit 72 may also input the detection value before correction by the correction unit 70. In the above case, the acquisition unit 72 only needs to be configured to input the output value from the current-voltage conversion circuit 64. The power supply control unit 73 compares the detection value before correction with the threshold value to control the power supply unit 74. In the above case, it is necessary to set the threshold value corresponding to the detection value before correction.

[0054] In the above embodiment, two threshold values, namely the first threshold value TH1 and the second threshold value TH2, are used. As another embodiment, a single threshold value TH may be used. In the above case, the gain of the photomultiplier tube 63 may be reduced when the threshold value TH is exceeded, and the gain of the photomultiplier tube 63 may be increased when the threshold value TH is lowered. However, due to noise and the like, the gain switching frequently occurs when the detection value increases or decreases in a short period of time, so it is preferable to use two threshold values ​​as in the above embodiment.

[0055] In the above embodiment, a high-speed liquid chromatograph is used as an example for explanation. The fluorescence detector 6 and gain adjustment device 7 of this embodiment can also be applied to a gas chromatograph, a mass spectrometer using a secondary electron multiplier, or other types of liquid chromatographs.

[0056] (6) Implementation Method

[0057] It should be understood by those skilled in the art that the multiple exemplary embodiments are specific examples of the following embodiments.

[0058] (Item 1)

[0059] An analysis device according to one embodiment includes:

[0060] Light source, to excite the sample;

[0061] Photomultiplier tube, to detect the sample; and

[0062] A gain adjustment device for adjusting the gain of the photomultiplier tube.

[0063] The gain adjustment device comprises:

[0064] an acquisition unit, which acquires a detection value of the sample based on the photoelectron multiplier tube;

[0065] a power supply unit for supplying power to the photomultiplier tube; and

[0066] The power supply control unit adjusts the gain of the photomultiplier tube in one analysis of the sample by controlling the power supply unit of the photomultiplier tube based on the detection value acquired by the acquisition unit.

[0067] Depending on the concentration of the component contained in the sample, appropriate measurement results can be obtained using a photomultiplier tube.

[0068] (Item 2)

[0069] The analysis device according to item 1, wherein:

[0070] The gain adjustment device

[0071] A correction unit is included, which corrects the detection value output from the photomultiplier tube according to the gain of the photomultiplier tube.

[0072] Since the detection value is corrected according to the gain of the photomultiplier tube, an appropriate measurement result can be obtained.

[0073] (Item 3)

[0074] The analysis device according to item 2, wherein:

[0075] The correction unit

[0076] A gain calculation unit is included, the gain calculation unit acquiring a voltage value supplied to the photomultiplier tube by the power supply unit and calculating a gain of the photomultiplier tube based on the acquired voltage value.

[0077] Since the detection value is corrected based on the voltage supplied from the power supply unit, an appropriate measurement result can be obtained.

[0078] (Item 4)

[0079] The analysis device according to item 1, wherein:

[0080] The power supply control unit

[0081] When the detection value acquired by the acquisition unit exceeds a first threshold, an instruction to reduce the gain of the photomultiplier tube is provided to the power supply unit; when the detection value acquired by the acquisition unit is lower than a second threshold, an instruction to increase the gain of the photomultiplier tube is provided to the power supply unit.

[0082] Frequent voltage changes when the detected value fluctuates can be avoided.

[0083] (Item 5)

[0084] The analysis device according to item 2, wherein:

[0085] The acquisition unit acquires the detection value corrected by the correction unit.

[0086] Based on the corrected detection value, gain adjustment corresponding to the concentration can be performed.

[0087] (Item 6)

[0088] The analysis device according to item 1, wherein:

[0089] The sample having fluorescence luminescence is irradiated with excitation light, and the photomultiplier tube detects the generated fluorescence.

[0090] Make appropriate gain adjustments based on the intensity of fluorescence generated from the sample.

[0091] (Item 7)

[0092] The analysis device according to item 1, wherein:

[0093] The gain adjustment device adjusts the gain of the photomultiplier tube included in the fluorescence detector.

[0094] Capable of detecting components with high sensitivity.

[0095] (Item 8)

[0096] A gain adjustment device according to another embodiment adjusts the gain of a photomultiplier tube, and the gain adjustment device comprises:

[0097] An acquisition unit, which acquires the detection value of the photoelectron multiplier tube;

[0098] a power supply unit for supplying power to the photomultiplier tube; and

[0099] The power supply control unit adjusts the gain of the photomultiplier tube in one analysis of a sample by controlling the power supply unit based on the detection value acquired by the acquisition unit.

[0100] Depending on the concentration of the component contained in the sample, appropriate measurement results can be obtained using a photomultiplier tube.

Claims

1. An analysis device comprising: Light source, to excite the sample; a photomultiplier tube, which detects the fluorescence generated from the specimen; as well as A gain adjustment device for adjusting the gain of the photomultiplier tube. The gain adjustment device comprises: an acquisition unit, which acquires a detection value based on the fluorescence of the photoelectron multiplier tube; a power supply unit for supplying power to the photomultiplier tube; and The power supply control unit adjusts the gain of the photomultiplier tube in one analysis of the sample by controlling the power supply unit of the photomultiplier tube based on the detection value acquired by the acquisition unit.

2. The analysis device according to claim 1, wherein The gain adjustment device A correction unit is included, which corrects the detection value output from the photomultiplier tube according to the gain of the photomultiplier tube.

3. The analysis device according to claim 2, wherein: The correction unit A gain calculation unit is included, the gain calculation unit acquiring a voltage value supplied to the photomultiplier tube by the power supply unit and calculating a gain of the photomultiplier tube based on the acquired voltage value.

4. The analysis device according to claim 1, wherein The power supply control unit When the detection value acquired by the acquisition unit exceeds a first threshold, an instruction to reduce the gain of the photomultiplier tube is provided to the power supply unit; when the detection value acquired by the acquisition unit is lower than a second threshold, an instruction to increase the gain of the photomultiplier tube is provided to the power supply unit.

5. The analysis device according to claim 2, wherein: The acquisition unit acquires the detection value corrected by the correction unit.

6. The analysis device according to claim 1, wherein The sample having fluorescent properties is irradiated with excitation light, and the photomultiplier tube detects the generated fluorescence.

7. The analysis device according to claim 1, wherein The gain adjustment device adjusts the gain of the photomultiplier tube included in the fluorescence detector.

8. A gain adjustment device for adjusting the gain of a photomultiplier tube, the gain adjustment device comprising: An acquisition unit, which acquires the detection value of the photoelectron multiplier tube; A power supply unit for supplying power to the photomultiplier tube; as well as The power supply control unit adjusts the gain of the photomultiplier tube in one analysis of a sample by controlling the power supply unit based on the detection value acquired by the acquisition unit.

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