Concentration measurement method based on multiple standard addition and graphical analysis

Abstract

The invention relates to the technical field of concentration measurement, in particular to a concentration measurement method based on multiple standard addition and graphical analysis, which comprises the following steps: S1, measuring the fluorescence intensity reading F0 of a sample background and the volume V2 of the sample background; and S2, adding a fluorescence enhancer with the volume of V0 into the sample background. S3, measuring the fluorescence intensity reading F1 after the fluorescence enhancer is added into the sample; and calculating the fluorescence intensity F1-F0 generated by the sample. S4, a standard solution with the volume of V1 and the concentration of CD is added into the sample for the (N-1) th time, and N is an integer starting from 2 and is sequentially 2, 3, 4 to positive infinity. S5, measuring the fluorescence intensity reading FN of the sample after the standard solution is added; and calculating the sample concentration CSN according to a formula CSN = # imgabs0 # * # imgabs1 # * CD. And S6, repeating the steps S4 and S5, and recording to obtain the fluorescence intensity and the sample concentration of the sample after each operation. By adopting the technical scheme of the invention, the efficiency and accuracy of single sample measurement can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of concentration measurement, and in particular to a concentration measurement method based on multiple standard additions and graphical analysis. Background Art

[0002] The Standard Addition Method is a quantitative analysis method commonly used in chemical analysis. Its core is to determine the concentration of the target component in the sample by adding a standard substance of known concentration to the sample to be tested.

[0003] The conventional standard addition method operation steps are as follows: Take n samples of volume V, add equal amounts to n volumetric flasks, take standard solutions of known concentrations with different concentration gradients, and add them to the above volumetric flasks respectively. After diluting to the required scale with water, measure the corresponding signal response values ​​respectively. With the concentration of the standard solution as the horizontal coordinate and the signal response value as the vertical coordinate, a straight line with an intercept is obtained. Extend the straight line to intersect with the horizontal coordinate, and the concentration value at the intersection is the concentration of the component to be measured in the sample.

[0004] The advantage of the standard addition method is that it avoids the errors caused by matrix differences and is particularly suitable for the analysis of high-matrix, low-content samples. However, its disadvantages are also obvious, including low test efficiency, delicate operation requirements, potential errors, and high sample consumption.

[0005] In order to simplify the operation steps, especially when the number of samples is small, many officially promulgated analytical standards use the method of single sample single addition of standard substance to measure unknown samples.

[0006] However, the existing technology is prone to measurement errors due to limitations in the precision and accuracy of instruments and equipment, operational precision, etc., and has poor measurement capabilities for "precious samples" with complex quantitative analysis preparation processes (multiple physical and chemical treatments) and limited quantities (such as blood samples, urine samples, etc.). Summary of the invention

[0007] The object of the present invention is to provide a concentration measurement method based on multiple standard additions and graphical analysis to solve at least one technical problem existing in the prior art.

[0008] In order to solve the above technical problems, the present invention provides a concentration measurement method based on multiple standard additions and graphical analysis, comprising the steps of: S1: Measure the fluorescence intensity reading F0 of the sample background and the volume V2 of the sample background.

[0009] Further, the steps include: S2: Add a fluorescence enhancer with a volume of V0 to the sample background.

[0010] Further, the steps include: S3: Measure the fluorescence intensity reading F1 after adding the fluorescence enhancer to the sample; Calculate the fluorescence intensity F1-F0 generated by the sample.

[0011] Further, the steps include: S4: Add a volume of V1 and a concentration of C to the sample for the N-1th time D A standard solution of, where N is an integer starting from 2, then 2, 3, 4 to positive infinity.

[0012] Further, the steps include: S5: Measure the fluorescence intensity reading FN of the sample after adding the standard solution; By formula C SN = × ×C D Calculate the sample concentration C SN .

[0013] Further, the steps include: S6: Repeat steps S4 and S5, and record the fluorescence intensity and sample concentration of the sample after each operation.

[0014] Further, the steps include: S7: Draw a scatter plot with sample concentration as the horizontal axis and fluorescence intensity reading as the vertical axis.

[0015] Further, the steps include: S8: Analyze the correlation coefficient of the data in the scatter plot; If the correlation coefficient r is greater than 0.9995, the measurement result is credible, and step S:9 is executed; If the correlation coefficient r is less than 0.9995, the measurement result is unreliable and the measurement is terminated.

[0016] Further, the steps include: S9: Fit the scattered points into line segments and extend them to intersect with the horizontal axis. The absolute value of the concentration at the intersection is the concentration to be measured in the sample.

[0017] In a second aspect, the present application also discloses a concentration measurement device using the concentration measurement method based on multiple standard additions and graphical analysis.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects: 1. Improve the efficiency and accuracy of single sample measurement. Adding standard solution to a single sample several times is more efficient than measuring multiple samples multiple times.

[0019] 2. Eliminate gross errors caused by filtering operations and improve the accuracy of measurement results. This method can tolerate minor errors in the measurement operation process and has a lower probability of wasting samples.

[0020] 3. Effectively judge the measurement quality. Serious operating errors can be directly observed, and the reliability of the measurement results and whether re-measurement is needed can be judged based on the correlation coefficient value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A specific flow chart of a concentration measurement method based on multiple standard additions and graphical analysis disclosed in the present application; Figure 2 A schematic diagram of the data distribution diagram in the embodiment; Figure 3 It is a local distribution diagram of data scatter points in the embodiment; Figure 4 It is a schematic diagram of the three-dimensional structure of the trace uranium analyzer; Figure 5 It is a schematic diagram of the three-dimensional structure of the sample part and the detection part in a closed state; Figure 6 It is a schematic diagram of the three-dimensional structure of the sample part and the detection part in the open state; Figure 7 It is the display interface of the trace uranium analyzer; Figure 8 for Figure 7 A partial enlarged view of .

[0023] Reference numerals: 1-sample part; 2-detection part; 3-counting part; 4-display part; 5-control part; 6-sample dish; 7-sample tray; 8-track; 9-slider; 10-darkroom; 11-excitation light source; 12-photomultiplier tube; 13-outer shell; 14-claw. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] It should also be noted that the following specific embodiments or specific implementations are a series of optimized settings listed in the present invention to further explain the specific content of the invention, and these settings can be used in combination or in association with each other.

[0028] The present invention is further explained below in conjunction with specific implementation modes.

[0029] The concentration measurement method based on multiple standard additions and graphical analysis disclosed in the present application can be used for any substance that can be detected by fluorescence method. This embodiment takes the ultraviolet fluorescence method for measuring uranium as an example. The sample contains uranium of unknown concentration to be measured, and the standard solution added each time is a uranium standard solution of known concentration.

[0030] like Figure 1 As shown, the present application provides a concentration measurement method based on multiple standard additions and graphical analysis, comprising the steps of: S1: Measure the fluorescence intensity reading F0 of the sample background and the volume V2 of the sample background.

[0031] S2: Add a fluorescence enhancer with a volume of V0 to the sample background.

[0032] S3: Measure the fluorescence intensity reading F1 after adding the fluorescence enhancer to the sample; Calculate the fluorescence intensity F1-F0 generated by the sample.

[0033] S4: Add a volume of V1 and a concentration of C to the sample for the N-1th time Dof uranium standard solution, where N is an integer starting from 2, then 2, 3, 4 to positive infinity.

[0034] S5: Measure the fluorescence intensity reading FN of the sample after adding the uranium standard solution; By formula C SN = × ×C D Calculate the sample concentration C SN .

[0035] S6: Repeat steps S4 and S5, and record the fluorescence intensity and sample concentration of the sample after each operation.

[0036] Further, the steps include: S7: Draw a scatter plot with sample concentration as the horizontal axis and fluorescence intensity reading as the vertical axis.

[0037] Further, the steps include: S8: Analyze the correlation coefficient of the data in the scatter plot; If the correlation coefficient r is greater than 0.9995, the measurement result is credible, and step S:9 is executed; If the correlation coefficient r is less than 0.9995, the measurement result is unreliable and the measurement is terminated.

[0038] Further, the steps include: S9: Fit the scattered points into line segments and extend them until they intersect with the horizontal axis. The absolute value of the concentration at the intersection is the uranium concentration to be measured in the sample.

[0039] like Figure 2 As shown, in this embodiment, the value of N is 2-4, and the slope with smaller error is obtained by statistically calculating the four data F1, F2, F3 and F4. The statistical algorithm selected in this application adopts the existing technology, including but not limited to average value, elimination of gross errors, linear regression, etc.

[0040] like Figure 3 As shown, on the way R 2 The value of represents the correlation of the four data and can be used to quantitatively evaluate the quality of the measurement data. 2 That is, the square of the correlation coefficient r, 2 =0.9589 corresponds to r=0.9792. In step S9 of the present application, it is stipulated that r is greater than 0.9995 (i.e. R 2 >0.999), it indicates that the result is reliable, otherwise it indicates that the measurement error is serious.

[0041] This application calculates the sample concentration C SNThe formula is derived from the following formula. For each addition of uranium standard solution, the uranium content added can be expressed as C D ×V1. When N=2, the concentration change value D= The slope K of the graph reflects the quantitative relationship between the concentration change and the reading value under the current environment. The formula is K From the definition of slope, we know that F1-F0=C S K. Substituting K into the formula, we get F1-F0=C S × After sorting out the formula and substituting it into the formula of D, we get C S = × ×C D When N is other values, the formula C is derived based on the corresponding uranium content. SN = × ×C D .

[0042] Compared with the prior art, the present application adopts the method of adding uranium standard solution multiple times to obtain multiple measurement values. The following content describes the prior art by taking the ultraviolet fluorescence method for measuring uranium as an example. The basic principle of the ultraviolet fluorescence method for measuring uranium is that in a liquid sample, uranyl ions can generate a single complex with high fluorescence efficiency and prolonged fluorescence decay life under the action of a uranium fluorescence enhancer. This complex generates fluorescence under the irradiation of a light source such as ultraviolet light, and its fluorescence intensity is proportional to the uranium concentration in the sample. Based on this, the uranium concentration in the sample can be obtained by measuring the fluorescence intensity.

[0043] The industry standard "EJ / T823-2016 Fluorescence Trace Uranium Analyzer" issued by the State Administration of Science, Technology and Industry for National Defense mainly sets requirements for the equipment, technical indicators and inspection methods for ultraviolet fluorescence uranium measurement. The national environmental protection standard "HJ840-2017 Analysis Method for Trace Uranium in Environmental Samples" issued by the Ministry of Environmental Protection sets requirements for specific analysis methods.

[0044] The disadvantage of the UV fluorescence method for measuring uranium is that the fluorescence intensity is greatly affected by the ambient temperature, so the standard addition method is generally used for measurement and analysis. This method can generally complete the analysis of the sample within 10 minutes, during which the temperature generally does not change dramatically, so the influence of temperature can be ignored.

[0045] The formula for measuring uranium concentration by the standard addition method is C S = × ×C D, where F0 is the fluorescence intensity reading of the sample background, F1 is the fluorescence intensity reading after adding uranium fluorescence enhancer to the sample, F2 is the fluorescence intensity reading after adding uranium standard solution to the sample, V1 is the volume of the added uranium standard solution, V2 is the sample volume, and V0 is the volume of the added fluorescence enhancer.

[0046] This formula ignores certain influencing factors, so there is an inherent error within the full range. For this reason, the measurement accuracy error allowed in the industry standard is relatively large (no more than ±10%), and the accuracy assessment standard is only at a certain point (4ng / mL sample).

[0047] By using this calculation with simulated data, it can be found that the higher the concentration of the uranium standard solution, the smaller the error in the measurement result; the higher the concentration of the sample, the larger the calculation error.

[0048] From the above description of the prior art, it can be seen that the prior art has three obvious problems: 1. The selection of uranium standard solution concentration is rather complicated.

[0049] According to the recommendations of the standard (HJ840-2017): for low-concentration samples, select 50 μL of uranium standard solution with a concentration of 100 ng / mL; for high-concentration samples, select 50 μL of uranium standard solution with a concentration of 500 ng / mL.

[0050] When faced with samples of unknown concentration, users need to first measure with a 100ng / mL standard solution. If the calculated concentration of the sample is found to be high, it is necessary to switch to a 500ng / mL standard solution and measure again to obtain a more accurate result. For users whose samples are very "precious", the existing technology methods will seriously waste samples.

[0051] In actual testing, users usually choose 1μg / mL high-concentration uranium standard solution and 5μL of liquid addition, striving to complete the measurement in one go within the allowable error range. However, the use of high-concentration uranium standard solution will inevitably be accompanied by a micro-volume of liquid addition, which brings up the next problem.

[0052] 2. Over-reliance on F2 data The accuracy of the F2 data obtained by adding high-concentration, micro-volume uranium standard solution is very dependent on the accuracy of the liquid addition operation. Especially in the case of high-concentration samples, the slope calculated by the F2-F1 value and the amount of liquid added has a small deviation that has a great impact on the slope calculated by the F1-F0 value: if the slope is slightly larger, the calculated result will be smaller; if the slope is slightly smaller, the calculated result will be larger. These deviations are often caused by the inherent precision (repeatability) of the liquid addition tool (micro-volume pipette), which cannot be controlled by the operator.

[0053] The measurement results are discrete, which is the second pain point of the line standard method.

[0054] 3. The “quality” of the measurement results cannot be directly judged Using the three data obtained for calculation, only one calculation result can be obtained. Its quality can only be guaranteed by "equipment meets the standards", "instruments meet the standards", "skilled operation without mistakes", etc. to ensure that the result meets the requirements.

[0055] In view of the shortcomings of the prior art, the present application further improves the standard addition method.

[0056] like Figure 2 The figure shows the distribution of the measured values ​​after adding uranium standard solution three times using a sample of known concentration. In this embodiment, on the basis of obtaining three measured values ​​(F0, F1, F2) by the standard method, the same uranium standard solution is added multiple times to continue to obtain multiple measured values ​​(F3, F4). It should be noted that in order to more intuitively reflect the impact of error data on test accuracy, the distribution state of the measurement points in the figure is exaggerated (the measurement error is artificially increased). The F1 line and the F1 extension line in the figure are the characteristic lines of the sample to be tested. In addition to F1 and F2, two readings of F3 and F4 are obtained. The four data are statistically calculated, and the slope thereof can be used to calculate the sample concentration. By comparing the F12 line (a method commonly used in the prior art), it is found that the error is large. The final concentration result obtained by the statistical algorithm is also better than the result obtained by using the F12 slope, and the discreteness is smaller.

[0057] By adopting the above technical solution, the present invention has the following beneficial effects: (1) By adding uranium standard solution multiple times and measuring the fluorescence intensity, more data points are obtained. Using these data for statistical calculations, such as linear regression, a more accurate slope can be obtained, thereby improving the accuracy of the calculation of sample concentration. This method reduces the error caused by a single measurement or inaccurate addition operation.

[0058] (2) By drawing a scatter plot and analyzing the correlation coefficient, the reliability of the measurement results can be intuitively judged. When the correlation coefficient is greater than 0.9995, the measurement result is considered reliable. This step provides an objective basis for the judgment of the results and avoids relying solely on subjective guarantees of equipment, instruments and operating standards.

[0059] (3) This technical solution processes multiple measurement values ​​through graphical analysis and statistical algorithms, which not only improves the accuracy of the results but also reduces the discreteness of the results, making the measurement results more stable and reliable.

[0060] (4) Although this technical solution is described using the ultraviolet fluorescence method for measuring uranium as an example, its basic principles and methods are also applicable to other situations where concentration measurement is required. It is only necessary to adjust the type and concentration of the fluorescence enhancer and standard solution according to the specific situation.

[0061] Example 2 like Figure 4-6 As shown, this embodiment provides a trace uranium analyzer using the measurement method in Embodiment 1 to solve at least one technical problem existing in the prior art.

[0062] In order to solve the above technical problems, the present application provides a trace uranium analyzer based on multiple standard additions and graphical analysis quality assessment, comprising a sample part 1, a detection part 2 and a counting part 3; The sample part 1 and the detection part 2 are connected so as to be relatively movable; When it is necessary to add reagent to the sample part 1, the sample part 1 is moved to the outside of the detection part 2; After adding a reagent to the sample part 1, the sample part 1 is moved to the inside of the detection part 2, and the fluorescence intensity of the sample part 1 is detected by the detection part 2; The sample part 1 is provided with a counting part 3 , and the counting part 3 is used to count the number of times the sample part 1 moves relative to the detection part 2 .

[0063] like Figure 1 As shown, as a further implementation of this embodiment, it also includes a display unit 4; The display unit 4 is a touch screen, which can be used for display as well as for operating the analyzer.

[0064] like Figure 4 As shown, as a further implementation of this embodiment, it also includes a control unit 5; The display unit 4, the detection unit 2 and the counting unit 3 are all electrically connected to the control unit 5; The control unit 5 is used to receive and process the detection results and counting data of the detection unit 2 and the counting unit 3, and transmit the processed results to the display unit 4. The control unit 5 is also controlled by the display unit 4 to control the operation of the device.

[0065] like Figure 6 As shown, as a further implementation of this embodiment, the sample portion 1 includes a sample dish 6, a sample tray 7 and a tray guide; The sample dish 6 is arranged on the sample tray 7 and is used to contain reagents; One end of the tray guide is fixedly connected to the sample tray 7; One end of the tray guide rail away from the sample tray 7 is connected to the counting part 3 .

[0066] like Figure 5-6 As shown, as a further implementation of this embodiment, the tray guide rail includes a track 8 and a slider 9, and the slider 9 has the same axial length as the track 8; The slider 9 is fixedly connected to the sample tray 7; One end of the track 8 away from the sample tray 7 is fixedly connected to the counting unit 3; When the reagent is added to the sample part 1, the end of the slider 9 is close to the counting part 3 when the sample part 1 is moved to the inside of the detection part 2; The counting unit 3 and the slider 9 automatically count after the distance reaches a critical distance.

[0067] The critical distance is a preset distance. If the preset distance is 0, it means that the slider 9 needs to abut against the counter before the counter can count. If the preset distance is greater than 0 (for example, 0.5 mm), the distance can be monitored by laser ranging. When it is detected that the distance between the slider 9 and the counter is less than the preset distance, automatic counting is performed.

[0068] like Figure 5-6 As shown, as a further implementation of this embodiment, the detection unit 2 includes a darkroom 10 and a fluorescence detector; After the sample in the sample part 1 enters the dark chamber 10 , the fluorescence intensity of the sample is detected by the fluorescence detector.

[0069] like Figure 5-6 As shown, as a further implementation of this embodiment, the detection unit 2 further includes an excitation light source 11; One end of the excitation light source 11 receives external power supply through a cable, and the other end extends into the darkroom 10 and provides energy to the sample, so that the uranyl ion complex in the sample transitions from the ground state to the high energy state to emit fluorescence of a specific wavelength.

[0070] like Figure 5-6 As shown, as a further implementation of this embodiment, the fluorescence detector is a photomultiplier tube 12, and the photomultiplier tube 12 is arranged on the dark chamber 10 and communicated with the dark chamber 10; When the sample in the darkroom 10 emits fluorescence, the photomultiplier tube 12 receives the fluorescence and converts it into an electrical signal.

[0071] As a further implementation of this embodiment, the control unit 5 is a control circuit including a processor; The control unit 5 matches the measured fluorescence intensity with the counting data, obtains the sample concentration through detection calculation method and graphical representation, and transmits the information to the display unit 4 for display.

[0072] like Figure 4 As shown, as a further implementation of this embodiment, it also includes an outer shell 13; The control unit 5, the detection unit 2 and the counting unit 3 are arranged in the outer shell 13; The display unit 4 is arranged on the outer surface of the outer shell 13; The sample portion 1 is disposed in the outer shell 13 and is taken out when reagents need to be added.

[0073] like Figure 5-6 As shown, as a further implementation of this embodiment, the counting part 3 also includes a travel switch, and the operator touches the display part 4 to transmit the instruction to the control part 5, and the control part 5 controls the travel switch to be opened or closed.

[0074] like Figure 5-6 As shown, as a preferred implementation of this embodiment, the travel switch is an opening and closing claw 14, and the slider 9 is provided with a slot corresponding to the claw 14, and the claw 14 locks and unlocks the slider 9 by cooperating with the slot.

[0075] As a preferred implementation mode of this embodiment, a sensor (not shown in the figure) electrically connected to the counter is provided at the corresponding position of the claw 14 and the slot. When the claw 14 cooperates with the slot, the sensor is triggered and the counter counts once.

[0076] When the analyzer disclosed in the present application is working, the sample part 1 is slid out along the tray rail, the reagent is transferred into the sample dish 6, and then the sample part 1 is slid back along the tray rail, so that the sample dish 6 with the reagent enters the darkroom 10. At this time, the slider 9 triggers the counting part 3 to start automatic counting, and the counting part 3 is preferably a counter, and the counter records the xth measurement (wherein x is a non-zero positive integer, such as 1, 2, 3). After the excitation light source 11 is turned on, the ultraviolet light pulse emitted by the excitation light source 11 excites the reagent to generate fluorescence of a specific wavelength (such as 500nm, 522nm, 546nm). The instrument determines the uranium content in the sample by detecting these fluorescence signals. At this time, the light signal is irradiated on the cathode of the photomultiplier tube 12 to excite photoelectrons. These photoelectrons are accelerated under the action of the electric field and collide with the multiplier electrode to generate more secondary photoelectrons. Through the cascade amplification of multiple multiplication stages, the weak light signal is finally converted into an electrical signal and output to the control part 5. The control unit 5 generates a fluorescence intensity reading Fx by converting the electric signal by counting of the counter.

[0077] like Figure 7-8 Shown is the display and operation interface of the analyzer disclosed in this application during actual use.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A concentration measurement method based on multiple standard additions and graphical analysis, characterized in that: Includes steps: S1: Measure the fluorescence intensity reading F0 of the sample background and the volume V2 of the sample background.

2. The concentration measurement method according to claim 1, characterized in that: Includes steps: S2: Add a fluorescence enhancer with a volume of V0 to the sample background.

3. The concentration measurement method according to claim 1, characterized in that: Includes steps: S3: Measure the fluorescence intensity reading F1 after adding the fluorescence enhancer to the sample; Calculate the fluorescence intensity F1-F0 generated by the sample.

4. The concentration measurement method according to claim 3, characterized in that: Includes steps: S4: Add a volume of V1 and a concentration of C to the sample for the N-1th time D A standard solution of, where N is an integer starting from 2, then 2, 3, 4 to positive infinity.

5. The concentration measurement method according to claim 4, characterized in that: Includes steps: S5: Measure the fluorescence intensity reading FN of the sample after adding the standard solution; By formula C SN = × ×C D Calculate the sample concentration C SN .

6. The concentration measurement method according to claim 5, characterized in that: Includes steps: S6: Repeat steps S4 and S5, and record the fluorescence intensity and sample concentration of the sample after each operation.

7. The concentration measurement method according to claim 6, characterized in that: Includes steps: S7: Draw a scatter plot with sample concentration as the horizontal axis and fluorescence intensity reading as the vertical axis.

8. The concentration measurement method according to claim 7, characterized in that: Includes steps: S8: Analyze the correlation coefficient of the data in the scatter plot; If the correlation coefficient r is greater than 0.9995, the measurement result is credible, and step S9 is executed; If the correlation coefficient r is less than 0.9995, the measurement result is unreliable and the measurement is terminated.

9. The concentration measurement method according to claim 8, characterized in that: Includes steps: S9: Fit the scattered points into line segments and extend them to intersect with the horizontal axis. The absolute value of the concentration at the intersection is the concentration to be measured in the sample.

10. A concentration measuring device using the concentration measuring method based on multiple standard additions and graphical analysis according to any one of claims 1 to 9.

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