Device and method for improving configuration precision of ultra-low concentration toc standard solution

Abstract

The application provides a device and method for improving the configuration precision of an ultra-low concentration TOC standard solution, wherein the device comprises a first liquid inlet pipeline for inputting dilution water, a second liquid inlet pipeline for adding a standard solution to the first liquid inlet pipeline, a mixing part for mixing the dilution water and the standard solution, the standard solution is a 1,4-p-benzoquinone solution, the mixing part is connected to a TOC analyzer and a detector for measuring the concentration of the 1,4-p-benzoquinone solution, and the device further comprises a first correction part for correcting the output value of the standard solution according to the test result of the detector, and a second correction part for correcting and calibrating the TOC analyzer according to the output value of the standard solution after the calibration of the first correction part, the two corrections can eliminate the error of the whole sample preparation system, and the ultra-low concentration TOC detector can be accurately calibrated.

Description

Technical Field

[0001] This invention relates to the field of TOC detection, and more particularly to an apparatus and method for improving the accuracy of preparing ultra-low concentration TOC standard solutions. Background Technology

[0002] Currently, the conventional method for TOC calibration and verification mainly uses high-concentration standard substances. However, for low concentrations, extrapolation is primarily used, leading to larger errors and failing to meet on-site testing requirements. Therefore, a system for manufacturing low-concentration TOC standard solutions is needed. However, the lower the concentration of the standard solution, the greater the influence from the environment and the system.

[0003] Prior art CN119110897A provides a calibration curve solution manufacturing system, a measurement system, and a method for manufacturing calibration curve solutions. It prepares calibration curve solutions with ultra-low concentrations, employs a completely closed sample preparation system to reduce a major source of air pollution, and uses a pump injection process instead of manual sample preparation to reduce the risk of contamination introduced by the equipment. However, it neglects the errors introduced by the accuracy of the sample preparation devices (such as pumps and flow meters) in the system. Furthermore, it only reduces the interference of TOC concentration introduced from the substrate and system piping, as the TOC concentration of glassware (such as volumetric flasks and pipettes) during preparation can also introduce significant contamination, causing deviations in the low-concentration standard solution. The prior patent does not eliminate this contamination. The flow rate of the pump and the deviation of the flow meter in the system can also introduce errors, leading to a deviation between the prepared TOC calibration solution concentration and the theoretical concentration. In TOC curve calibration, deviations in the calibration solution will cause the TOC curve to shift, resulting in errors in the testing of low TOC concentrations. Summary of the Invention

[0004] To address the problems of the prior art, this invention provides an apparatus and method for improving the accuracy of preparing ultra-low concentration TOC standard solutions. By using 1,4-p-benzoquinone as a tracer, the TOC concentration introduced by other carbon contents in the environmental system is eliminated, ensuring the accuracy of the entire calibration solution preparation and achieving precise calibration of the ultra-low concentration TOC analyzer.

[0005] The technical solution adopted is as follows:

[0006] An apparatus for improving the accuracy of preparing ultra-low concentration TOC standard solutions includes a first inlet line for inputting dilution water, a second inlet line for adding standard solution to the first inlet line, and a mixing unit for mixing the dilution water and the standard solution. The standard solution is a 1,4-p-benzoquinone solution. The mixing unit is connected to a TOC analyzer and a detector for measuring the concentration of the 1,4-p-benzoquinone solution. The apparatus also includes a first correction unit for correcting the output value of the standard solution based on the test results of the detector, and a second correction unit for correcting and calibrating the TOC analyzer based on the output value of the standard solution preparation system calibrated by the first correction unit.

[0007] Furthermore, the first correction unit is connected to the detector and the TOC analyzer respectively, and the second correction unit is connected to the TOC analyzer or is located inside the TOC analyzer.

[0008] Furthermore, the second inlet pipe is equipped with a sampling device, which is used to extract standard solution and continuously transport the standard solution to the first inlet pipe for mixing with dilution water; the first inlet pipe is equipped with a flow meter and a regulating valve, which are used to control and monitor the flow rate of the dilution water.

[0009] Furthermore, the mixing section is provided with a mixing outlet, which is equipped with a spiral pipeline to mix the dilution water and the standard solution evenly.

[0010] Furthermore, the detector is an LC-MS / MS (liquid chromatography-mass spectrometry) system; the sample loading device can be a dual-plunger pump.

[0011] Furthermore, the first liquid inlet pipe is connected to a UPW cabinet that can provide dilution water, which is ultrapure water.

[0012] A method for improving the accuracy of preparing ultra-low concentration TOC standard solutions, characterized by the following steps: Step 1, dilution water is introduced into the first inlet pipe, and a standard solution of 1,4-p-benzoquinone is introduced into the second inlet pipe; the dilution water and the 1,4-p-benzoquinone standard solution are uniformly mixed in the mixing section; Step 2, the mixing section transmits the mixed 1,4-p-benzoquinone solution of a specific concentration to the detector through the mixing outlet; the detector analyzes the 1,4-p-benzoquinone solution to obtain the actual organic carbon concentration in the 1,4-p-benzoquinone solution (output value 1); Step 3, the first correction section obtains the calibrated organic carbon concentration of the 1,4-p-benzoquinone solution (output value 2) based on output value 1 and the theoretical organic carbon concentration of the 1,4-p-benzoquinone solution; Step 4, the mixing section transmits the mixed 1,4-p-benzoquinone solution of a specific concentration to the TOC analyzer through the mixing outlet; the TOC analyzer measures the 1,4-p-benzoquinone solution to obtain output value 3; Step 5, the second correction section obtains the calibrated TOC concentration value based on output value 2 and output value 3.

[0013] Furthermore, step 1 requires the preparation of at least two sets of standard solutions with different concentrations; step 4 requires the addition of a set of dilution water without the input of standard solutions as a control group.

[0014] Furthermore, in step 3, the first correction unit establishes a calibration curve with output value 1 as the Y-axis and the theoretical organic carbon concentration of the 1,4-p-benzoquinone solution as the X-axis, and obtains the calibrated organic carbon concentration of the 1,4-p-benzoquinone solution (output value 2) through curve calibration; in step 5, a calibration curve is established with output value 3 as the Y-axis and output value 2 as the X-axis, and the TOC concentration after eliminating the error is finally obtained through curve calibration.

[0015] Furthermore, the liquid inlet speed of the UPW cabinet is adjusted by controlling the regulating valve and flow meter, the injection speed of the standard solution is controlled by the sample addition device, and standard solutions of different concentrations are prepared by controlling the injection speed of dilution water and standard solution.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention discloses an apparatus and method for improving the accuracy of preparing ultra-low concentration TOC standard solutions. Using 1,4-p-benzoquinone as a tracer, it eliminates the TOC concentration introduced by other carbon content in the environmental system. The accuracy of the standard solutions obtained by the preparation system is verified and calibrated using LC-MS / MS (liquid chromatography-mass spectrometry). This method can eliminate errors introduced by the entire sample preparation system (such as device metrological accuracy and contamination introduced by the substrate and pipelines), avoid TOC concentration introduced by the diluent and system pipelines, and verify and calibrate the entire preparation system, ensuring the accuracy of the entire calibration solution preparation. This achieves direct and accurate calibration of the ultra-low concentration TOC analyzer. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the device of the present invention;

[0019] Figure 2 This is a calibration curve diagram of the first correction unit in the embodiment;

[0020] Figure 3 This is a calibration curve diagram of the second correction unit in the embodiment;

[0021] The components include: first inlet pipe 1, standard solution 2, mixing unit 3, mixing outlet 301, TOC analyzer 4, detector 5, first correction unit 6, second correction unit 7, sample dispensing device 8, flow meter 9, regulating valve 10, and second inlet pipe 11. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] refer to Figure 1 An apparatus for improving the accuracy of preparing ultra-low concentration TOC standard solutions includes a first inlet pipe 1 for inputting dilution water, a second inlet pipe 11 for adding standard solution 2 to the first inlet pipe 1, and a mixing unit 3 for mixing the dilution water and the standard solution. The standard solution 2 is a 1,4-p-benzoquinone solution. The mixing unit 3 is connected to a TOC analyzer 4 and a detector 5 for measuring the concentration of the 1,4-p-benzoquinone solution. The apparatus also includes a first correction unit 6 for correcting the output value of the standard solution based on the test results of the detector, and a second correction unit 7 for correcting and calibrating the TOC analyzer based on the output value of the standard solution preparation system calibrated by the first correction unit.

[0024] The first correction unit 6 is connected to the detector 5 and the TOC analyzer 4 respectively, and the second correction unit 7 is connected to the TOC analyzer 4 or is located inside the TOC analyzer 4.

[0025] The second inlet pipe 11 is equipped with a sample dispensing device 8, which is used to extract standard solution and continuously transport the standard solution to the first inlet pipe for mixing with dilution water. The first inlet pipe is equipped with a flow meter 9 and a regulating valve 10, which are used to control and monitor the flow rate of the dilution water. The ratio of dilution water to standard solution can be adjusted by controlling the flow rate, thereby adjusting the concentration of the standard solution.

[0026] The mixing section 3 is equipped with a mixing outlet 301, which has a spiral conduit to mix the dilution water and the standard solution evenly. The detector is an LC-MS / MS (Liquid Chromatography-Mass Spectrometry) instrument, which can achieve efficient separation and accurate detection of complex organic samples, and can accurately detect the concentration of 1,4-p-benzoquinone in the standard solution; preferably, the sample loading device can use a dual-plunger pump to ensure a continuous and stable delivery rate.

[0027] The first inlet pipe is connected to the UPW cabinet that provides dilution water. Preferably, the dilution water is TOC ultrapure water, such as at least a portion of the ultrapure water supplied to the point of use from an ultrapure water manufacturing system equipped with a pretreatment device, a primary pure water manufacturing device and a secondary pure water manufacturing device (subsystem), or ultrapure water stored in a designated storage tank.

[0028] The TOC analyzer 4 is a device for measuring the total organic carbon concentration of a liquid being analyzed. The TOC analyzer 4 has the function of decomposing organic matter in the supplied liquid and outputting the conductivity and resistivity values ​​before and after decomposition as response values. Furthermore, the TOC analyzer 4 has the function of calculating a calibration curve of the total organic carbon concentration based on the difference between the response values ​​(output values).

[0029] refer to Figure 2 , 3 The present invention also provides a method for improving the accuracy of preparing ultra-low concentration TOC standard solutions, comprising the following steps:

[0030] Step 1: Diluent water is introduced into the first inlet line, and 1,4-p-benzoquinone standard solution is introduced into the second inlet line. The diluent water and 1,4-p-benzoquinone standard solution are mixed evenly in the mixing section. At least two sets of standard solutions with different concentrations need to be prepared. The inlet speed of the UPW cabinet can be adjusted by controlling the regulating valve and flow meter, and the injection speed of the standard solution can be controlled by the sample addition device. By controlling the injection speed of diluent water and standard solution, standard solutions of different concentrations can be prepared.

[0031] Step 2: The mixing unit transmits the mixed 1,4-p-benzoquinone solution of a specific concentration to the detector through the mixing outlet. The detector analyzes the 1,4-p-benzoquinone solution to obtain the actual organic carbon concentration of the 1,4-p-benzoquinone solution (output value 1).

[0032] Step 3: The first correction unit corrects the output value 1 in step 2. A calibration curve is established with the output value 1 as the Y-axis and the theoretical 1,4-p-benzoquinone solution concentration as the X-axis. The curve is plotted at two or more points. The organic carbon concentration of the calibrated 1,4-p-benzoquinone solution (output value 2) is obtained through curve calibration.

[0033] Step 4: The mixing unit transfers the mixed 1,4-p-benzoquinone solution of a specific concentration to the TOC analyzer through the mixing outlet. The TOC analyzer measures the 1,4-p-benzoquinone solution and obtains an output value of 3. Preferably, a set of dilution water without the input standard solution is also added as a control group so that the TOC analyzer can perform the measurement.

[0034] Step 5: Establish a calibration curve with output value 3 as the Y-axis and output value 2 as the X-axis. The TOC concentration after eliminating errors is finally obtained through curve calibration.

[0035] The following is an example illustrating this:

[0036] 1. The flow rate of the UPW cabinet is controlled at 10 ml / min via a regulating valve and flow meter. A 1,4-benzoquinone solution with a concentration of 1000 ppb-C is used as the standard solution. The solution is injected at different rates, such as 5, 20, and 40 μl / min, and mixed with dilution water in the mixing section via a sample addition device. After passing through the mixing outlet, standard solutions of 0.5 ppb-C, 2 ppb-C, and 4 ppb-C are obtained. It should be noted that since this patent is for calibrating the concentration of organic carbon, the concentration of the 1,4-benzoquinone solution is converted to the concentration of organic carbon in the 1,4-benzoquinone solution during solution preparation to facilitate subsequent calibration without the need for further concentration and unit conversion.

[0037] 2. The actual organic carbon concentration (output value 1) of the 1,4-benzoquinone solution was detected by an LC-MS / MS analyzer. The data table below shows the LC-MS / MS measured concentration (output value 1) and the theoretical concentration of the prepared system:

[0038] Serial Number Configure the system's theoretical concentration, ppb-C LC-MS / MS test concentration (output value 1), ppb-C 1 0.5 0.53 2 2 2.05 3 4 4.06

[0039] 3. Establish a calibration curve with output value 1 as the Y-axis and the theoretical 1,4-p-benzoquinone solution organic carbon concentration as the X-axis. Connect the three points from the three data points in the table to form a straight line, and obtain the calibration curve graph, as shown below. Figure 2 The theoretical relationship between the organic carbon concentration (x) of the 1,4-benzoquinone solution and the output value 1 (y) is y = 1.0084x + 0.0285 (R0). 2 =1), using this calibration formula as the standard, substitute the theoretical organic carbon concentration of the 1,4-p-benzoquinone solution into the calibration formula to obtain the calibrated concentration of the 1,4-p-benzoquinone solution (output value 2). The data table of the system's theoretical concentration and the system's calibrated TOC value (output value 2) is as follows:

[0040] Serial Number Configure the system's theoretical concentration, ppb-C TOC value after system calibration (output value 2), ppb-C 1 0.5 0.5327 2 2 2.0453 3 4 4.0621

[0041] Output value 2 is the concentration of organic carbon in the calibrated standard solution, which is the theoretical TOC value. It can eliminate errors introduced by the entire sample preparation system (such as device measurement accuracy and contamination introduced by the substrate and pipeline).

[0042] 4. Simultaneously, the three sets of standard solutions of the same concentration were transferred to the TOC analyzer through the mixing outlet. As a preferred method, a control group containing only dilution water was added. The TOC analyzer measured the 1,4-p-benzoquinone solution and obtained output value 3. The data table of TOC value (output value 2) and TOC analyzer output value (output value 3) after system calibration is as follows:

[0043] Serial Number TOC value after system calibration (output value 2), ppb-C TOC analyzer output value (output value 3), ppb-C 0 dilution water 0.725 1 0.5327 1.192 2 2.0453 2.678 3 4.0621 4.744

[0044] A calibration curve is created using output value 3 as the Y-axis and output value 2 as the X-axis. A straight line is drawn connecting the four data points in the table to obtain the curve graph, as shown below. Figure 3 The relationship between output value 2 (x) and output value 3 (y) is y = 0.9935x + 0.6856 (R²). 2 =0.9996). According to the standard addition method, the TOC value of the dilution water is C0 = -b / k = 0.69 ppb. Substituting the background value of the dilution water into the TOC spiking concentration, the actual TOC concentration of the system effluent is obtained. Using this calibration coefficient, the input value 3 is substituted into the calibration coefficient to obtain the calibrated TOC concentration value.

[0045] Serial Number TOC value after system calibration (output value 2), ppb-C TOC analyzer output value (output value 3), ppb-C TOC analyzer calibrated concentration value (output value 4), ppb-C 0 dilution water 0.725 0.69 1 0.5327 1.192 1.186 2 2.0453 2.678 2.66 3 4.0621 4.744 4.713

[0046] Based on the output values ​​of the TOC analyzer before and after calibration with standard samples of different concentrations (output value 3, output value 4), after subtracting the background of dilution water, the concentration error of the TOC analyzer before and after calibration with that of the TOC standard samples after spiking (output value 5, output value 6) can be compared, and it can be seen that the error of the TOC analyzer is reduced after calibration.

[0047] Serial Number TOC value after system calibration (output value 2), ppb-C TOC output value before calibration (output value 5), ppb-C TOC output value after calibration (output value 6), ppb-C 0 0.5327 0.463 0.496 1 2.0453 1.953 1.97 2 4.0621 4.016 4.023

[0048] Both calibration formulas mentioned above use the least squares method for linear regression, which is a method in the existing technology and will not be elaborated here.

[0049] 1,4-P-benzoquinone has several advantages as a standard substance. First, it has a benzene ring and is present in very small amounts in the environment, effectively eliminating interference from carbon dioxide and other carbon sources. Second, 1,4-P-benzoquinone is a representative, non-oxidizable standard for TOC determination and can be used as a standard for TOC measurement. Third, 1,4-P-benzoquinone is a standard substance that meets all detection principles (such as direct conductivity, membrane conductivity, and combustion methods) for TOC analyzers (while other substances are insufficient; for example, KHP cannot meet the requirements of direct conductivity TOC testing, which is mainly used in low-concentration TOC analyzers in the semiconductor industry; urea cannot be completely detected by some TOC analyzers). Fourth, 1,4-P-benzoquinone is relatively stable and can be effectively used as a tracer.

[0050] In conventional TOC calibration, organic carbon from any source (airborne pollutants, leaching from containers, background levels in water) is included in the calculation, introducing positive errors. This invention uses 1,4-p-benzoquinone as the sole, specific carbon source. During validation using an LC-MS / MS analyzer, the instrument only identifies and quantifies ion fragments with a specific mass-to-charge ratio of 1,4-p-benzoquinone. Other non-target organic compounds in the environment (such as plasticizers, cleaning agent residues, etc.) are not detected, thus eliminating the direct impact of background pollution on concentration accuracy and obtaining more accurate TOC data. This data is then used as a standard to calibrate the TOC analyzer, reducing calibration errors for low-concentration TOC.

Claims

1. A method for improving the accuracy of preparing ultra-low concentration TOC standard solutions, characterized in that: Includes the following steps, Step 1: Diluent water is introduced into the first inlet line, and a standard solution of 1,4-p-benzoquinone is introduced into the second inlet line. The diluent water and the standard solution of 1,4-p-benzoquinone are mixed evenly in the mixing section. Step 2: The mixing unit transmits a 1,4-p-benzoquinone solution of a specific concentration after mixing to the detector through the mixing outlet. The detector analyzes the 1,4-p-benzoquinone solution to obtain the actual organic carbon concentration in the 1,4-p-benzoquinone solution as the output value 1. Step 3: The first correction unit calculates the calibrated organic carbon concentration of the 1,4-p-benzoquinone solution as output value 2 based on output value 1 and the theoretical organic carbon concentration of the 1,4-p-benzoquinone solution. Step 4: The mixing unit transfers the mixed 1,4-p-benzoquinone solution of a specific concentration to the TOC analyzer through the mixing outlet. The TOC analyzer measures the 1,4-p-benzoquinone solution and obtains the output value 3. Step 5: The second correction unit obtains the calibrated TOC concentration value based on output value 2 and output value 3. In step 3, the first correction unit establishes a calibration curve with output value 1 as the Y-axis and the theoretical organic carbon concentration of the 1,4-p-benzoquinone solution as the X-axis, and obtains the calibrated output value 2 through curve calibration. In step 5, a calibration curve is established with output value 3 as the Y-axis and output value 2 as the X-axis, and the TOC concentration after eliminating the error is finally obtained through curve calibration.

2. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 1, characterized in that: Step 1 requires preparing at least two sets of standard solutions with different concentrations; Step 4 requires adding a set of dilution water without standard solutions as a control group.

3. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 1, comprising a first inlet pipe (1) for inputting dilution water, a second inlet pipe (11) for adding standard solution (2) to the first inlet pipe (1), and a mixing section (3) for mixing dilution water and standard solution, characterized in that: The standard solution (2) is a 1,4-p-benzoquinone solution. The mixing unit (3) is connected to a TOC analyzer (4) and a detector (5) for measuring the concentration of the 1,4-p-benzoquinone solution. It also includes a first correction unit (6) that corrects the output value of the standard solution based on the test results of the detector. The second correction unit (7) corrects and calibrates the TOC analyzer based on the output value of the standard solution calibrated by the first correction unit.

4. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 3, characterized in that: The first correction unit (6) is connected to the detector (5) and the TOC analyzer (4) respectively, and the second correction unit (7) is connected to the TOC analyzer (4) or is located inside the TOC analyzer (4).

5. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 3, characterized in that: The second inlet pipe (11) is equipped with a sample dispensing device (8), which is used to extract standard solution and continuously transport the standard solution to the first inlet pipe for mixing with dilution water.

6. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 3, characterized in that: The mixing section (3) is provided with a mixing outlet (301), which is provided with a spiral pipeline to mix the dilution water and the standard solution evenly.

7. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 5, characterized in that: The detector is an LC-MS / MS liquid chromatography-mass spectrometry system; the sample loading device can be a dual-plunger pump.

8. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 3, characterized in that: The first liquid inlet pipe is connected to a UPW cabinet that can provide dilution water, which is ultrapure water.

9. The method for improving the preparation accuracy of ultra-low concentration TOC standard solutions as described in claim 8, characterized in that: The first liquid inlet pipeline is equipped with a flow meter (9) and a regulating valve (10). The flow meter and regulating valve are used to control and monitor the flow rate of the dilution water. The liquid inlet speed of the UPW cabinet is adjusted by controlling the regulating valve and the flow meter. The injection speed of the standard solution is controlled by the sample addition device. Standard solutions of different concentrations are prepared by controlling the injection speed of the dilution water and the standard solution.

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