A quantitative test method for color mutation at titration endpoint based on spectral illumination
Through the spectral illuminance-based testing method, the misjudgment of quantitative test of color mutation in the titration end point and the impact of external factors are solved, and accurate and economical quantitative tests are achieved, which improves the practicality and application scope of the test.
Patent Information
- Application Number
- CN202510046771.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-04-08
AI Technical Summary
The existing quantitative test methods for color mutations at the endpoint of titration have problems such as risk of misjudgment, are greatly affected by external factors, expensive equipment and limited application.
Using a test method based on spectral illuminance, the main wavelength and relative spectrum of the liquid to be tested are measured through a spectral illuminance meter, combined with temperature stability and dropping addition of standard solutions, a marking line chart is drawn to determine the typical characteristics of color mutation at the end of the titration point.
Accurate quantitative test of color mutations at the end point of titration is realized, which reduces the risk of artificial misjudgment, reduces dependence on external factors, reduces equipment costs, and improves the practicality and promotion value of the test.
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Figure CN119779999A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a quantitative testing method for color mutation of titration endpoint based on spectral illumination. Background Art
[0002] As one of the important quantitative analysis methods, titration analysis has been widely used in component testing.
[0003] Manual titration is the mainstream technology in titration analysis at present. It indicates the endpoint of titration by the change of indicator color. The specific operation process of manual titration is: first, add color indicator to the test solution (a few solutions can be used as indicators themselves), then add standard solution through a graduated burette (acid or alkaline), and observe the color change of the reaction solution with human eyes. When the color suddenly changes, it is judged that the titration has reached the endpoint, stop the titration immediately, and visually read the volume of standard solution consumed by the burette.
[0004] As a traditional titration technology, manual titration has a profound theoretical system, with advantages such as intuitiveness, speed, and simplicity. It is also an arbitration test method. However, manual titration also has unavoidable defects: manual titration relies on human eyes to observe the color change of the reaction solution to determine the titration endpoint. On the one hand, it is affected by the experience, psychological and physiological factors of the tester. Everyone has different sensitivity to color, which often leads to misjudgment of those reactions with unclear color mutations; on the other hand, the external climate and light will also affect the judgment of color mutations. Therefore, to ensure the accuracy of the test results, we must first solve the technical problem of how to quantitatively test the color mutation of the titration endpoint intuitively, quickly and easily.
[0005] At present, there are mainly the following quantitative test methods for color mutation at the titration endpoint: (1) Electrochemical titration. It is an analytical method based on the electrical and electrochemical properties of substances and their changes. Among them, potentiometric titration is the most widely used. It is a method for determining the titration endpoint by the sudden jump of electrode potential during the titration process. Its shortcomings are: the selection of specific electrodes for different chemical reaction types, the contact measurement of the exchange of charges between the colloid on the electrode surface and the solution, which has a greater impact on the determination of low-content samples, and is greatly affected by temperature and cannot be measured at high temperatures, signal delay, and difficulty in aligning the titration endpoint with the color endpoint. Therefore, its application range is greatly limited. (2) Temperature titration. It is a titration method based on the temperature change during the reaction process to determine the content of the analyte. Its shortcomings are: it cannot test complex chemical reaction processes that are both exothermic and endothermic, which greatly limits its application range. (3) Photometric titration. The titration endpoint is determined by the change of optical parameters such as absorbance, fluorescence intensity or optical rotation of the test solution using a photometer. Its disadvantages are: since it uses a single wavelength absorbance analysis test, it is not suitable for chemical reactions in which the characteristic absorption wavelength shifts before and after the reaction. When the chemical reaction occurs multiple times with multiple absorption wavelengths, it is impossible to obtain an accurate photometric signal of the titration end point, and its applicability is poor. (4) Color recognition titration. Quantitative analysis of color is achieved through various color recognition technologies. Its disadvantages are: it places high requirements on the measurement accuracy and sensitivity of the test instrument, so the instrument is relatively expensive and its promotion and application are limited.
[0006] In summary, for quantitative testing of color mutation at the titration endpoint, various existing methods have shortcomings, so it is necessary to invent new testing technologies. Summary of the invention
[0007] The invention proposes a quantitative test method for color mutation at titration endpoint based on spectral illumination, which has reasonable design, accurate data, and is practical and convenient. The method can solve the shortcomings of various current methods.
[0008] The technical scheme adopted by the present invention is: a quantitative test method for color mutation of titration endpoint based on spectral illumination, comprising the following steps: (1) regulating the temperature of the test room to keep the temperature stable during the entire test process; (2) using a spectral illumination meter, with its probe vertically downwardly irradiating a test liquid configured according to relevant standards in a beaker or conical flask located in a black box; (3) adding a standard solution configured according to relevant standards in sequence and incrementally through a burette (acidic or alkaline) with a scale; (4) setting the wavelength to 380nm, conducting a test, and determining the main wavelength and relative spectrum effective test data of the test liquid; (5) drawing a marked line graph with the volume of the standard solution added to the test liquid as the horizontal coordinate and the main wavelength or relative spectrum effective test data of the test liquid as the vertical coordinate; (6) using standard powder with a known titration endpoint, according to steps (1)-(5), determining the typical characteristics of the titration endpoint of the marked line graph; (7) testing the sample according to steps (1)-(5), and then determining the titration endpoint of the sample according to the typical characteristics of the titration endpoint of the marked line graph.
[0009] Furthermore, the temperature in step (1) is stable, with the temperature fluctuation not exceeding 5°C.
[0010] Furthermore, the spectral illuminance meter in step (2) has a continuous testing function and can simultaneously test illuminance, dominant wavelength and relative spectrum.
[0011] Furthermore, the black box of step (2) has a black inner surface, an upper surface provided with an illumination hole matching the probe of the spectrophotometer and located directly above the beaker or conical flask, the probe can be inserted into the illumination hole, and a hole is provided on the side for taking in and placing the beaker or conical flask, and the hole is set to ensure that the illumination of the liquid to be tested is 0.1-0.3.
[0012] Furthermore, in the step (2), a color indicator is added to the test solution (a few solutions themselves can be used as indicators).
[0013] Furthermore, the step (4) determines the effective test data of the main wavelength and relative spectrum of the test liquid this time, and is executed according to the following rules: (1) Start the continuous test, and the test data of the first three times are not counted; (2) When the range of the test data of the main wavelength tested for 6 consecutive times is ≤15, stop the test, and record the main wavelength and relative spectrum test data of the last test as the effective test data of the main wavelength and relative spectrum of the test liquid this time; (3) When the range of the test data of the main wavelength tested for 5 consecutive times is ≤15, and the range of the test data of the 6th test is >15, the number of consecutive tests is reduced by 1. (4) When the range of the main wavelength test data for 5 consecutive times is ≤15, and the range of the Nth and N+1th test data is >15, the number of consecutive times is reduced by 1, until the range of the main wavelength test data for 6 consecutive times is ≤15, then the test is stopped and the main wavelength and relative spectrum test data of the last test are recorded as the effective test data of the main wavelength and relative spectrum of the test liquid; (4) When the range of the main wavelength test data for 5 consecutive times is ≤15, and the range of the Nth and N+1th test data is >15, all test data are invalidated and the test is repeated according to the provisions of the above items (2) and (3).
[0014] The beneficial effects of the present invention are as follows: (1) the color mutation is organically linked to light parameters such as illumination, main wavelength and relative spectrum, the system error is small, and the design route is scientific; (2) the titration endpoint color mutation technology has achieved a "qualitative leap" from qualitative testing to quantitative testing, and the accuracy is high; (3) no expensive testing equipment is required, and the required instruments and accessories are easy to purchase and process, which has great promotion value; (4) various shortcomings of the existing methods are solved, and the practicality is strong. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a front view schematic diagram of the present invention.
[0016] Figure 2 It is a cross-sectional schematic diagram of the present invention.
[0017] Figure 3 It is a marked line graph of the standard powder calcium oxide test (EDTA titration method) of the present invention.
[0018] Figure 4 It is a marked line graph of the sample calcium oxide test (EDTA titration method) of the present invention.
[0019] Figure 5 It is a marked line graph of the standard powder magnesium oxide test (EDTA titration subtraction method) of the present invention.
[0020] Figure 6 It is a marked line graph of the sample magnesium oxide test (EDTA titration subtraction method) of the present invention. DETAILED DESCRIPTION
[0021] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims. Embodiment 1
[0022] Reference Figure 1-4 A quantitative test method for color mutation at titration endpoint based on spectral illumination comprises the following steps: (1) regulating the temperature of the test room to keep the temperature stable during the entire test process; (2) using a spectral illumination meter 1, with its probe 2 vertically irradiating downward a test solution 5 located in a black box 7 and contained in a beaker 4 and configured according to the standard GB / T176-2017 "Cement Chemical Analysis Method"; (3) adding a standard solution configured according to the standard GB / T176-2017 "Cement Chemical Analysis Method" in increments in sequence through a graduated acid burette; (4) setting the wavelength to 380 nm, and performing Carry out the test to determine the effective test data of the main wavelength and relative spectrum of the test liquid 5; (5) Draw a marked line graph with the volume of the standard solution added to the test liquid 5 as the horizontal axis and the main wavelength or relative spectrum effective test data of the test liquid 5 as the vertical axis; (6) Using standard powder with known titration end point, draw a marked line graph of the standard powder according to steps (1)-(5) to determine the typical characteristics of the color mutation at the titration end point; (7) Draw a marked line graph of the sample according to steps (1)-(5), and then determine the titration end point of the sample based on the typical characteristics of the color mutation at the titration end point of the marked line graph.
[0023] The temperature in step (1) of this embodiment is stable, and the temperature fluctuation does not exceed 5°C.
[0024] The spectroradiometer 1 in step (2) of this embodiment adopts a dual-color cloud spectrum HP350 spectroradiometer, which has a continuous testing function and can simultaneously test the illumination, main wavelength and relative spectrum.
[0025] The black box 7 in step (2) of this embodiment has a black inner surface and an irradiation hole 3 matched with the spectral illuminance meter probe 2 and located directly above the beaker 4 on the upper surface. The diameter of the irradiation hole is 20 mm, and the probe 2 can be inserted into the irradiation hole 3. A hole 6 is provided on the side for taking in and placing the beaker. The hole is arranged to ensure that the illumination of the liquid to be tested is 0.1-0.3.
[0026] The test solution 5 in step (2) of this embodiment is a calcium oxide solution (EDTA titration method) to which a color indicator calcein-methylthymol blue-phenolphthalein mixed indicator is added.
[0027] The standard solution in step (3) of this embodiment is an EDTA standard titration solution.
[0028] Step (4) of this embodiment determines the effective test data of the main wavelength and relative spectrum of the test liquid this time, and is executed according to the following rules: (1) Start continuous testing, and the test data of the first three times are not counted; (2) When the range of the test data of the main wavelength tested for 6 consecutive times is ≤15, stop the test, and record the main wavelength and relative spectrum test data of the last test as the effective test data of the main wavelength and relative spectrum of the test liquid this time; (3) When the range of the test data of the main wavelength tested for 5 consecutive times is ≤15, and the range of the test data of the 6th test is >15, the number of consecutive tests is reduced by 1. (4) When the range of the main wavelength test data for 5 consecutive times is ≤15, and the range of the Nth and N+1th test data is >15, the number of consecutive times is reduced by 1, until the range of the main wavelength test data for 6 consecutive times is ≤15, then the test is stopped and the main wavelength and relative spectrum test data of the last test are recorded as the effective test data of the main wavelength and relative spectrum of the test liquid; (4) When the range of the main wavelength test data for 5 consecutive times is ≤15, and the range of the Nth and N+1th test data is >15, all test data are invalidated and the test is repeated according to the provisions of the above items (2) and (3).
[0029] The color change in step (6) of this embodiment is that the green fluorescence of the test liquid completely disappears and turns red.
[0030] In step (6) of this embodiment, a volume of 38.5 mL of standard solution is added dropwise to the known endpoint of the titration of the standard powder.
[0031] The typical characteristics of the color mutation at the titration endpoint in step (6) of this embodiment are determined in the following manner: The volume of standard solution added to the standard powder titration endpoint is 38.5 = (A + B) / 2 = (42 + 35) / 2.
[0032] The endpoint of the sample titration in step (7) of this embodiment is determined in the following manner: The volume of standard solution added to the endpoint of sample titration = (A+B) / 2 = (40+33) / 2 = 36.5 mL. Embodiment 2
[0033] Reference Figure 1-4A quantitative test method for color mutation at titration endpoint based on spectral illumination comprises the following steps: (1) regulating the temperature of the test room to keep the temperature stable during the entire test process; (2) using a spectral illumination meter 1, with its probe 2 vertically irradiating downward a test solution 5 located in a black box 7 and contained in a beaker 4 and configured according to the standard GB / T176-2017 "Cement Chemical Analysis Method"; (3) adding a standard solution configured according to the standard GB / T176-2017 "Cement Chemical Analysis Method" in increments in sequence through a graduated acid burette; (4) setting the wavelength to 380 nm, and performing Carry out the test to determine the effective test data of the main wavelength and relative spectrum of the test liquid 5; (5) Draw a marked line graph with the volume of the standard solution added to the test liquid 5 as the horizontal axis and the main wavelength or relative spectrum effective test data of the test liquid 5 as the vertical axis; (6) Using standard powder with known titration end point, draw a marked line graph of the standard powder according to steps (1)-(5) to determine the typical characteristics of the color mutation at the titration end point; (7) Draw a marked line graph of the sample according to steps (1)-(5), and then determine the titration end point of the sample based on the typical characteristics of the color mutation at the titration end point of the marked line graph.
[0034] The temperature in step (1) of this embodiment is stable, and the temperature fluctuation does not exceed 5°C.
[0035] The spectroradiometer 1 in step (2) of this embodiment adopts a dual-color cloud spectrum HP350 spectroradiometer, which has a continuous testing function and can simultaneously test the illumination, main wavelength and relative spectrum.
[0036] The black box 7 in step (2) of this embodiment has a black inner surface and an irradiation hole 3 matched with the spectral illuminance meter probe 2 and located directly above the beaker 4 on the upper surface. The diameter of the irradiation hole is 20 mm, and the probe 2 can be inserted into the irradiation hole 3. A hole 6 is provided on the side for taking in and placing the beaker. The hole is arranged to ensure that the illumination of the liquid to be tested is 0.1-0.3.
[0037] The test solution 5 in step (2) of this embodiment is a magnesium oxide solution (EDTA titration subtraction method) to which a color indicator acid chrome blue K-naphthol green B mixed indicator is added.
[0038] The standard solution in step (3) of this embodiment is an EDTA standard titration solution.
[0039] Step (4) of this embodiment determines the effective test data of the main wavelength and relative spectrum of the test liquid this time, and is executed according to the following rules: (1) Start continuous testing, and the test data of the first three times are not counted; (2) When the range of the test data of the main wavelength tested for 6 consecutive times is ≤15, stop the test, and record the main wavelength and relative spectrum test data of the last test as the effective test data of the main wavelength and relative spectrum of the test liquid this time; (3) When the range of the test data of the main wavelength tested for 5 consecutive times is ≤15, and the range of the test data of the 6th test is >15, the number of consecutive tests is reduced by 1. (4) When the range of the main wavelength test data for 5 consecutive times is ≤15, and the range of the Nth and N+1th test data is >15, the number of consecutive times is reduced by 1, until the range of the main wavelength test data for 6 consecutive times is ≤15, then the test is stopped and the main wavelength and relative spectrum test data of the last test are recorded as the effective test data of the main wavelength and relative spectrum of the test liquid; (4) When the range of the main wavelength test data for 5 consecutive times is ≤15, and the range of the Nth and N+1th test data is >15, all test data are invalidated and the test is repeated according to the provisions of the above items (2) and (3).
[0040] The color change in step (6) of this embodiment is that the test liquid is titrated to pure blue.
[0041] In step (6) of this embodiment, a volume of 39.5 mL of standard solution is added dropwise to the known endpoint of the standard powder titration.
[0042] The typical characteristics of the color mutation at the titration endpoint in step (6) of this embodiment are determined in the following manner: The volume of standard solution added to the standard powder titration endpoint is 39.5 = (A + B) / 2 = (39 + 40) / 2.
[0043] The endpoint of the sample titration in step (7) of this embodiment is determined in the following manner: The volume of standard solution added to the endpoint of sample titration = (A+B) / 2 = (42+43) / 2 = 42.5 mL.
Claims
1. A quantitative test method for color mutation at titration endpoint based on spectral illumination, characterized in that: The method comprises the following steps: (1) regulating the temperature of the test room to keep the temperature stable during the entire test process; (2) using a spectrophotometer, with its probe vertically irradiating downward the test liquid located in a black box and contained in a beaker or a conical flask configured according to relevant standards; (3) adding a standard solution configured according to relevant standards in increments in sequence through a graduated acid or alkaline burette; (4) setting the wavelength to 380 nm, conducting the test, and determining the main wavelength and relative spectrum effective test data of the test liquid; (5) drawing a marked line graph with the volume of the standard solution added to the test liquid as the horizontal coordinate and the main wavelength or relative spectrum effective test data of the test liquid as the vertical coordinate; (6) using standard powder with a known titration end point, according to steps (1) to (5), determining the typical characteristics of the titration end point of the marked line graph; (7) testing the sample according to steps (1) to (5), and then determining the titration end point of the sample based on the typical characteristics of the titration end point of the marked line graph.
2. The quantitative test method for color mutation at titration endpoint based on spectral illumination according to claim 1, characterized in that: The temperature in step (1) is stable, with the temperature fluctuation not exceeding 5°C.
3. The quantitative test method for color mutation at titration endpoint based on spectral illumination according to claim 1, characterized in that: The spectral illuminance meter in step (2) has a continuous testing function and can simultaneously test illuminance, dominant wavelength and relative spectrum.
4. The quantitative test method for color mutation at titration endpoint based on spectral illumination according to claim 1, characterized in that: The black box in step (2) has a black inner surface and an illumination hole on the upper surface that matches the probe of the spectrophotometer and is located directly above the beaker or conical flask. The probe can be inserted into the illumination hole. A hole is provided on the side for placing the beaker or conical flask in and out. The hole is set to ensure that the illumination of the liquid to be tested is 0.1-0.
3.
5. The quantitative test method for color mutation at titration endpoint based on spectral illumination according to claim 1, characterized in that: In the step (2), the test liquid is added with a color indicator, and a small amount of the liquid itself can serve as an indicator.
6. The quantitative test method for color mutation at titration endpoint based on spectral illumination according to claim 1, characterized in that: The step (4) determines the effective test data of the main wavelength and relative spectrum of the test liquid this time, and is executed according to the following rules: (1) Start the continuous test, and the test data of the first three times are not counted; (2) When the range of the test data of the main wavelength tested for 6 consecutive times is ≤15, stop the test, and record the main wavelength and relative spectrum test data of the last test as the effective test data of the main wavelength and relative spectrum of the test liquid this time; (3) When the range of the test data of the main wavelength tested for 5 consecutive times is ≤15, and the range of the test data of the 6th test is >15, the number of consecutive times is reduced by 1. The test is repeated for 4 times in a row, and so on. If the range of the test data for the Nth test is greater than 15, the number of consecutive tests is reduced by 1, until the range of the test data for the main wavelength is ≤15 for 6 consecutive times, then the test is stopped and the main wavelength and relative spectrum test data of the last test are recorded as the effective test data of the main wavelength and relative spectrum of the test liquid; (4) When the range of the test data for the main wavelength is ≤15 for 5 consecutive times, and the range of the test data for the Nth and N+1th tests is greater than 15, all test data are invalidated and the test is repeated according to the provisions of the above items (2) and (3).