Method for detecting content of hydrogen peroxide and application

Abstract

The invention provides a hydrogen peroxide content detection method and application. The method comprises the following steps: S1, mixing a to-be-detected sample containing hydrogen peroxide, quinoline boronic acid pinacol ester and a first solvent, and carrying out oxidation reaction to obtain a to-be-detected sample containing hydroxyquinoline; s2, preparing a series of hydroxyquinoline standard solutions with concentration gradients; detecting the standard solution by adopting a liquid chromatography to obtain the characteristic peak area Sn of the hydroxyquinoline in the standard solution; drawing a standard working curve by taking the concentration of the standard solution as an abscissa and Sn as an ordinate, and fitting to generate a linear regression equation; s3, detecting the to-be-detected sample by adopting liquid chromatography to obtain the characteristic peak area S0 of the hydroxyquinoline of the to-be-detected sample; and substituting the S0 into the linear regression equation to obtain the content of hydroxyquinoline in the to-be-tested sample, according to the stoichiometric ratio of the hydrogen peroxide in the to-be-detected sample to the hydroxyquinoline in the to-be-detected sample, the content of the hydrogen peroxide in the to-be-detected sample is calculated.

Description

Technical Field

[0001] This invention relates to the field of analytical testing technology, and more specifically, to a method and application for detecting hydrogen peroxide content in industrial wastewater. Background Technology

[0002] Hydrogen peroxide (H2O2), as an important oxidant and bioactive molecule, has wide applications in industrial catalysis, environmental remediation, food sterilization, and biomedicine. The accurate determination of its content is directly related to process control efficiency, product quality assessment, and biological metabolism research. Traditional hydrogen peroxide detection methods, such as iodometric titration and spectrophotometry, rely on monitoring the quantitative redox reaction between hydrogen peroxide and a specific indicator reagent to determine its concentration. This reaction causes a significant color change in the solution, and the endpoint is usually determined by visually observing this color change. Therefore, the accuracy and reliability of these methods largely depend on the operator's observation skills and experience. In environments containing various interfering substances, such as industrial wastewater and biological samples, the competitive reactions of coexisting elements and optical interference significantly reduce the sensitivity and selectivity of traditional methods, especially in the detection of trace amounts (concentrations below 100 mg / L) of hydrogen peroxide.

[0003] In recent years, patent and literature reports on hydrogen peroxide determination techniques have focused on derivatization strategies combined with instrumentation to improve selectivity and accuracy. For example, the recommended national standard GB / T 32112-2015, "Determination of Peroxides in Oral Care Products - High Performance Liquid Chromatography," proposes a method using triphenylphosphine (TPP) as a derivatization reagent. Hydrogen peroxide can oxidize triphenylphosphine to triphenylphosphine oxide (TPPO), which is then quantitatively analyzed by high performance liquid chromatography (HPLC), thereby achieving precise quantification of H2O2 content. This method effectively avoids interference from other matrices and improves test selectivity. However, commercially available TPP reagents generally contain trace amounts of TPPO impurities, and TPP is easily oxidized to TPPO when exposed to air, leading to background signal interference and thus deviations in detection results. This makes it difficult to meet the requirements for accurate detection of trace amounts of H2O2 in trace samples. Furthermore, industrial wastewater often contains other peroxides or redox compounds, which may also react with TPP to generate TPPO, affecting the accuracy and reliability of the detection.

[0004] In addition, commonly used detection methods include electrochemical methods and catalase indirect assays. However, although electrochemical methods are highly sensitive, they are easily affected by electrode surface contamination, leading to unstable detection results. Catalase indirect assays are limited by enzyme activity and stability, making it difficult to ensure continuous and accurate detection over long periods or in complex environments.

[0005] Therefore, developing and researching a detection method for hydrogen peroxide content that combines high sensitivity and strong anti-interference is of great significance for improving the selectivity and accuracy of trace hydrogen peroxide content detection, especially for samples with complex components (such as industrial wastewater or biological samples). Summary of the Invention

[0006] The main objective of this invention is to provide a method and application for detecting hydrogen peroxide content, in order to solve the problems of poor sensitivity and poor anti-interference ability in existing methods for detecting hydrogen peroxide content, and the resulting poor accuracy of detection results.

[0007] To achieve the above objectives, the present invention provides a method for detecting hydrogen peroxide content, comprising: step S1, mixing a test sample containing hydrogen peroxide, pinacol quinoline borate, and a first solvent, and subjecting the test sample and pinacol quinoline borate to an oxidation reaction in the first solvent to obtain a test sample containing hydroxyquinoline; the stoichiometric ratio of hydrogen peroxide in the test sample to hydroxyquinoline in the test sample is 1:1; step S2, mixing additionally introduced hydroxyquinoline with a second solvent to prepare a series of standard solutions with a concentration gradient; and detecting the standard solutions using liquid chromatography to obtain the characteristic peak area S of the additionally introduced hydroxyquinoline in the standard solutions. n Plot the concentration of the standard solution on the x-axis and the S-axis on the y-axis. n Plot a standard working curve with the vertical axis as the ordinate, fit the curve to generate a linear regression equation, and determine the coefficient of determination R of the linear regression equation. 2 ≥0.999; Step S3, use liquid chromatography to detect the test sample and obtain the characteristic peak area S0 of hydroxyquinoline in the test sample; substitute S0 into the linear regression equation obtained in step S2 to calculate the mass concentration of hydroxyquinoline in the test sample; calculate the content of hydrogen peroxide in the test sample based on the stoichiometric ratio of hydrogen peroxide in the test sample to hydroxyquinoline in the test sample.

[0008] Furthermore, the weight ratio of the sample to be tested to pinacol quinoline borate is (1-10):(0.05-0.5).

[0009] Furthermore, the weight ratio of pinacol quinoline borate to the volume ratio of the first solvent is (0.05–0.5) g: (5–20) mL.

[0010] Furthermore, the oxidation reaction is carried out at a temperature of 25–40°C for a time of 5–90 min, preferably 5–40 min.

[0011] Furthermore, the oxidation reaction is subjected to ultrasonic treatment or stirring.

[0012] Furthermore, the oxidation reaction is subjected to ultrasonic treatment at a temperature of 25–35°C for 5–20 min, with a power of 200–600 W and a frequency of 20–60 kHz; or, the oxidation reaction is subjected to stirring at a temperature of 25–30°C for 60–90 min, with a stirring rate of 400–700 rpm; or, the oxidation reaction is subjected to stirring at a temperature of 30–40°C for 30–60 min, with a stirring rate of 200–500 rpm.

[0013] Further, the pinacol quinoline borate is selected from 3-quinoline borate, 4-quinoline borate, 6-quinoline borate, or 8-quinoline borate; preferably, the pinacol quinoline borate is 3-quinoline borate.

[0014] Further, the first solvent is selected from one or more of the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile and chloroform; preferably, the first solvent is acetonitrile.

[0015] Further, the second solvent is selected from one or more of the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile and chloroform; preferably, the second solvent is the same as the first solvent.

[0016] Furthermore, in step S2, the mass concentration of the standard solution is 1–500 mg / L.

[0017] Furthermore, in step S2, at least 5 standard solutions with different mass concentrations are prepared, preferably 7 standard solutions with different mass concentrations.

[0018] To achieve the above objectives, another aspect of the present invention provides the application of the hydrogen peroxide content detection method provided in this application in detecting hydrogen peroxide content in industrial wastewater, biological samples, food, cosmetics, swimming pool water samples, or soil.

[0019] Applying the technical solution of this invention, this application provides a method for detecting hydrogen peroxide content. In step S1, the inventors innovatively use pinacol quinoline borate as a derivatizing reagent to react with hydrogen peroxide in the sample to be tested in a highly specific oxidation reaction, generating a single and stable oxidation product, hydroxyquinoline, according to the specific stoichiometric ratio described above. The above oxidation reaction produces no byproducts and maintains high specificity and selectivity even in complex matrix environments, effectively eliminating interference from other redox substances in the sample to be tested. It also reduces the subjectivity and inaccuracy caused by color interference in iodometric methods or matrix optical interference (such as turbidity or background absorption) in spectrophotometry, thus improving the accuracy and reliability of the detection results. Hydroxyquinoline exhibits excellent stability and good detection performance in subsequent liquid chromatography analysis, thereby improving detection sensitivity and ensuring the accuracy of detecting trace amounts (≤100 mg / L) of hydrogen peroxide. In step S2, a series of standard solutions with concentration gradients are prepared, and the characteristic peak area S of hydroxyquinoline in each standard solution is determined by liquid chromatography. n This allows for the establishment of a standard working curve, which can then be fitted to generate a linear regression equation. The detection method described in this application uses the coefficient of determination R of the linear regression equation... 2 Within the aforementioned range, the accuracy of the detection results can be ensured, providing a reliable calibration basis for the subsequent quantitative analysis of hydrogen peroxide content in the sample to be tested. In step S3, by substituting the characteristic peak area S0 of hydroxyquinoline in the test sample into the linear regression equation established in step S2, the concentration of hydroxyquinoline can be directly calculated. Then, based on the stoichiometric relationship, the hydrogen peroxide content in the test sample can be calculated, thereby ensuring the accuracy of the detection results.

[0020] In summary, the hydrogen peroxide content detection method provided in this application has excellent selectivity and high sensitivity, and can achieve accurate determination at trace levels of hydrogen peroxide concentration below 100 mg / L, effectively meeting the stringent requirements for hydrogen peroxide content analysis in scenarios such as industrial wastewater treatment, food testing, and biomedical research. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 The HPLC spectrum of 3-hydroxyquinoline in Example 13 of this application is shown. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0024] As described in the background section, existing methods for detecting hydrogen peroxide content suffer from poor sensitivity and poor anti-interference capabilities, resulting in poor accuracy of the detection results. To address these technical problems, this application provides a method for detecting hydrogen peroxide content, comprising: step S1, mixing a sample to be tested containing hydrogen peroxide, pinacol quinoline borate, and a first solvent, allowing the sample to be tested and pinacol quinoline borate to undergo an oxidation reaction in the first solvent to obtain a test sample containing hydroxyquinoline; the stoichiometric ratio of hydrogen peroxide in the sample to hydroxyquinoline in the test sample is 1:1; step S2, mixing additionally introduced hydroxyquinoline with a second solvent to prepare a series of standard solutions with a concentration gradient; and detecting the standard solutions using liquid chromatography to obtain the characteristic peak area S of the additionally introduced hydroxyquinoline in the standard solutions. n Plot the concentration of the standard solution on the x-axis and the S-axis on the y-axis. n Plot a standard working curve with the vertical axis as the ordinate, fit the curve to generate a linear regression equation, and determine the coefficient of determination R of the linear regression equation. 2 ≥0.999; Step S3, use liquid chromatography to detect the test sample and obtain the characteristic peak area S0 of hydroxyquinoline in the test sample; substitute S0 into the linear regression equation obtained in step S2 to calculate the mass concentration of hydroxyquinoline in the test sample; calculate the content of hydrogen peroxide in the test sample based on the stoichiometric ratio of hydrogen peroxide in the test sample to hydroxyquinoline in the test sample.

[0025] This application provides a method for detecting hydrogen peroxide content. In step S1, the inventors innovatively use pinacol quinoline borate as a derivatizing reagent to react with hydrogen peroxide in the sample to be tested, resulting in a highly specific oxidation reaction and generating a single, stable oxidation product—hydroxyquinoline—according to the specific stoichiometric ratio described above. This oxidation reaction produces no byproducts and maintains high specificity and selectivity even in complex matrix environments, effectively eliminating interference from other redox substances in the sample. It also reduces the subjectivity and inaccuracy issues caused by color interference in iodometric methods or matrix optical interference (such as turbidity or background absorption) in spectrophotometry, thus improving the accuracy and reliability of the detection results. Hydroxyquinoline exhibits excellent stability and good detection performance in subsequent liquid chromatography analysis, thereby improving detection sensitivity and ensuring the accuracy of detecting trace amounts (≤100 mg / L) of hydrogen peroxide. In step S2, a series of standard solutions with concentration gradients are prepared, and the characteristic peak area S of hydroxyquinoline in each standard solution is determined by liquid chromatography.n This allows for the establishment of a standard working curve, which can then be fitted to generate a linear regression equation. The detection method described in this application uses the coefficient of determination R of the linear regression equation... 2 Within the aforementioned range, the accuracy of the detection results can be ensured, providing a reliable calibration basis for the subsequent quantitative analysis of hydrogen peroxide content in the sample to be tested. In step S3, by substituting the characteristic peak area S0 of hydroxyquinoline in the test sample into the linear regression equation established in step S2, the concentration of hydroxyquinoline can be directly calculated. Then, based on the stoichiometric relationship, the hydrogen peroxide content in the test sample can be calculated, thereby ensuring the accuracy of the detection results.

[0026] In summary, the hydrogen peroxide content detection method provided in this application has excellent selectivity and high sensitivity, and can achieve accurate determination at trace levels of hydrogen peroxide concentration below 100 mg / L, effectively meeting the stringent requirements for hydrogen peroxide content analysis in scenarios such as industrial wastewater treatment, food testing, and biomedical research.

[0027] In a preferred embodiment, the weight ratio of the sample to be tested to pinacol quinoline borate is (1-10):(0.05-0.5). This weight ratio includes, but is not limited to, the range described above. Limiting it to this range helps ensure that the H2O2 in the sample can completely react with the pinacol quinoline borate, converting H2O2 completely into hydroxyquinoline. It also helps suppress side reactions, thereby improving the accuracy of the detection results.

[0028] In a preferred embodiment, the weight ratio of pinacol quinoline borate to the volume ratio of the first solvent is (0.05–0.5) g:(5–20) mL. This weight ratio of pinacol quinoline borate to the volume ratio of the first solvent includes, but is not limited to, the range described above. Limiting it to this range improves the dispersibility of pinacol quinoline borate, maintaining its concentration within a more suitable range. This, in turn, improves the efficiency of the oxidation reaction, promotes the complete conversion of H₂O₂ in the sample to be tested into hydroxyquinoline, and consequently improves the accuracy of the detection results.

[0029] In a preferred embodiment, the oxidation reaction temperature is 25–40°C, and the time is 5–90 min, preferably 5–40 min. The oxidation reaction temperature and time include, but are not limited to, the above ranges. Limiting them to these ranges is beneficial for improving the reaction efficiency and selectivity of the oxidation reaction, promoting the complete conversion of H2O2 in the sample to be tested into hydroxyquinoline, and also helps to suppress the occurrence of side reactions, thereby improving the accuracy of the detection results.

[0030] In a preferred embodiment, ultrasonic treatment or stirring is performed during the oxidation reaction. Ultrasonic treatment or stirring during the oxidation reaction improves the dispersion uniformity of the sample to be tested and pinacol quinoline borate, thereby increasing the reaction efficiency of the oxidation reaction and promoting the complete conversion of H2O2 in the sample to hydroxyquinoline, which in turn improves the accuracy and reliability of the detection results.

[0031] To further improve the dispersion uniformity of the sample to be tested and pinacol quinoline borate, further improve the reaction efficiency and selectivity of the oxidation reaction, and promote the complete conversion of H2O2 in the sample to hydroxyquinoline, thereby further improving the accuracy and reliability of the detection results, preferably, ultrasonic treatment is performed during the oxidation reaction, with the oxidation reaction temperature being 25-35℃, the time being 5-20 min, the ultrasonic treatment power being 200-600 W, and the frequency being 20-60 kHz; or, stirring is performed during the oxidation reaction, with the oxidation reaction temperature being 25-30℃, the time being 60-90 min, and the stirring rate being 400-700 rpm; or, stirring is performed during the oxidation reaction, with the oxidation reaction temperature being 30-40℃, the time being 30-60 min, and the stirring rate being 200-500 rpm.

[0032] In a preferred embodiment, the quinoline borate pinacol ester includes, but is not limited to, 3-quinoline borate pinacol ester, 4-quinoline borate pinacol ester, 6-quinoline borate pinacol ester, or 8-quinoline borate pinacol ester. Compared to other types, the above-mentioned quinoline borate pinacol esters exhibit higher reactivity and selectivity, which helps to suppress side reactions and thus promotes the conversion of H2O2 in the sample to be tested into a single and stable oxidation product, hydroxyquinoline, thereby improving the accuracy and reliability of subsequent detection results.

[0033] It should be noted that when the pinacol quinoline borate is 3-quinoline borate, 4-quinoline borate, 6-quinoline borate, or 8-quinoline borate, the oxidation products generated by its reaction with H2O2 in the sample to be tested are 3-hydroxyquinoline, 4-hydroxyquinoline, 6-hydroxyquinoline, or 8-hydroxyquinoline, respectively.

[0034] To further improve the accuracy and reliability of the detection results and enhance the detection sensitivity, quinoline borate pinacol ester is preferably 3-quinoline borate pinacol ester. Compared to quinoline borate pinacol esters with other substitution sites, 3-quinoline borate pinacol ester exhibits higher reactivity and selectivity, which helps suppress side reactions. This allows it to undergo a more specific oxidation reaction with H₂O₂ in the sample to generate a single and stable oxidation product, 3-hydroxyquinoline. Compared to other oxidation products, 3-hydroxyquinoline demonstrates superior stability and better detection performance in subsequent liquid chromatography analysis, thus improving detection sensitivity and accuracy in detecting trace amounts of hydrogen peroxide.

[0035] When pinacol quinoline borate is 3-quinoline borate, the chemical reaction equation for its oxidation reaction with H2O2 in the sample to be tested is as follows:

[0036]

[0037] In a preferred embodiment, the first solvent includes, but is not limited to, one or more of the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, and chloroform. The type of the first solvent includes, but is not limited to, the above-mentioned range. Limiting it to this range is beneficial for improving the dispersion uniformity of the sample to be tested and pinacol quinoline borate, for improving the reaction efficiency of the oxidation reaction, and for suppressing the occurrence of side reactions. Furthermore, the above-mentioned types of first solvents have good compatibility with the mobile phase in liquid chromatography and will not interfere with the detection of the target compound hydroxyquinoline, thereby improving the sensitivity and accuracy of the detection results.

[0038] To further improve the dispersion uniformity of the sample to be tested and pinacol quinoline borate, further improve the reaction efficiency of the oxidation reaction, further improve the compatibility of the first solvent with the mobile phase in liquid chromatography, and further improve the detection sensitivity and the accuracy of the detection results, preferably, the first solvent is acetonitrile.

[0039] In a preferred embodiment, the second solvent includes, but is not limited to, one or more of the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, and chloroform. The types of the second solvent include, but are not limited to, the range described above. Limiting it to this range is beneficial for improving the dispersibility of the additionally introduced hydroxyquinoline, and for improving the homogeneity and stability of the standard solution. Furthermore, the aforementioned types of second solvents have good compatibility with the mobile phase in liquid chromatography, which is beneficial for improving the accuracy of liquid chromatography in detecting the additionally introduced hydroxyquinoline in the standard solution. This leads to obtaining more accurate and reliable standard working curves and linear regression equations, providing a more reliable calibration basis for subsequent quantitative analysis of hydrogen peroxide content in the sample to be tested.

[0040] To improve the consistency and accuracy of the test results, preferably, the second solvent is the same as the first solvent.

[0041] In a preferred embodiment, in step S2, the mass concentration of the standard solution is 1–500 mg / L. The mass concentration of the standard solution includes, but is not limited to, the above range. Limiting it to this range helps to construct a linear working interval covering concentrations from trace amounts to higher levels, thereby improving the sensitivity and accuracy of quantitative analysis of trace H2O2 (detection limit as low as 5 mg / L).

[0042] In order to obtain more accurate and reliable standard working curves and linear regression equations, thereby improving the accuracy of detection results, in a preferred embodiment, at least five standard solutions with different mass concentrations are prepared in step S2.

[0043] To obtain more accurate and reliable standard working curves and linear regression equations, thereby further improving the accuracy of the detection results, preferably, seven standard solutions with different mass concentrations are prepared in step S2. Specifically, the mass concentrations of the standard solutions can be 2 mg / L, 5 mg / L, 10 mg / L, 50 mg / L, 100 mg / L, 250 mg / L, and 500 mg / L.

[0044] The second aspect of this application also provides an application of the hydrogen peroxide content detection method described above in this application for detecting hydrogen peroxide content in industrial wastewater, biological samples, food, cosmetics, swimming pool water samples, or soil. The hydrogen peroxide content detection method provided above in this application has excellent selectivity and high sensitivity, enabling accurate determination at trace levels of hydrogen peroxide concentration below 100 mg / L, effectively meeting the stringent requirements for hydrogen peroxide content analysis in scenarios such as industrial wastewater treatment, food testing, and biomedical research.

[0045] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0046] (I) Screening experiment for pinacol ester of quinoline borate

[0047] Examples 1 to 5

[0048] (1) Prepare a 30 wt% H2O2 solution, dilute it with acetonitrile to obtain a 15 wt% H2O2 solution for later use;

[0049] (2) Take four clean 250mL iodine flasks and transfer 2.0000g (all weighings below are accurate to 0.0001g) of the 15wt% H2O2 solution obtained in step (1) into each flask. Then, add 6mmol of the same mass of 3-quinoline borate pinacol ester, 4-quinoline borate pinacol ester, 6-quinoline borate pinacol ester and 8-quinoline borate pinacol ester to each of the four iodine flasks containing H2O2 solution. Then, add 10mL of acetonitrile to each iodine flask. After sealing, carry out the oxidation reaction under ultrasonic treatment at 25℃, 300W power and 40kHz frequency. Take samples at 10min and 20min after the start of the reaction and determine the molar amount of residual H2O2 in the samples by iodometric titration. The test results are shown in Table 1.

[0050] (3) Blank control group: Take a clean 250mL iodine flask, transfer 2.0000g of the 15wt% H2O2 solution obtained in step (1) into it, without introducing quinoline borate pinacol ester, replace quinoline borate pinacol ester with an equal amount of acetonitrile, then add 10mL of acetonitrile to the iodine flask, seal it, and perform ultrasonic treatment at 25℃ (power of 300W, frequency of 40kHz). Samples are taken at 10min and 20min after the start of ultrasonic treatment, and the molar amount of residual H2O2 in the sample is determined by iodometric titration. The test results are shown in Table 1.

[0051] Table 1

[0052]

[0053] As shown in Table 1, the reaction rates of pinacol esters with different substitution sites and H2O2 are different. After 20 min of reaction, the samples in Examples 3 and 4 still had a high amount of H2O2 residue, indicating that less H2O2 was consumed in the oxidation reaction, reflecting the low reactivity of 6-quinoline borate pinacol ester and 8-quinoline borate pinacol ester. The samples in Examples 1 and 2 had a lower amount of H2O2 residue after 20 min of reaction, and their reaction rates were slightly higher than those in Examples 3 and 4. However, compared with these examples, the 3-quinoline borate pinacol ester in Example 1 has the advantages of low electron density and small steric hindrance, and can quickly generate 3-hydroxyquinoline, with the fastest reaction rate. Therefore, the 3-quinoline borate pinacol ester in Example 1 showed better reactivity under the same conditions and was used as a derivatization reagent in subsequent experiments.

[0054] (II) First Solvent Screening Experiment

[0055] Examples 6 to 9

[0056] (1) Prepare a 30 wt% H2O2 solution, dilute it with acetonitrile to obtain a 15 wt% H2O2 solution for later use;

[0057] (2) Take four clean 250mL iodine flasks and transfer 2.0000g of the 15wt% H2O2 solution obtained in step (1) into each flask. Then, add 6mmol of 3-quinoline borate pinacol ester to each of the four iodine flasks containing H2O2 solution. Then, add 10mL of acetonitrile, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and chloroform (CHCl3) to each iodine flask. After sealing, carry out the oxidation reaction under ultrasonic treatment at 25℃, 300W power and 40kHz frequency. Take samples at 10min and 20min after the start of the reaction and determine the molar amount of residual H2O2 in the sample by iodometric titration. The test results are shown in Table 2.

[0058] Table 2

[0059]

[0060] As shown in Table 2, the reaction rate of 3-quinoline borate pinacol ester with H2O2 varies significantly in different first solvents. Samples in Examples 7 and 9 still showed high levels of H2O2 residue after 20 minutes of reaction, indicating that the oxidation reaction rate was low when using DMF and chloroform as solvents. Example 8, using DMSO as the solvent, showed a better reaction rate than Examples 7 and 9. This is because DMSO is a strongly polar aprotic solvent, which stabilizes intermediates and thus increases the oxidation reaction rate. However, DMSO has a sulfoxide structure, posing a risk of oxidation with H2O2 to form dimethyl sulfone, potentially leading to deviations in H2O2 consumption. Example 6, using acetonitrile as the solvent, showed the fastest oxidation reaction rate. This is because acetonitrile is a polar aprotic solvent, which favors the formation of the transition state. Furthermore, acetonitrile has low viscosity, stable chemical properties, and no side reactions. Therefore, acetonitrile was chosen as the solvent for subsequent experiments.

[0061] (III) Screening Experiment for Oxidation Reaction Conditions

[0062] Examples 10 to 12

[0063] (1) Prepare a 30 wt% H2O2 solution, dilute it with acetonitrile to obtain a 15 wt% H2O2 solution for later use;

[0064] (2) Take three clean 250mL iodine flasks and transfer 2.0000g of the 15wt% H2O2 solution obtained in step (1) into each flask. Then add 6mmol of 3-quinoline borate pinacol ester to each of the three iodine flasks containing H2O2 solution. Then add 10mL of acetonitrile to each iodine flask and seal them. Then carry out the oxidation reaction under different conditions (the specific reaction conditions are shown in Table 3). Take samples at 10min and 20min after the start of the reaction and determine the molar amount of residual H2O2 in the samples by iodometric titration. The test results are shown in Table 3.

[0065] Table 3

[0066]

[0067] As shown in Table 3, the oxidation reaction conditions have the following effects on reaction kinetics: In Example 10, only mechanical diffusion was relied upon, resulting in the lowest reaction rate (the residual amount of H2O2 after 20 min was 6.96 mmol); In Example 12, heating was performed, which increased the molecular kinetic energy and accelerated the oxidation reaction rate (the residual amount of H2O2 after 20 min was 4.87 mmol); In Example 11, ultrasonic treatment was used. The cavitation bubbles induced by ultrasound release extremely high local pressure and temperature upon collapse. This drastic physical change can lower the activation energy of the chemical reaction, and the locally increased temperature also increases the activity of the reacting molecules. Therefore, the oxidation reaction rate was the fastest (the residual amount of H2O2 decreased to 4.52 mmol after 10 min, and the reaction was complete after 20 min). Ultrasonic treatment can complete 100% of the above reactions within 20 min, and its reaction efficiency is significantly better than other reaction conditions. Therefore, ultrasonic treatment at 25℃, 300W power, and 40kHz frequency was used as the oxidation reaction conditions for subsequent experiments.

[0068] (iv) Validation of the detection method for hydrogen peroxide content

[0069] Examples 13 to 22

[0070] (1) Preparation of 3-hydroxyquinoline standard solution: Weigh 0.5000g of 3-hydroxyquinoline standard (purity ≥99.5%), place it in a 500mL volumetric flask, dissolve it in acetonitrile and dilute to volume to obtain a standard stock solution with a mass concentration of 1000mg / L; dilute the standard stock solution obtained by gradient dilution to prepare 3-hydroxyquinoline standard solutions with mass concentrations of 2mg / L, 5mg / L, 10mg / L, 50mg / L, 100mg / L, 250mg / L and 500mg / L respectively;

[0071] (2) Preparation of H2O2 standard solution: Weigh 3.4000g of H2O2 solution with a mass fraction of 30wt%, and make up to 1000mL with ultrapure water to obtain H2O2 standard stock solution with a mass concentration of 1000mg / L; dilute the H2O2 standard stock solution obtained by gradient dilution to prepare H2O2 standard solutions with mass concentrations of 2mg / L, 5mg / L, 10mg / L, 50mg / L, 100mg / L, 250mg / L, 500mg / L and 1000mg / L respectively;

[0072] (3) Transfer 5 mL of H2O2 standard solutions with mass concentrations of 10 mg / L, 50 mg / L, 100 mg / L, 500 mg / L and 1000 mg / L obtained in step (2) to 10 50 mL glass volumetric flasks respectively (wherein, each mass concentration of H2O2 standard solution is transferred to 2 different volumetric flasks respectively), and then add 0.1 g of 3-quinoline borate pinacol ester and 10 mL of acetonitrile to each volumetric flask. The oxidation reaction is carried out under ultrasonic treatment at 25 °C, 300 W power and 40 kHz frequency for 30 min. After the reaction is completed, the volume is adjusted with acetonitrile to obtain the test sample.

[0073] (4) A series of 3-hydroxyquinoline standard solutions with concentration gradients obtained in step (1) were detected by high performance liquid chromatography (HPLC, Agilent, 1260 Infinity II). The characteristic peak areas S1, S2, S3, S4, S5, S6 and S7 of 3-hydroxyquinoline in each 3-hydroxyquinoline standard solution were obtained. A standard working curve was plotted with the concentration of the 3-hydroxyquinoline standard solution as the abscissa and the characteristic peak area of ​​3-hydroxyquinoline as the ordinate. A linear regression equation was generated by fitting the curve using linear regression analysis. The determination coefficient R of the linear regression equation was determined. 2 ≥0.999;

[0074] The conditions for high performance liquid chromatography (HPLC) detection were as follows: column: C18 column (3.0 μm, 4.6 mm × 100 mm); mobile phase: acetonitrile-water gradient elution, the gradient elution program is shown in Table 4; flow rate: 0.6 mL / min; column temperature: 40 ℃; injection volume: 5 μL; detection wavelength: 331 nm.

[0075] Table 4

[0076]

[0077] (5) After filtering each test sample obtained in step (3) through an organic filter membrane with a pore size of 0.22 μm, high performance liquid chromatography (HPLC) was performed. The HPLC detection conditions were the same as in step (4). The characteristic peak area S0 of 3-hydroxyquinoline in each test sample was obtained. S0 was substituted into the linear regression equation obtained in step (4) to calculate the mass concentration of 3-hydroxyquinoline in the test sample. The content of H2O2 was calculated based on the stoichiometric ratio of hydrogen peroxide to 3-hydroxyquinoline of 1:1. The detection results are shown in Table 5.

[0078] The HPLC chromatogram of 3-hydroxyquinoline in Example 13 is as follows: Figure 1 As shown.

[0079] Table 5

[0080]

[0081] The limit of detection (LOD) was 1.5 mg / L (S / N = 3), and the limit of quantitation (LOQ) was 5 mg / L (S / N = 10). The relative errors of the detection results were all < ±6%, indicating that the above-mentioned method for detecting hydrogen peroxide content is highly accurate.

[0082] It should be noted that S / N is the signal-to-noise ratio, which is the ratio of the peak height of the target chromatographic peak to the peak value of the nearby baseline noise peak (i.e., the vertical distance between the highest and lowest points). It is used to measure the significance of the signal relative to the background noise.

[0083] Examples 23 to 28

[0084] The same batch of H2O2 standard solution (theoretical concentration of 114 mg / L, same as in Examples 17 and 18) was subjected to 6 parallel tests (the detection method is the same as in Examples 17 and 18) to verify the repeatability of the above-mentioned hydrogen peroxide content detection method; the detection results are shown in Table 6.

[0085] Table 6

[0086]

[0087] As can be seen from Table 6, the above-mentioned method for detecting hydrogen peroxide content has excellent repeatability.

[0088] Examples 29 to 37

[0089] The accuracy of the above-mentioned method for detecting hydrogen peroxide content was evaluated by spiked recovery experiments. Different masses (see Table 7 for details) of H2O2 standard (concentration of 1058 mg / L) were added to an H2O2 acetonitrile solution with a known H2O2 concentration of 487 mg / L to obtain test samples. The H2O2 content in the test samples was detected (the detection method is the same as in Examples 13 to 22), and the detection results are shown in Table 7.

[0090] The recovery rate is calculated according to formula (I). Where c2 is the detection concentration of H2O2 in the test sample, m2 is the mass of the test sample (i.e., the sum of the masses of the H2O2 acetonitrile solution and the H2O2 standard), c1 is the concentration of H2O2 in the H2O2 acetonitrile solution (i.e., 487 mg / L), m1 is the mass of the H2O2 acetonitrile solution, c0 is the concentration of H2O2 in the H2O2 standard (i.e., 1058 mg / L), and m0 is the mass of the H2O2 standard.

[0091] Table 7

[0092]

[0093] As can be seen from Table 7, the recovery rate is between 97.7% and 103.6%, and the relative standard deviation (RSD) is 1.97%. Therefore, the detection method provided in this application has high accuracy.

[0094] Comparative Examples 1 to 4

[0095] The iodometric determination of H2O2 content includes the following steps:

[0096] (1) Weigh 5.0000g of H2O2 samples of different concentrations (the samples are the same as those in Examples 15, 16, 19 and 20 respectively), place them in an iodine flask, add 10mL of 10wt% H2SO4 solution and 2.0g of KI in sequence, make up to 50mL with ultrapure water, let stand in the dark for 30 minutes, and then add 10mL of ultrapure water along the wall of the flask to rinse away any volatile iodine.

[0097] (2) Titration analysis: Titrate with 0.1000mol / L Na2S2O3 standard solution until the solution turns light yellow; add 1mL starch indicator and continue titrating until the blue color disappears and does not return within 30 seconds, and record the volume of Na2S2O3 consumed; at the same time, perform a blank experiment;

[0098] (3) Calculate the H2O2 content: Calculate the H2O2 content based on the titration volume difference and the stoichiometric relationship of the reaction (H2O2:I2:Na2S2O3=1:1:2).

[0099] The test results are shown in Table 8.

[0100] Table 8

[0101]

[0102] As shown in Table 8, the detection method for hydrogen peroxide content provided in this application and the iodometric method have relatively small errors when detecting the test sample with an H2O2 mass concentration of 487 mg / L. However, when detecting the test sample with an H2O2 mass concentration of 54 mg / L, the precision of the iodometric method decreases significantly. The relative standard deviation (RSD) of Comparative Examples 1 to 4 is 5.66%, while the RSD of Examples 15, 16, 19 and 20 is 0.90%, which is significantly better than the comparative examples. This indicates that the detection method for hydrogen peroxide content provided in this application can achieve accurate determination at trace levels with H2O2 concentrations below 100 mg / L.

[0103] The sources of error in the iodometric titration were analyzed, and the results are as follows: (1) Iodine is easily decomposed by light, oxygen and temperature, which leads to the premature titration endpoint; (2) Dark or turbid samples will mask the color reaction of starch-I2 complex, causing misjudgment of the endpoint; (3) Judging the endpoint of the reaction by observing the color change with the naked eye is prone to subjective error.

[0104] Comparative ratios 5 to 8

[0105] The determination of H2O2 content using triphenylphosphine as a derivatization reagent includes the following steps:

[0106] (1) Preparation of H2O2 standard solution: Weigh 3.4000g of H2O2 solution with a mass fraction of 30wt%, and make up to 1000mL with ultrapure water to obtain H2O2 standard stock solution with a mass concentration of 1000mg / L; dilute the H2O2 standard stock solution obtained by gradient dilution to prepare H2O2 standard solutions with mass concentrations of 5mg / L, 10mg / L, 50mg / L, 100mg / L, 200mg / L and 300mg / L and 1000mg / L respectively;

[0107] (2) Preparation of internal standard solution: Weigh 0.5000g of diethyl phthalate (DEP) and add it to a 500mL volumetric flask. Dilute to volume with acetonitrile to obtain a DEP internal standard stock solution with a mass concentration of 1000mg / L.

[0108] (3) Transfer 1 mL of H2O2 standard solution with a mass concentration of 10 mg / L and 100 mg / L obtained in step (1) to four 10 mL brown volumetric flasks respectively (wherein, each mass concentration of H2O2 standard solution is transferred to two different volumetric flasks respectively). Then add 1 mL of triphenylphosphine solution and 4 mL of DEP internal standard stock solution obtained in step (2) to each volumetric flask. After making up to volume with acetonitrile, react at 25 °C in the dark for 30 min to obtain the sample to be tested.

[0109] (4) After filtering each sample obtained in step (3) through an organic filter membrane with a pore size of 0.22 μm, perform HPLC detection. Plot a standard curve with the ratio of the characteristic peak area of ​​the oxidation product triphenylphosphine oxide (TPPO) to the internal standard DEP as the ordinate and the H2O2 concentration as the abscissa. Fit a linear regression equation according to the linear regression analysis method. Calculate the H2O2 content based on the sample peak area ratio and the regression equation.

[0110] The HPLC detection conditions were as follows: column: C18 column (5.0 μm, 4.6 mm × 250 mm); mobile phase: acetonitrile-water gradient elution, the gradient elution program is shown in Table 9; flow rate: 1 mL / min; column temperature: 35 ℃; injection volume: 10 μL; detection wavelength: 225 nm.

[0111] Table 9

[0112]

[0113] The test results are shown in Table 10.

[0114] Table 10

[0115]

[0116] As shown in Table 10, when triphenylphosphine was used as the derivatization reagent, the average detection result of Comparative Examples 7 and 8 for the test samples with a mass concentration of 13 mg / L was 16.5 mg / L, with a relative error of +26.9%, which was significantly higher than the relative error (-7.7%) when 3-quinoline borate pinacol ester was used as the derivatization reagent (i.e., Examples 21 and 22). The average detection result of Comparative Examples 5 and 6 for the test samples with a mass concentration of 114 mg / L was 118 mg / L, with a relative error of +3.5%, while the relative error of the detection results of Examples 17 and 18 was only +0.4%, which was significantly better than the comparative examples.

[0117] The sources of error when triphenylphosphine is used as a derivatization reagent were analyzed, and the results are as follows: (1) Commercial triphenylphosphine (TPP) reagent contains trace amounts of triphenylphosphine oxide (TPPO) impurities, which leads to higher detection values ​​for low-concentration samples; (2) There are side reactions. TPP is easily oxidized to TPPO when exposed to air, which also interferes with the quantitative analysis results.

[0118] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0119] The method for detecting hydrogen peroxide content provided in this application innovatively selects pinacol quinoline borate as a derivatizing reagent in step S1. This reagent reacts with hydrogen peroxide in the sample to undergo a highly specific oxidation reaction, generating a single and stable oxidation product, hydroxyquinoline, according to the specific stoichiometric ratio described above. This oxidation reaction produces no byproducts and maintains high specificity and selectivity even in complex matrix environments, effectively eliminating interference from other redox substances in the sample. It also reduces the subjectivity and inaccuracy issues caused by color interference in iodometric methods or matrix optical interference (such as turbidity or background absorption) in spectrophotometry, thus improving the accuracy and reliability of the detection results. Hydroxyquinoline exhibits excellent stability and good detection performance in subsequent liquid chromatography analysis, thereby improving detection sensitivity and ensuring the accuracy of trace hydrogen peroxide detection. In step S2, a series of standard solutions with concentration gradients are prepared, and the characteristic peak area S of hydroxyquinoline in each standard solution is determined by liquid chromatography. n This allows for the establishment of a standard working curve, which can then be fitted to generate a linear regression equation. The coefficient of determination R0 of the linear regression equation is then defined. 2 A value ≥0.999 ensures the accuracy of the detection results and provides a reliable calibration basis for the subsequent quantitative analysis of hydrogen peroxide content in the sample. In step S3, by substituting the characteristic peak area S0 of hydroxyquinoline in the test sample into the linear regression equation established in step S2, the concentration of hydroxyquinoline can be directly calculated. Then, based on the stoichiometric relationship, the hydrogen peroxide content in the sample can be calculated, thus ensuring the accuracy of the detection results.

[0120] In summary, the hydrogen peroxide content detection method provided in this application has excellent selectivity and high sensitivity, and can achieve accurate determination at trace levels of hydrogen peroxide concentration below 100 mg / L, effectively meeting the stringent requirements for hydrogen peroxide content analysis in scenarios such as industrial wastewater treatment, food testing, and biomedical research.

[0121] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the hydrogen peroxide content, characterized by, The detection method comprises: Step S1, mixing the sample to be detected containing hydrogen peroxide, quinolinic acid pinacol ester and a first solvent, so that the sample to be detected and the quinolinic acid pinacol ester perform an oxidation reaction in the first solvent to obtain a test sample containing hydroxyquinoline; the stoichiometric ratio of hydrogen peroxide in the sample to be detected to the hydroxyquinoline in the test sample is 1:1; Step S2, mixing the extra-introduced hydroxyquinoline with a second solvent to prepare a series of standard solutions with concentration gradient; detecting the standard solutions by liquid chromatography to obtain characteristic peak area S of the extra-introduced hydroxyquinoline in the standard solutions n ; taking the concentration of the standard solutions as the horizontal coordinate and taking S n as the vertical coordinate, drawing a standard working curve, fitting to generate a linear regression equation, and the determination coefficient R 2 of the linear regression equation is ≥0.999; Step S3, detecting the test sample by liquid chromatography to obtain the characteristic peak area S0 of the hydroxyquinoline in the test sample; substituting the S0 into the linear regression equation obtained in step S2 to calculate the mass concentration of the hydroxyquinoline in the test sample; and calculating the content of the hydrogen peroxide in the sample to be detected according to the stoichiometric ratio of the hydrogen peroxide in the sample to be detected to the hydroxyquinoline in the test sample.

2. The method for detecting hydrogen peroxide content according to claim 1, characterized in that, The weight ratio of the sample to be detected to the quinolinic acid pinacol ester is (1-10):(0.05-0.5).

3. The method for detecting the hydrogen peroxide content according to claim 1 or 2, characterized by, The ratio of the weight of the quinolinic acid pinacol ester to the volume of the first solvent is (0.05-0.5) g:(5-20) mL.

4. The method for detecting the hydrogen peroxide content according to any one of claims 1 to 3, characterized by, The temperature of the oxidation reaction is 25-40°C, and the time is 5-90 min, preferably 5-40 min. Preferably, ultrasonic treatment or stirring is performed during the oxidation reaction.

5. The method of claim 4, wherein the hydrogen peroxide content is determined by the method of claim 1. During the oxidation reaction, the ultrasonic treatment is performed, the temperature of the oxidation reaction is 25-35°C, the time is 5-20 min, the power of the ultrasonic treatment is 200-600 W, and the frequency is 20-60 kHz; or During the oxidation reaction, the stirring is performed, the temperature of the oxidation reaction is 25-30°C, the time is 60-90 min, and the stirring rate is 400-700 rpm; or During the oxidation reaction, the stirring is performed, the temperature of the oxidation reaction is 30-40°C, the time is 30-60 min, and the stirring rate is 200-500 rpm.

6. The method for detecting hydrogen peroxide content according to claim 1, characterized in that, The quinolinic acid pinacol ester is selected from 3-quinolinic acid pinacol ester, 4-quinolinic acid pinacol ester, 6-quinolinic acid pinacol ester or 8-quinolinic acid pinacol ester; Preferably, the quinolinic acid pinacol ester is 3-quinolinic acid pinacol ester.

7. The method for detecting hydrogen peroxide content according to claim 1, characterized in that, The first solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile and chloroform; Preferably, the first solvent is acetonitrile.

8. The method of claim 7, wherein the hydrogen peroxide content is determined by the method of claim 1. The second solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile and chloroform; Preferably, the second solvent is the same as the first solvent.

9. The method of detecting the hydrogen peroxide content according to any one of claims 1 to 8, characterized in that, In step S2, the mass concentration of the standard solution is 1-500 mg / L; Preferably, in step S2, at least 5 standard solutions with different mass concentrations are prepared, and more preferably 7 standard solutions with different mass concentrations are prepared.

10. Use of the method for detecting the hydrogen peroxide content according to any one of claims 1 to 9 for detecting the hydrogen peroxide content in industrial waste water, biological samples, food, cosmetics, swimming pool water samples or soil.

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