CN110887836A

CN110887836A - Method for detecting content of hydrogen peroxide

Info

Publication number: CN110887836A
Application number: CN201911279839.2A
Authority: CN
Inventors: 朱巍然; 杨小弟; 王坤; 郝楠; 李卉卉; 林军
Original assignee: Changzhou Institute Of Innovation And Development Nanjing Normal University
Current assignee: Changzhou Yanglin Environmental Protection Technology Co.,Ltd.
Priority date: 2019-12-13
Filing date: 2019-12-13
Publication date: 2020-03-17
Anticipated expiration: 2039-12-13
Also published as: CN110887836B

Abstract

The invention provides a method for detecting the content of hydrogen peroxide, which comprises the following steps: providing a carbon nitride colorimetric sensor doped with oxygen; mixing the oxygen-doped carbon nitride colorimetric sensor with a 3,3',5,5' -tetramethylbenzidine solution and a phosphate buffer solution, adding a sample to be detected containing hydrogen peroxide for reaction, and adding acid to terminate the reaction to obtain a reaction solution; the reaction liquid is centrifugally separated to obtain supernatant liquid for ultraviolet spectrum analysis, and the content of the hydrogen peroxide is calculated according to a standard curve.

Description

Method for detecting content of hydrogen peroxide

Technical Field

The invention relates to the field of colorimetric detection, in particular to a method for detecting the content of hydrogen peroxide.

Background

Colorimetric detection refers to a method of determining the content of a component to be measured by comparing or measuring the color depth of a solution of a colored substance. The principle is that based on the color of the solution of the substance to be measured or the color of the color solution produced after adding color developing agent, the color depth is in direct proportion to the substance content, and the content of the substance in the solution can be measured according to the intensity of the light absorbed by the color solution. The method has the advantages of low cost, simple equipment, simple and convenient operation and the like, and is widely applied to various target detection in daily life.

The hydrogen peroxide is a colorless liquid, has oxidation and reduction properties, is a strong oxidant and is easy to decompose. The strong oxidizing property of hydrogen peroxide can inhibit the growth of bacteria, and can be widely used in industry and medical field as a stabilizer or preservative. However, the use of the compound in the food field is strictly controlled, and in biochemical reaction, a large amount of hydroxyl free radicals can be generated, participate in electron transfer and hydroxylation reaction, cause cell necrosis or mutation, and have great harm to human bodies. Some illegal vendors add hydrogen peroxide in excess or illegally to food because of its high sterilization efficiency, oxidative bleaching action and easy decomposition, low residue, to kill microorganisms in food, packaging materials and equipment containers and to increase the color pleasure of food. In the food quality inspection reports conducted in China, it has been shown that excessive hydrogen peroxide remains in some processed legume products, flour products, meatballs, boiled salted ducks, boiled salted chickens and the like. Therefore, the research and application of the determination method for efficiently, sensitively and rapidly detecting the hydrogen peroxide in the food are established, and the method has important significance.

Disclosure of Invention

In view of the above drawbacks of the prior art, the present invention provides a method for detecting hydrogen peroxide content, which is used to solve the problems of slow hydrogen peroxide detection speed, high cost and low accuracy in the prior art.

In order to achieve the above objects and other related objects, the present invention provides a method for detecting hydrogen peroxide content, comprising the steps of: providing a carbon nitride colorimetric sensor doped with oxygen; mixing the oxygen-doped carbon nitride colorimetric sensor with a 3,3',5,5' -tetramethylbenzidine solution and a phosphate buffer solution, adding a sample to be detected containing hydrogen peroxide for reaction, and adding acid to stop the reaction to obtain a reaction solution; and centrifugally separating the reaction solution to obtain supernatant liquid, performing ultraviolet spectrum analysis, and calculating the content of the hydrogen peroxide according to a standard curve.

In one embodiment, the oxygen-doped carbon nitride colorimetric sensor is prepared by acid treatment after calcination of a nitrogen-carbon precursor, wherein the nitrogen-carbon precursor is any one of melamine and urea, the acid comprises nitric acid and sulfuric acid, and the volume ratio of the nitric acid to the sulfuric acid is (1:1) - (3: 1).

In one embodiment, the oxygen content of the oxygen-doped carbon nitride colorimetric sensor is 12-16%.

In one embodiment, the acid treatment time is 0.5 to 2 hours.

In one embodiment, the reaction time is 15 to 25 minutes.

In one embodiment, the reaction temperature is 30-40 ℃.

In one embodiment, the pH of the phosphate buffer is 3.0-4.0.

In one embodiment, the concentration of the 3,3',5,5' -tetramethylbenzidine solution is 6-10 mM.

In one embodiment, the standard curve relates R linearly to the concentration of hydrogen peroxide in the range of 100nM to 50uM²>0.99, wherein the detection limit of the hydrogen peroxide is 40-50 nM.

In an embodiment, the sample to be tested includes any one of bean product, flour product, meat ball, boiled salted chicken, boiled salted duck and milk.

As described above, the method for detecting hydrogen peroxide content provided by the invention has the following beneficial effects: the oxygen-doped carbon nitride constructed by the invention has activity similar to peroxidase, the oxygen-doped carbon nitride has electrocatalytic activity on hydrogen peroxide, the electron transfer process in the reaction can be accelerated, the ultrasensitive detection on the hydrogen peroxide is realized, the concentration of the hydrogen peroxide and the intensity of an ultraviolet absorption peak at 450nM show a good linear relation in a concentration range of 100 nM-50 MuM of the hydrogen peroxide, and the detection limit can reach 42 nM. Compared with the traditional detection method, the colorimetric detection method for hydrogen peroxide by using the oxygen-doped carbon nitride provided by the invention has the characteristics of simple and flexible operation, simple instrument and equipment, small reagent dosage, low detection cost and the like.

Drawings

FIG. 1 is a flow chart of the detection method of the present invention.

FIG. 2 shows scanning electron micrographs of the obtained carbon nitride (B) in inventive sample 1(A) and sample 1.

FIG. 3 is a graph showing the correlation between the detected concentration of hydrogen peroxide and the intensity of the ultraviolet absorption peak at 450nm in the reaction solution (in-line graph is a linear graph).

FIG. 4 shows the UV absorption spectra of sample 1 and sample 2 according to the present invention after catalytic reaction.

FIG. 5 shows the UV absorption spectra of

samples

1, 3 and 4 according to the present invention after catalytic reaction.

FIG. 6 shows the UV absorption spectra of sample 1 and samples 5-8 after catalytic reaction.

FIG. 7 is a graph showing a comparison of the UV absorption spectra of sample 1 for different catalytic reactions, wherein (a) sample 1 catalyzes the TMB autoxidation reaction; (b) catalyst-free TMB and H₂O₂Carrying out reaction; (c) TMB and H catalyzed by sample 1₂O₂Reaction (d) g-C obtained in sample 1₃N₄Catalyzed TMB and H₂O₂And (4) reacting.

FIG. 8 is a graph showing the UV absorption spectra of sample 1 under different catalytic reaction conditions, wherein: pH (A), reaction temperature (B), reaction time (C), TMB concentration (D).

FIG. 9 is a graph of the selectivity analysis of the hydrogen peroxide detection of sample 1.

Detailed Description

The present invention is further illustrated below with reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention.

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As shown in fig. 1 to 9, the invention provides a method for detecting hydrogen peroxide content, which is simple and flexible in operation, simple in instrument and equipment, less in reagent consumption and low in detection cost, and can be effectively applied to detection of hydrogen peroxide in food such as milk.

The detection method comprises the steps of S1-S3: s1: providing a carbon nitride colorimetric sensor doped with oxygen; s2: mixing the oxygen-doped carbon nitride colorimetric sensor with a 3,3',5,5' -tetramethylbenzidine solution and a phosphate buffer solution, adding a sample to be detected containing hydrogen peroxide for reaction, and adding acid to terminate the reaction to obtain a reaction solution; s3: and centrifugally separating the reaction solution to obtain supernatant liquid, performing ultraviolet spectrum analysis, and calculating the content of the hydrogen peroxide according to a standard curve.

As shown in fig. 1 to 2, in step S1, the oxygen-doped carbon nitride colorimetric sensor is prepared by acid treatment of a nitrogen-carbon precursor after calcination, the nitrogen-carbon precursor is any one of melamine and urea, the calcination temperature may be 500 to 600 ℃, the calcination may be performed in a muffle furnace, the temperature rise rate of the muffle furnace may be 3 to 5 ℃/min, the calcination time may be 4 to 5 hours, the calcination may be followed by natural cooling, the cooling may be to room temperature, the calcination may be followed by grinding, the grinding may be followed by repeating the calcination, the repeating number may be 1 to 2, and fine and uniform carbon nitride (g-C) may be obtained after the calcination₃N₄) And (3) powder. The acid treatment may be a treatment with a strong acid which, after the treatment, may result in the carbon nitride (g-C)₃N₄) And obtaining the oxygen-doped carbon nitride (OCN), wherein the acid can be a mixture of nitric acid and sulfuric acid, the volume ratio of the nitric acid to the sulfuric acid can be (1:1) - (3:1), and the acid treatment time can be 0.5-8 hours.

In one embodiment, the oxygen-doped carbon nitride colorimetric sensor can be prepared by the following steps: carefully grinding 8.0g of melamine in an agate mortar, adding the ground powder into a crucible, covering the crucible with a cover, placing the crucible in a muffle furnace, heating to 550 ℃ at the speed of 3 ℃/min, keeping the temperature at 550 ℃ for 4 hours, naturally cooling to room temperature, taking out the powder, placing the taken-out carbon nitride solid in the mortar, grinding the carbon nitride solid into powder, repeating the heating step again, and carrying out secondary calcination to obtain carbon nitride (g-C)₃N₄) And (3) powder. Adding 0.5g of carbon nitride powder subjected to secondary calcination into a 100mL three-necked flask, respectively adding 20mL of nitric acid and 20mL of sulfuric acid, strongly stirring at room temperature for 0.5 hour, taking out the solution in the flask, subpackaging the solution in a 5mL centrifuge tube, centrifuging at 12000 rpm for five minutes, removing residual acid liquor, and repeating the centrifuging step for five times by using deionized water to obtain a solid sample until the pH value of the solution is neutral to obtain a sample 1. As shown in FIG. 2, a scanning electron micrograph of sample 1 and g-C obtained in sample 1 without oxygen doping₃N₄By contrast, the oxygen-doped carbon nitride (OCN) treated by the acid has more uniform texture.

Sample 2 was prepared in a similar manner to sample 1, with the carbon-nitrogen precursor being urea.

Sample 3 was prepared similarly to sample 1, with the specific amounts of acid being 20mL of nitric acid and 10mL of sulfuric acid, i.e., the volume ratio of nitric acid to sulfuric acid was 2: 1. Sample 4 was prepared similarly to sample 1, with the specific amounts of acid being 30mL of nitric acid and 10mL of sulfuric acid, i.e., the volume ratio of nitric acid to sulfuric acid was 3: 1.

The preparation steps of samples 5 to 8 are similar to sample 1, and the acid treatment time is 2 hours, 4 hours, 6 hours and 8 hours in sequence.

In step S2, the sample to be tested may include any one of bean product, flour product, meat ball, boiled chicken, boiled salted duck, and milk, such as milk, and the milk may be pre-processed before being tested, and the pre-processing method may be: centrifuging the milk sample at 13000-15000 rpm for 20-40 minutes to remove organic substances such as protein, fat and the like in the milk, and further centrifuging the supernatant obtained by centrifugation at 13000-15000 rpm until no precipitation occurs, wherein the supernatant of the non-precipitated milk can be used as a sample to be detected for standby.

The reaction may comprise the steps of: mixing the oxygen-doped carbon nitride with 3,3',5,5' -tetramethylbenzidine solution (TMB) and Phosphate Buffer Solution (PBS), adding a sample to be detected containing hydrogen peroxide for reaction, adding acid to stop the reaction to obtain reaction liquid, centrifugally separating the reaction liquid to obtain supernatant for ultraviolet spectrum analysis, and calculating the content of hydrogen peroxide according to a standard curve. The reaction principle is mainly that the reaction of TMB and hydrogen peroxide is catalyzed by oxygen-doped carbon nitride.

The reaction time of the oxygen-doped carbon nitride can be suspension of oxygen-doped carbon nitride (OCN), the suspension can be obtained by mixing the oxygen-doped carbon nitride with water and then carrying out ultrasonic treatment, the ultrasonic treatment can enable the oxygen-doped carbon nitride to be in a flake structure, the surface area of the oxygen-doped carbon nitride is increased, the catalytic capacity is enhanced, and the concentration of the oxygen-doped carbon nitride suspension can be 1 mg/L. The 3,3',5,5' -tetramethylbenzidine solution (TMB) can be obtained by dissolving the 3,3',5,5' -tetramethylbenzidine solution (TMB) in dimethyl sulfoxide, the concentration of the 3,3',5,5' -tetramethylbenzidine solution (TMB) can be 2-14 mM, the phosphate buffer solution can play a role in adjusting the pH value in a reaction system, the pH of the phosphate buffer solution can be 2-7, and the concentration of the phosphate buffer solution can be 0.1M. The reaction temperature can be 20-70 ℃, and the reaction time can be 5-35 minutes.

As shown in fig. 3, in step S3, the method for creating the standard curve may include: the 20 μ LOCN suspension (1mg/L) obtained from sample 1 was pipetted, and 30 μ LTMB solution (8mM), 400 μ L PBS (0.1M, pH4.0) was added to a 2mL centrifuge tube and vortexed for 30s to mix the solutions well, followed by the addition of 50 μ L PBS solution (1, 10, 30, 50, 100, 150, 200, 250, 300, 500 μ M) containing different concentrations of hydrogen peroxide, and incubated for 15 minutes with shaking at 40 ℃ in a constant temperature water bath shaker. After the reaction was complete, 20. mu. L H was added₂SO₄(2M) the reaction was stopped and the color of the solution was changed from blueIs yellow. Finally, the tube was centrifuged at 13000 rpm for 10 minutes, and the supernatant was taken out and the intensity of the absorption peak at 450nm was recorded by an ultraviolet spectrophotometer. A standard curve of hydrogen peroxide is established by taking the concentration of hydrogen peroxide as an abscissa and the intensity of an absorption peak at 450nm as an ordinate. As can be seen from FIG. 6, the present invention has good linearity in the range of 100nM to 50uM, and the linear relationship R²Values may be greater than 0.99 and the limit of detection of hydrogen peroxide according to the standard curve may be 40-50 nM, for example 42 nM.

In one embodiment, a method for detecting the content of hydrogen peroxide in milk may include the following steps: the test milk sample was centrifuged at 14000 rpm for 30 minutes to remove organic substances such as protein and fat from the milk. The supernatant from the centrifugation was then further centrifuged at 14000 rpm until no pellet was obtained. mu.L of OCN suspension (1mg/L) obtained in

sample

1, and 30. mu.L of TMB solution (8mM), 400. mu.L of PBS (0.1M, pH4.0) solution were pipetted into a 2mL centrifuge tube, the solution was mixed well by vortexing for 30s, then 50. mu.L of the supernatant of the milk sample was added, and the mixed solution was incubated in a constant temperature water bath shaker at 40 ℃ for 15 minutes with shaking. After the reaction was complete, 20. mu. L H was added₂SO₄(2M) the reaction was stopped and the color of the solution changed from blue to yellow. And finally, centrifuging the centrifuge tube at 13000 r/min for 10 min, taking out supernatant, recording the absorption peak intensity at 450nm by using an ultraviolet spectrophotometer, and comparing with a standard curve to obtain the concentration of the hydrogen peroxide.

The following are made for samples 1 to 8 and carbon nitride (g-C) obtained in sample 1₃N₄) The catalytic performance of (2) was evaluated.

The evaluation can be determined by using the ultraviolet absorption peak intensity after the obtained oxygen-doped carbon nitride catalyzes the reaction of 3,3',5,5' -Tetramethylbenzidine (TMB) and hydrogen peroxide in Phosphate Buffered Saline (PBS).

As shown in FIGS. 4 to 5, 20. mu.L of OCN suspension obtained from samples 1 to 4 and having a concentration of 1mg/L was mixed with 30. mu.L of TMB solution having a concentration of 4mM, 400. mu.L of PBS having a concentration of 0.1M and a pH of 4 in a 2mL centrifuge tube,vortex for 30s to mix well and then add 50 μ LH₂O₂(500. mu.M) after that, the centrifuge tube is placed in a constant temperature water bath shaker for shaking incubation at 40 ℃ for 30 minutes, and then 20. mu. L H is added₂SO₄(2M) the reaction was stopped and the color of the solution changed from blue to yellow. Finally, the tube was centrifuged at 13000 rpm for 10 minutes, and the supernatant was taken out and the intensity of the absorption peak at 450nm was recorded by an ultraviolet spectrophotometer.

As shown in FIGS. 6 to 7,

samples

1, 5 to 8, and carbon nitride (g-C) in sample 1 were measured₃N₄) 20 μ L of OCN suspension or g-C obtained at a concentration of 1mg/L₃N₄The suspension was mixed with 30. mu.L of 8mM TMB solution, 400. mu.L of 0.1M pH4 PBS, added to a 2mL centrifuge tube, vortexed for 30 seconds to mix the solution thoroughly, and 50. mu.L of LH was added₂O₂(500. mu.M) after the incubation, the centrifuge tube was placed in a constant temperature water bath shaker at 40 ℃ and incubated for 30 minutes with shaking, 20. mu. L H was added₂SO₄(2M) the reaction was stopped and the color of the solution changed from blue to yellow. Finally, the tube was centrifuged at 13000 rpm for 10 minutes, the supernatant was removed and the absorbance peak intensity at 450nm was recorded using an ultraviolet spectrophotometer.

As can be seen from fig. 4 to 6, when melamine is used as a nitrogen-carbon precursor, the catalytic activity of the oxygen-doped carbon nitride prepared by the method is higher than that of the oxygen-doped carbon nitride prepared by urea, and when the volume ratio of the nitric acid to the sulfuric acid is 1:1, the catalytic activity of the oxygen-doped carbon nitride prepared by the method is higher. The oxygen-doped carbon nitride shown in sample 1, which had an acid treatment time of 0.5 hours, exhibited the highest uv absorption peak intensity and high catalytic activity. g-C prepared from sample 1, samples 5-8 and sample 1₃N₄As shown in Table 1, it can be seen that the oxygen content of the OCN may be 12-16%, for example 12.89%.

TABLE 1

As shown in FIG. 7, the test method of FIG. 7 is similar to that of FIG. 5, and in FIG. 7 (a) only TMB and OCN suspension obtained from sample 1 were addedMeasuring the ultraviolet absorption peak intensity after the reaction of the floating liquid, and measuring TMB and H in the step (b) without adding any catalyst₂O₂Ultraviolet absorption peak intensity after reaction, (C) ultraviolet absorption peak intensity after catalysis of TMB and hydrogen peroxide reaction by OCN suspension obtained from sample 1, and (d) g-C obtained from sample 1₃N₄The ultraviolet absorption peak intensity after the reaction of the TMB and the hydrogen peroxide is catalyzed can be seen, the catalytic performance of the carbon nitride after the oxygen doping is obviously superior to that of the carbon nitride without doping, and the TMB can also undergo autooxidation when the hydrogen peroxide is not added for reaction, which shows that the oxygen-doped carbon nitride has higher activity.

As shown in FIG. 8, the OCN obtained in sample 1 was evaluated for catalytic performance under different reaction conditions. The ordinate in fig. 8 is a relative absorbance value calculated after the maximum uv absorbance is converted to 100%, and the parameters of the abscissa in fig. 8A are

pH

2,3,4,5,6, and 7 of the phosphate buffer, respectively; the abscissa parameters in FIG. 8B show reaction times of 5,10,15,20,25,30,35 minutes, respectively; the abscissa parameters in FIG. 8C are reaction temperatures of 20,30,40,50,60,70 ℃ respectively; the abscissa parameters in FIG. 8D are TMB concentrations of 2,4,6,8,10, and 14mM, respectively. The specific method of performance evaluation in fig. 8A may be: mu.L of OCN suspension obtained from sample 1 at a concentration of 1mg/L, and 30. mu.L of 8mM TMB solution at a concentration of 400. mu.L of 0.1M PBS at

pH

2,3,4,5,6,7, respectively, were added to a 2mL centrifuge tube, vortexed for 30 seconds to mix the solution thoroughly, followed by 50. mu.L of LH₂O₂(500 mu M), placing the centrifugal tube in a constant-temperature water bath shaking table, shaking and incubating for 30 minutes at 40 ℃, and adding 20 mu LH₂SO₄(2M) the reaction was stopped and the color of the solution changed from blue to yellow. Finally, the tube was centrifuged at 13000 rpm for 10 minutes, and the supernatant was taken out and the intensity of the absorption peak at 450nm was recorded by an ultraviolet spectrophotometer. Fig. 8B, 8C, 8D are similar to fig. 8A, with only the corresponding evaluation variables changed. As can be seen from FIG. 8, the reaction pH was 3.0 to 4.0, the reaction temperature was 30 to 40 ℃, the reaction time was 15 to 25min, and when the TMB concentration was 6 to 10mM, the catalytic activity of sample 1 was high, and when the reaction pH was 4.0, the reaction temperature was 40 ℃, the reaction time was 15min, and the TMB concentration was 8mM, the reaction time was 15minSample 1, therefore, had the highest catalytic activity.

The invention is further illustrated by the following spiking recovery experiments performed when the oxygen-doped carbon nitride is used to detect hydrogen peroxide.

mu.L of OCN (1mg/L) from

sample

1, and 30. mu.L of TMB (8mM), 400. mu.L of LPBS (0.1M, pH4.0) solution were pipetted into a 2mL centrifuge tube, vortexed for 30 seconds to mix the solution thoroughly, and then 50. mu.L of a solution of 20. mu. M H added₂O₂Or adding 50 μ L of milk with 40 μ M H₂O₂The mixed solution is placed in a constant-temperature water bath shaking bed to be incubated for 15 minutes at 40 ℃ with shaking. After the reaction is finished, 20 mu LH is added respectively₂SO₄(2M) the reaction was stopped and the color of the solution changed from blue to yellow. And finally, centrifuging the centrifuge tube at 13000 r/min for 5min, taking out supernatant, recording the absorption peak intensity at 450nm by using an ultraviolet spectrophotometer, and comparing with a standard curve to obtain the recovery rates of 96.89-102.81% and 97.87-101.91% by calculation.

The interference immunity of the oxygen-doped carbon nitride in detecting hydrogen peroxide is further illustrated below.

As shown in FIG. 9, 20. mu.L of OCN suspension (1mg/L) obtained from

sample

1, and 30. mu.L of TMB solution (8mM), 400. mu.L of PBS (0.1M, pH4.0) were pipetted into a 2mL centrifuge tube, the solution was mixed well by vortexing for 30s, 50. mu.L of different targets, 200. mu.M hydrogen peroxide and 2mM sodium chloride, 200. mu.M hydrogen peroxide and 2mM potassium chloride, 200. mu.M hydrogen peroxide and 2mM ascorbic acid, 200. mu.M hydrogen peroxide and 2mM cysteine, respectively, were added, and the centrifuge tube was incubated in a constant temperature water bath shaker at 40 ℃ for 15 minutes. After the reaction is finished, 20 mu LH is added₂SO₄(2M) the reaction was stopped and the color of the solution changed from blue to yellow. Finally, the centrifuge tube was centrifuged at 13000 rpm for 10 minutes, and the supernatant was taken out and recorded with an ultraviolet spectrophotometerThe intensity of the absorption peak at 450nm is recorded. The ordinate in fig. 9 represents the absorbance intensity of the solution at 450nm, and it can be seen that even if hydrogen peroxide coexists with other common interferents at a concentration 10 times higher than that of the solution, the absorbance intensity does not change significantly, and the addition of other interferents does not affect the colorimetric detection, thereby showing good selectivity.

The method for detecting the content of the hydrogen peroxide by the oxygen-doped carbon nitride oxygen colorimetric sensor has the advantages of quick detection, low cost, high sensitivity, lower detection limit than most colorimetric sensors on the market at present and good anti-interference performance. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

While the invention has been described with respect to a preferred embodiment, it will be understood by those skilled in the art that the foregoing and other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention. Those skilled in the art can make various changes, modifications and alterations without departing from the spirit and scope of the present invention, and all equivalent changes, modifications and alterations to the present invention are equivalent embodiments of the present invention; meanwhile, any changes, modifications and variations of the above-described embodiments, which are equivalent to those of the technical spirit of the present invention, are within the scope of the technical solution of the present invention.

Claims

1. A method for detecting the content of hydrogen peroxide is characterized by comprising the following steps: the method comprises the following steps:

providing a carbon nitride colorimetric sensor doped with oxygen;

mixing the oxygen-doped carbon nitride colorimetric sensor with a 3,3',5,5' -tetramethylbenzidine solution and a phosphate buffer solution, adding a sample to be detected containing hydrogen peroxide for reaction, and adding acid to terminate the reaction to obtain a reaction solution;

and centrifugally separating the reaction solution to obtain supernatant liquid, performing ultraviolet spectrum analysis, and calculating the content of the hydrogen peroxide according to a standard curve.

2. The method of claim 1, wherein: the oxygen-doped carbon nitride colorimetric sensor is prepared by acid treatment after calcination of a nitrogen-carbon precursor, wherein the nitrogen-carbon precursor is any one of melamine and urea, the acid contains nitric acid and sulfuric acid, and the volume ratio of the nitric acid to the sulfuric acid is (1:1) - (3: 1).

3. The method of claim 2, wherein: the oxygen content of the oxygen-doped carbon nitride colorimetric sensor is 12-16%.

4. The method of claim 2, wherein: the acid treatment time is 0.5-2 hours.

5. The method of claim 1, wherein: the reaction time is 15-25 minutes.

6. The method of claim 1, wherein: the reaction temperature is 30-40 ℃.

7. The method of claim 1, wherein: the pH value of the phosphate buffer solution is 3.0-4.0.

8. The method of claim 1, wherein: the concentration of the 3,3',5,5' -tetramethyl benzidine solution is 6-10 mM.

9. The method of claim 1, wherein: the linear relation R of the standard curve in the range of the hydrogen peroxide concentration of 100 nM-50 uM²>0.99, wherein the detection limit of the hydrogen peroxide is 40-50 nM.

10. The method of claim 1, wherein: the sample to be detected comprises any one of bean products, flour products, meat balls, boiled salted chicken, boiled salted duck and milk.