Method for detecting bromine content in dichlorohydantoin

Abstract

The invention belongs to the technical field of analysis and detection, and discloses a method for detecting the content of bromine in dichlorohydantoin. The method comprises the following steps: mixing dichlorohydantoin, alkali and water to obtain a dichlorohydantoin solution; then adding a photocatalyst, and carrying out photodegradation treatment under ultraviolet irradiation to obtain a to-be-detected solution; adding a buffer solution, a chloramine T solution, a color developing agent and a sodium thiosulfate solution into the to-be-detected solution, determining absorbance by adopting an ultraviolet-visible spectrophotometric method after volume metering, and calculating according to the standard curve to obtain the content of bromine in dichlorohydantoin. According to the method, the dichlorohydantoin solution is treated by adopting a photodegradation method, so that the dichlorohydantoin is quickly decomposed, and detection elements are released in an ion form to adapt to subsequent testing. The photodegradation is applied to the pretreatment process of the dichlorohydantoin sample for the first time, the method for detecting the bromine content in the dichlorohydantoin, which is low in cost, simple and accurate to operate and good in repeatability, is developed, and powerful support is provided for quality control of the dichlorohydantoin.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical detection, and particularly to a method for detecting the bromine content in dichlorohydantoin. Background Art

[0002] Dichlorohydantoin, with the chemical name of 1,3-dichloro-5,5-dimethylhydantoin, is a chloramine-type disinfectant and bactericide, which has the advantages of high active chlorine content, light odor, mild action, and less public hazards caused by environmental pollution; it is also an important chemical product and is used as a chlorinating agent in pharmaceutical and chemical industries. Bromine is a common impurity in dichlorohydantoin. Although the content is low, it still affects the purity, quality and subsequent applications of dichlorohydantoin.

[0003] At present, neither the Chinese Pharmacopoeia (Ch.P.) nor the national standard for dichlorohydantoin (GB / T 23856-2009) includes a method for detecting the bromine content in dichlorohydantoin, and there is no prior art disclosing its detection method. When detecting bromine in dichlorohydantoin, the quality of the pretreatment process directly affects the accuracy of the determination result. Commonly used sample pretreatment methods include wet digestion method and dry ashing method. However, both methods require the use of corrosive reagents or high-temperature processes, with high energy consumption, and will produce a large amount of waste liquid, waste gas, etc., which do not meet the requirements of green environmental protection.

[0004] Therefore, in order to better and more accurately control the impurities in the product and ensure the quality, it is of great significance to develop an efficient and green pretreatment method for the detection of impurities in dichlorohydantoin. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for detecting the bromine content in dichlorohydantoin, so as to solve the problem that there is no recorded detection method for the bromine content in dichlorohydantoin in the prior art.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a method for detecting the bromine content in dichlorohydantoin, comprising the following steps:

[0008] Mix dichlorohydantoin, alkali and water to obtain a dichlorohydantoin solution; add a photocatalyst to the dichlorohydantoin solution, and carry out photocatalytic degradation treatment under ultraviolet light irradiation to obtain a test solution;

[0009] Add a buffer solution, a chloramine T solution, a color reagent, and a sodium thiosulfate solution to the test solution, and after volume fixing, measure the absorbance by ultraviolet-visible spectrophotometry, and calculate the bromine content in dichlorohydantoin according to the standard curve from the absorbance.

[0010] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the mass ratio of dichlorohydantoin to alkali is 1:0.5 - 5; the dosage ratio of dichlorohydantoin to water is 0.001 - 1 g:5 - 30 mL.

[0011] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the concentration of the photocatalyst in the dichlorohydantoin solution is 0.5 - 50 mg / mL.

[0012] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the alkali includes one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0013] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the time for the photocatalytic degradation treatment is 1 - 24 h.

[0014] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the dosage ratio of dichlorohydantoin, buffer solution, chloramine T solution, color reagent, and sodium thiosulfate solution is 0.001 - 1 g:2 - 5 mL:1 mL:1 mL:1 - 10 mL.

[0015] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the buffer solution is an acetic acid - sodium acetate buffer solution with pH = 5; the concentration of the chloramine T solution is 10 g / L; the color reagent is a phenol red solution with a concentration of 1.2 g / L; the concentration of the sodium thiosulfate solution is 125 g / L.

[0016] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the wavelength for the ultraviolet - visible spectrophotometric determination is 590 nm.

[0017] Preferably, in the above method for detecting the bromine content in dichlorohydantoin, the method for drawing the standard curve is as follows: Prepare bromine standard solutions with different concentrations, add buffer solution, chloramine T solution, color reagent, and sodium thiosulfate solution to the bromine standard solutions respectively, and after volume - fixing, measure the absorbance by ultraviolet - visible spectrophotometry; use the concentration of the bromine standard solution as the abscissa and the absorbance as the ordinate to draw the standard curve.

[0018] From the above - mentioned technical solutions, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0019] Combining with the chemical property that dichlorohydantoin is unstable to light, the present invention designs a mild pretreatment process: compound dichlorohydantoin and an alkali, and use the method of photocatalysis degradation to treat the compound solution of dichlorohydantoin, so that dichlorohydantoin decomposes rapidly, and the detected elements are released in the form of ions to adapt to subsequent tests. Further, the bromine content in dichlorohydantoin is determined by ultraviolet-visible spectrophotometry. The present invention applies photocatalysis degradation to the pretreatment process of dichlorohydantoin samples for the first time, and develops a detection method for the bromine content in dichlorohydantoin with low cost, simple operation, accuracy and good repeatability, which provides strong support for the quality control of dichlorohydantoin. Specific Embodiments

[0020] The present invention provides a method for detecting the bromine content in dichlorohydantoin, comprising the following steps:

[0021] Mix dichlorohydantoin, an alkali and water to obtain a dichlorohydantoin solution; add a photocatalyst to the dichlorohydantoin solution, and carry out photocatalysis degradation treatment under ultraviolet light irradiation to obtain a test solution;

[0022] Add a buffer solution, a chloramine T solution, a color reagent and a sodium thiosulfate solution to the test solution, and after constant volume, measure the absorbance by ultraviolet-visible spectrophotometry, and calculate the bromine content in dichlorohydantoin according to the standard curve from the absorbance.

[0023] In the present invention, the mass ratio of dichlorohydantoin to the alkali is preferably 1:0.5 - 5, further preferably 1:0.8 - 3, and more preferably 1:1; the dosage ratio of dichlorohydantoin to water is preferably 0.001 - 1 g:5 - 30 mL, further preferably 0.01 - 0.5 g:10 - 30 mL, and more preferably 0.1 g:20 mL.

[0024] In the present invention, the alkali preferably includes one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, further preferably sodium hydroxide or potassium hydroxide, and more preferably sodium hydroxide.

[0025] In the present invention, the water is preferably ultrapure water.

[0026] In the present invention, the concentration of the photocatalyst in the dichlorohydantoin solution is preferably 0.5 - 50 mg / mL, further preferably 1 - 20 mg / mL, and more preferably 5 mg / mL.

[0027] In the present invention, the photocatalyst preferably includes one of titanium dioxide and zinc oxide, further preferably titanium dioxide, and more preferably P25.

[0028] In the present invention, the light source of the ultraviolet light preferably includes one of a xenon lamp, a deuterium lamp, and an LED lamp, more preferably a xenon lamp or an LED lamp, and still more preferably a xenon lamp. The light source used in the examples of the present invention is purchased from Beijing Zhongjiao Jinyuan Technology Co., Ltd., CEL-HXF300-S photocatalytic xenon lamp light source.

[0029] In the present invention, the time of the photocatalytic degradation treatment is preferably 1 to 24 h, more preferably 2 to 12 h, and still more preferably 4 h; stirring is also included during the photocatalytic degradation treatment; the rotation speed of the stirring is preferably 800 rpm.

[0030] In the present invention, the dosage ratio of dichlorohydantoin, buffer solution, chloramine T solution, color reagent, and sodium thiosulfate solution is preferably 0.001 to 1 g: 2 to 5 mL: 1 mL: 1 mL: 1 to 10 mL, more preferably 0.01 to 0.5 g: 2 to 4 mL: 1 mL: 1 mL: 2 to 6 mL, and still more preferably 0.1 g: 2 mL: 1 mL: 1 mL: 5 mL.

[0031] In the present invention, the buffer solution is preferably an acetic acid-sodium acetate buffer solution with pH = 5; the concentration of the chloramine T solution is preferably 10 g / L; the color reagent is preferably a phenol red solution with a concentration of 1.2 g / L; the concentration of the sodium thiosulfate solution is preferably 125 g / L.

[0032] In the present invention, the volume after constant volume is 50 mL.

[0033] In the present invention, the wavelength measured by the ultraviolet-visible spectrophotometry is preferably 590 nm.

[0034] In the present invention, the method for drawing the standard curve is as follows: Prepare bromine standard solutions with different concentrations, add buffer solution, chloramine T solution, color reagent, and sodium thiosulfate solution to the bromine standard solutions respectively, measure the absorbance by ultraviolet-visible spectrophotometry after constant volume; use the concentration of the bromine standard solution as the abscissa and the absorbance as the ordinate to draw the standard curve.

[0035] In the present invention, the method for preparing the bromine standard solutions with different concentrations is as follows: Respectively transfer 0, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, and 1.0 mL of a bromine mother liquor with a concentration of 500 μg / mL into 6 50-mL colorimetric tubes, and make up to 50 mL to obtain bromine standard solutions with different concentrations.

[0036] In the present invention, the equation of the standard curve is: A = a×C + b; where A is the absorbance of the bromine standard solution and C is the concentration of the bromine standard solution.

[0037] In the present invention, the formula for calculating the bromine content in dichlorohydantoin based on the absorbance according to the standard curve is:

[0038] Wherein, ω is the bromine content in dichlorohydantoin, A' is the absorbance of the test solution, and m is the mass (g) of dichlorohydantoin.

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Example 1

[0041] (1) Accurately weigh 0.1000 g of dichlorohydantoin product into a light tube, add 20 mL of ultrapure water and 0.1 g of sodium hydroxide, and stir well to dissolve; add 0.1 g of P25 to the light tube; after sealing the light tube, place it in a photocatalytic device and irradiate with ultraviolet light for 4 h under stirring at 800 rpm to obtain a test solution;

[0042] (2) Transfer 0, 0.20 mL, 0.40 mL, 0.60 mL, 0.80 mL, and 1.00 mL of bromine mother liquor with a concentration of 500 μg / mL into 6 50-mL colorimetric tubes respectively, and add 2 mL of acetic acid-sodium acetate buffer solution with pH = 5.0, 1 mL of 10 g / L chloramine T solution, 1 mL of color reagent (1.2 g / L phenol red solution), and 1 mL of 125 g / L sodium thiosulfate solution to each colorimetric tube; make up the volume to 50 mL and measure the absorbances at 590 nm by ultraviolet-visible spectrophotometry as follows: A1 = 0.471, A2 = 0.610, A3 = 0.828, A4 = 1.078, A5 = 1.304, and A6 = 1.474, and draw a standard curve as A = 0.10881C + 0.40776;

[0043] (3) Add 2 mL of acetic acid-sodium acetate buffer solution with pH = 5.0, 1 mL of 10 g / L chloramine T solution, 1 mL of color reagent (1.2 g / L phenol red solution), and 5 mL of 125 g / L sodium thiosulfate solution to the test solution; make up the volume to 50 mL and measure the absorbance at 590 nm by ultraviolet-visible spectrophotometry as A' = 1.030, and substitute it into the formula to calculate that the bromine content in dichlorohydantoin is 0.2859%.

[0044] Example 2

[0045] Precision experiment: Perform 3 parallel experiments on the same sample, calculate the RSD, and require that the RSD of the results of 3 parallel experiments ≤ 20.0%.

[0046] According to the method of Example 1, repeat it 2 more times. Take Example 1 as Parallel Experiment 1, and repeat it 2 times respectively as Parallel Experiment 2 and Parallel Experiment 3. The experimental results are shown in Table 1.

[0047] Table 1 Results of Precision Experiment

[0048]

[0049] Example 3

[0050] Spiked Recovery Experiment: By adding different volumes of bromine standard solution to the test solution, investigate the influence of the added amount on the measurement result. It is required that the recovery rate of bromine should be between 90.0% and 110.0% before and after adding the sample. The experimental results are shown in Table 2.

[0051] Table 2 Results of Spiked Recovery Experiment

[0052]

[0053]

[0054] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting the bromine content in dichlorohydantoin, characterized in that, It includes the following steps: Mix dichlorohydantoin, alkali and water to obtain a dichlorohydantoin solution; Add a photocatalyst to the dichlorohydantoin solution and carry out photocatalytic degradation treatment under ultraviolet light irradiation to obtain a test solution; Add a buffer solution, chloramine T solution, color reagent and sodium thiosulfate solution to the test solution. After volume fixing, measure the absorbance by ultraviolet-visible spectrophotometry, and calculate the bromine content in dichlorohydantoin according to the standard curve.

2. The detection method of bromine content in dichlorohydantoin according to claim 1, characterized in that, The mass ratio of the dichlorohydantoin to the alkali is 1:0.5 - 5; the dosage ratio of the dichlorohydantoin to water is 0.001 - 1 g:5 - 30 mL.

3. The detection method of bromine content in dichlorohydantoin according to claim 2, characterized in that, The concentration of the photocatalyst in the dichlorohydantoin solution is 0.5 - 50 mg / mL.

4. The detection method of bromine content in dichlorohydantoin according to claim 3, characterized in that, The alkali includes one of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

5. The detection method of bromine content in dichlorohydantoin according to claim 1 or 3, characterized in that, The time of the photocatalytic degradation treatment is 1 - 24 h.

6. The detection method of bromine content in dichlorohydantoin according to claim 5, characterized in that The dosage ratio of the dichlorohydantoin, buffer solution, chloramine T solution, color reagent and sodium thiosulfate solution is 0.001 - 1 g:2 - 5 mL:1 mL:1 mL:1 - 10 mL.

7. The detection method of bromine content in dichlorohydantoin according to claim 6, characterized in that, The buffer solution is an acetic acid - sodium acetate buffer solution with pH = 5; the concentration of the chloramine T solution is 10 g / L; the color reagent is a phenol red solution with a concentration of 1.2 g / L; the concentration of the sodium thiosulfate solution is 125 g / L.

8. A method for detecting the bromine content in dichlorohydantoin according to claim 7, characterized in that, The wavelength measured by the ultraviolet-visible spectrophotometry is 590 nm.

9. The detection method of bromine content in dichlorohydantoin according to claim 1 or 8, characterized in that The method for drawing the standard curve is: prepare bromine standard solutions with different concentrations, add a buffer solution, chloramine T solution, color reagent and sodium thiosulfate solution to the bromine standard solutions respectively. After volume fixing, measure the absorbance by ultraviolet-visible spectrophotometry; use the concentration of the bromine standard solution as the abscissa and the absorbance as the ordinate to draw the standard curve.

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