A reagent and method for detecting low concentrations of methanol in water

Abstract

This application discloses a reagent and method for detecting low concentrations of methanol in water. The reagent includes reagent A, reagent B, and reagent C. Reagent A is a hydrogen peroxide solution, reagent B is a catalytic stabilizer, and reagent C is a guanidine acid solution. This application utilizes spectrophotometry to determine the methanol concentration in water, with a detection range of 0-20 mg / L and a detection limit of 0.1 mg / L. Its sensitivity is higher than other current spectrophotometric methods for methanol determination, representing a domestic first. It is convenient to operate and suitable for rapid detection of methanol in water.

Description

Technical Field

[0001] This application relates to the field of methanol detection technology in water bodies, specifically to a reagent and method for detecting low concentrations of methanol in water bodies. Background Technology

[0002] Methanol is a colorless, transparent, and flammable liquid with strong volatility and irritant properties. It has wide applications in industry, medicine, and pesticides. However, methanol poses potential health hazards to humans. When methanol enters water bodies, it negatively impacts aquatic ecosystems. For example, methanol in water can affect the growth and reproduction of fish, algae, and other aquatic organisms; high concentrations may lead to the death of aquatic life. It can also alter the chemical properties of water bodies, potentially causing water quality deterioration. Furthermore, it can affect human health through the food chain. Therefore, accurate and reliable measurement of methanol concentration in water bodies is essential to strictly control the methanol content in industrial and agricultural wastewater to meet discharge standards. For instance, the "Shanghai Integrated Wastewater Discharge Standard" (DB31199-2018) clearly stipulates the methanol content limits in wastewater, requiring that the methanol limit for Grade I water be below 3 mg / L, Grade II water below 8 mg / L, and Grade III water below 10 mg / L (see Table 1).

[0003] Table 1

[0004]

[0005] Among traditional methods for methanol detection in water bodies, gas chromatography can achieve a low detection limit, meeting the requirements for methanol discharge standards. However, chromatographic instruments are expensive, routine maintenance is cumbersome, and the detection method itself is relatively complex, making it unsuitable for on-site testing. Spectrophotometry is commonly used for methanol detection in alcoholic beverages, such as the chromotropic acid method, fuchsin method, and acetylacetone method. However, their detection limits are high, all within the range of 200-600 mg / L. Directly applying them to water body detection cannot meet the requirements for water body discharge standards. Existing methanol standard detection methods, detection limits, and application scenarios are shown in Table 2.

[0006] Table 2. Methods for detecting methanol content in existing standard methods.

[0007]

[0008] Therefore, based on the current status of methanol detection, there is an urgent need to develop a convenient, fast, and low-limit detection product and method for detecting low-concentration methanol in water bodies, in order to meet the higher requirements for methanol discharge compliance in wastewater. Summary of the Invention

[0009] This application provides a reagent and method for detecting low concentrations of methanol in water, with a detection range of 0-20 mg / L and a detection limit of 0.1 mg / L. The sensitivity is higher than other existing spectrophotometric methods for methanol determination. This method is the first of its kind in China and is convenient to operate, making it suitable for rapid detection of low concentrations of methanol in water.

[0010] A reagent for detecting low concentrations of methanol in water comprises reagents A, B, and C, each separately packaged. Reagent A is a hydrogen peroxide solution, reagent B is a catalytic stabilizer, and reagent C is a guanidine acid solution.

[0011] The detection principle of the reagent in this application is as follows:

[0012] Reagents A and B work together to oxidize methanol in water. The oxide reacts with reagent C in the presence of reagent A to form a blue-green compound, which is then measured colorimetrically at 620 nm.

[0013] This application utilizes the principle of spectrophotometry to determine the concentration of methanol in water. The detection range is 0-20 mg / L, the detection limit is 0.1 mg / L, and the sensitivity matching is comparable to gas chromatography, which is superior to other related spectrophotometric methods for methanol determination. This is the first of its kind in China, and it is easy to operate and suitable for rapid detection of low concentrations of methanol (0-20 mg / L) in water.

[0014] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0015] Optionally, the mass percentage concentration of the hydrogen peroxide solution is 0.1-10%.

[0016] Optionally, the catalytic stabilizer is an aqueous solution of zinc acetate, zinc sulfate, zinc nitrate, zinc chloride, or zinc fluoroborate, with a mass percentage concentration of 3-30%.

[0017] Optionally, the guanidine reagent in the acid solution has a mass percentage concentration of 0.1%-10% and a hydrogen ion concentration of 0.01mol / L-1mol / L.

[0018] Optionally, the acid solution in the guanidine reagent acid solution can be hydrochloric acid, sulfuric acid, acetic acid, or phosphoric acid.

[0019] Optionally, the guanidine reagent in the guanidine reagent acid solution is 1-(benzo[d]thiazol-2-yl)guanidine, with the molecular formula C8H8N4S.

[0020] More preferably, reagent A is a hydrogen peroxide solution with a mass percentage concentration of 0.1%-2%; reagent B is a zinc acetate solution with a mass percentage concentration of 10-15%; and reagent C is a 1-(benzo[d]thiazol-2-yl)guanidine hydrochloric acid solution with a mass percentage concentration of 0.5-2% and a hydrogen ion concentration of 0.1 mol / L-0.3 mol / L.

[0021] This application also provides a method for detecting low concentrations of methanol in water using the aforementioned reagent, comprising:

[0022] (1) Take a water sample for testing, add reagent A and reagent B, mix well and react at 55-60℃ for 4-6 min, then add reagent C, mix well and react at 90-100℃ for 4-6 min to obtain the reaction solution;

[0023] (2) Measure the absorbance of the reaction solution at 620 nm, substitute the obtained absorbance value into the standard curve, and calculate the methanol concentration in the water sample.

[0024] Optionally, based on a 5 mL sample of water to be tested, the amount of reagent A added is 0.2-0.5 mL, reagent B is 0.2-0.5 mL, and reagent C is 0.2-0.5 mL.

[0025] Optionally, reagent A and reagent B are added, mixed, and reacted at 56°C for 5 min. Then reagent C is added, mixed, and reacted at 100°C for 5 min.

[0026] The preferred test reagent:

[0027] Reagent A is a hydrogen peroxide solution with a mass percentage concentration of 1%; Reagent B is an aqueous solution of zinc acetate with a mass percentage concentration of 12%; Reagent C is a 1-(benzo[d]thiazol-2-yl)guanidine hydrochloric acid solution with a mass percentage concentration of 1% and a hydrogen ion concentration of 0.2 mol / L.

[0028] Under optimal detection reagent conditions, the optimal determination process is as follows:

[0029] Take 5 mL of water sample into a colorimetric tube, add 0.5 mL of reagent A and 0.5 mL of reagent B, cap the tube, and react at 56℃ for 5 minutes. Then open the cap, add 0.5 mL of reagent C, and let it stand at 100℃ for 5 minutes. After cooling, measure the color.

[0030] Compared with the prior art, this application has at least one of the following beneficial effects:

[0031] (1) The detection range is 0-20 mg / L, the detection limit is 0.1 mg / L, and the sensitivity is higher than other related spectrophotometric methods for methanol determination. It is suitable for rapid detection of low concentrations of methanol in water.

[0032] (2) The detection process is simple, the test reagents are easy to carry, and it is suitable for on-site testing. Attached Figure Description

[0033] Figure 1 This is a full-band scan of the methanol standard solution at 0-20 ppm in Example 1.

[0034] Figure 2 This is a standard curve of methanol prepared in Example 1.

[0035] Figure 3 This is a color development result diagram of Example 3.

[0036] Figure 4 This is a color development result diagram of Example 4.

[0037] Figure 5 This is a color development result diagram of Example 5. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0040] The following describes a preferred embodiment in detail:

[0041] Example 1

[0042] I. Treatment reagents:

[0043] Reagent A: Hydrogen peroxide solution (1%); Reagent B: Zinc acetate aqueous solution (12%); Reagent C: 1-(benzo[d]thiazol-2-yl)guanidine hydrochloric acid solution (guanidine reagent 1% - hydrochloric acid 0.2mol / L). The solvent used in preparing or diluting the reagents is water.

[0044] II. Standard solution gradient:

[0045] Methanol standard stock solution (10 g / L):

[0046] Pipette 1.26 mL of methanol with a density of 0.7913 g / mL (i.e., weigh 1 g of methanol) into a 100 mL volumetric flask, and dilute to volume with pure water. This 1 mL solution is equivalent to containing 10 mg of methanol. Store at low temperature.

[0047] Methanol standard working solution (100 mg / L):

[0048] Pipette 1 mL of methanol standard stock solution (10 g / L) into a 100 mL volumetric flask and dilute to the mark with pure water to obtain a 100 PPM standard solution.

[0049] Table 3 shows the gradient preparation process of the standard solutions. The standard gradient solutions should be prepared from high concentration to low concentration, i.e., from No. 8 to No. 1.

[0050] Table 3

[0051]

[0052] III. Testing Process:

[0053] Creating a standard curve:

[0054] (1) Turn on the DR-3900 photometer (Hach Corporation, USA) and the LH-TX6 digester (Zhejiang Luheng Environmental Technology Co., Ltd.), select the measurement wavelength as 620 nm, and zero it with pure water.

[0055] (2) Accurately transfer 5 mL of standard sample into a colorimetric tube and mix well.

[0056] (3) Add 0.5 mL of reagent A and 0.5 mL of reagent B respectively, cover and shake well, and react at 56℃ for 5 min.

[0057] (4) Add 0.5 mL of reagent C and mix well at 100℃ for 5 min.

[0058] Steps (3) and (4) are both performed in a digester LH-TX6.

[0059] (5) Cool the colorimetric tube to room temperature, place it in the DR3900 instrument, and read its absorbance value.

[0060] (6) After the test, press and hold the power button to turn off the DR3900 instrument.

[0061] Full-band scanning was performed on standard solutions ranging from 0 to 20 ppm (Table 3), and the results are shown below. Figure 1 ,according to Figure 1 As a result, the reaction solution has the highest absorption peak at around 620 nm.

[0062] The absorbance measurement results at 620 nm are shown in Table 4, and the standard curve is as follows: Figure 2 The linear equation is: y = 9.8686x - 0.1726, R0 2 =0.999, where x is the concentration of methanol in the water sample in mg / L, and y is the absorbance value of the reaction solution at 620 nm. This indicates that the detection reagent and method of this application have a good linear relationship with low concentrations of methanol in water, and can accurately quantify low concentrations of methanol in water. The linear detection range is 0-20 mg / L.

[0063] Table 4

[0064]

[0065] Example 2

[0066] Using the test reagent of Example 1 and referring to the test conditions of Example 1, natural water samples were taken and spiked recovery tests were conducted. The test results are shown in Table 5.

[0067] Table 5

[0068]

[0069] As shown in Table 5, the spiked recovery rate is between 90% and 110%, indicating that the method of this application has reliability and good precision for methanol detection in natural water samples.

[0070] Example 3: Screening of Reagent A Dosage

[0071] Using the detection reagent of Example 1 and referring to the detection method of Example 1, 5 mL of 10 ppm methanol standard was taken, and the amount of reagent A was adjusted to 0.1 mL, 0.25 mL, 0.5 mL, 0.75 mL, 1 mL, and 1.25 mL. The detection results under different amounts of reagent A are shown in Table 6, and the colorimetric results are as follows. Figure 3 As shown, from left to right, the values ​​are 0.1 mL, 0.25 mL, 0.5 mL, 0.75 mL, 1 mL, and 1.25 mL.

[0072] Table 6

[0073] A / mL 0.1 0.25 0.5 0.75 1 1.25 Abs620 (10ppm) 0.70 0.97 0.99 0.38 0.07 0.05

[0074] The optimal amount of reagent to use is determined based on the colorimetric reaction of the 10ppm standard solution, with the one showing the highest absorbance being the optimal amount. It can be seen that 0.5 mL is the optimal amount for reagent A.

[0075] Example 4: Screening of Reagent B Dosage

[0076] Using the detection reagent of Example 1 and referring to the detection method of Example 1, 5 mL of 10 ppm methanol standard was taken, and the amount of reagent B was adjusted to 0.25 mL, 0.5 mL, 1 mL, 1.5 mL, and 2 mL. The detection results under different amounts of reagent B are shown in Table 7, and the colorimetric results are as follows. Figure 4 As shown, from left to right, the values ​​are: 0.25 mL, 0.5 mL, 1 mL, 1.5 mL, and 2 mL.

[0077] Table 7

[0078] B / mL 0.25 0.5 1 1.5 2 Abs620 (10ppm) 1.06 1.24 1.02 0.42 0.04

[0079] The optimal amount of reagent to use is determined based on the colorimetric reaction of the 10ppm standard solution, with the one showing the highest absorbance being the optimal amount. It can be seen that 0.5mL is the optimal amount for reagent B.

[0080] Example 5: Screening of Reagent C Dosage

[0081] Using the detection reagent of Example 1 and referring to the detection method of Example 1, 5 mL of 10 ppm methanol standard was taken, and the amount of reagent D was adjusted to 0.25 mL, 0.5 mL, 0.75 mL, 1 mL, and 1.25 mL. The detection results under different amounts of reagent D are shown in Table 9, and the colorimetric results are as follows. Figure 5 As shown, from left to right, the values ​​are: 0.25 mL, 0.5 mL, 0.75 mL, 1 mL, and 1.25 mL.

[0082] Table 8

[0083] C / mL 0.25 0.5 0.75 1 1.25 Abs620 (10ppm) 1.16 1.26 0.27 0.20 0.56

[0084] The optimal amount of reagent to use is determined based on the colorimetric reaction of the 10ppm standard solution, with the one showing the highest absorbance being the optimal amount. It can be seen that 0.5 mL is the optimal amount for reagent C.

[0085] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A reagent for detecting low concentration methanol content in a water body, characterized in that, The product includes separately packaged reagents A, B, and C. Reagent A is a hydrogen peroxide solution, reagent B is a catalytic stabilizer, and reagent C is a guanidine reagent acid solution. The catalytic stabilizer is an aqueous solution of zinc acetate, zinc sulfate, zinc nitrate, zinc chloride, or zinc fluoroborate, with a mass percentage concentration of 3-30%. The guanidine reagent in the guanidine reagent acid solution is 1-(benzo[d]thiazol-2-yl)guanidine.

2. The agent of claim 1, wherein The methanol content in the water body is 0-20 mg / L.

3. The agent of claim 1, wherein The mass percentage concentration of the hydrogen peroxide solution is 0.1-10%.

4. The agent of claim 1, wherein The guanidine reagent in the acid solution has a mass percentage concentration of 0.1%-10% and a hydrogen ion concentration of 0.01mol / L-1mol / L.

5. A method for detecting low concentration of methanol in water using the reagent of claim 1, characterized in that, include: (1) Take a water sample for testing, add reagent A and reagent B, mix well and react at 55-60℃ for 4-6 min, then add reagent C, mix well and react at 90-100℃ for 4-6 min to obtain the reaction solution; (2) Measure the absorbance of the reaction solution at 620 nm, substitute the obtained absorbance value into the standard curve, and calculate the methanol concentration in the water sample.

6. The method of claim 5, wherein, The concentration range of methanol in the tested water samples was 0-20 mg / L.

7. The method according to claim 5, characterized in that, For a 5 mL water sample to be tested, add 0.2-0.5 mL of reagent A, 0.2-0.5 mL of reagent B, and 0.2-0.5 mL of reagent C.

8. The method of claim 5, wherein, After adding reagent A and reagent B, the mixture was reacted at 56°C for 5 minutes. Then, reagent C was added, and after mixing, the mixture was reacted at 100°C for 5 minutes.

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