Reagent and method for detecting content of low-concentration methanol in water body

Abstract

The invention discloses a reagent and method for detecting the content of low-concentration methanol in a water body, the reagent comprises a reagent A, a reagent B and a reagent C, the reagent A is a hydrogen peroxide solution, the reagent B is a catalytic stabilizer, and the reagent C is a guanidine reagent acid solution. The methanol concentration in the water body is measured by utilizing a spectrophotometric principle, the detection range is 0-20mg / L, the detection limit is 0.1 mg / L, the sensitivity is higher than that of other related spectrophotometric analysis methods for measuring methanol at present, the method is pioneered in China, and the method is convenient to operate and suitable for rapid detection of methanol in the water body.

Description

Technical Field

[0001] The present application relates to the technical field of methanol detection in water, and in particular to a detection reagent and method for detecting low-concentration methanol in water. Background Art

[0002] Methanol is a colorless, transparent, flammable liquid with high volatility and irritation. It is widely used in industry, medicine, pesticides and other fields. However, methanol has potential hazards to human health. When methanol enters the water body, it has a negative impact on the aquatic ecosystem. For example, methanol entering the water body may affect the growth and reproduction of fish, algae and other aquatic organisms. High concentrations of methanol may cause the death of aquatic organisms; it may change the chemical properties of the water body and cause water quality to deteriorate; it may be transmitted through the food chain and affect human health. Therefore, it is necessary to accurately and reliably measure the methanol concentration in the water body to strictly control the methanol content of industrial and agricultural wastewater to meet the discharge standards. For example, the "Shanghai Integrated Wastewater Discharge Standard" (DB31199-2018) clearly stipulates the methanol content in wastewater, requiring the methanol limit standard to be below 3 mg / L for first-level water, below 8 mg / L for second-level water, and below 10 mg / L for third-level water. See Table 1:

[0003] Table 1

[0004]

[0005] Among traditional methods for detecting methanol in water, gas chromatography can achieve a low detection limit, meeting the requirements for methanol emissions in water. However, chromatographic instruments are expensive, routine maintenance is cumbersome, and the detection method is relatively complex, making it unsuitable for on-site testing. Spectrophotometry, such as chromotropic acid colorimetry, fuchsin colorimetry, and acetylacetone colorimetry, is commonly used to detect methanol in wine. However, its detection limits are high, ranging from 200 to 600 mg / L. Directly applying these methods to water testing cannot meet the requirements for methanol emissions. Table 2 lists existing standard detection methods for methanol, their detection limits, and application scenarios.

[0006] Table 2 Detection methods of 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-detection-limit low-concentration methanol content detection product and method for water bodies to meet higher wastewater methanol emission standards. Summary of the Invention

[0009] The present application provides a reagent and method for detecting low-concentration methanol content in water bodies, with a detection range of 0-20 mg / L and a detection limit of 0.1 mg / L. The sensitivity is higher than other current related spectrophotometric analytical methods for determining methanol. It is a domestic first, has easy operation, and is suitable for rapid detection of low-concentration methanol content in water bodies.

[0010] A reagent for detecting low-concentration methanol content in water, comprising independently packaged reagent A, reagent B, and reagent C, wherein the reagent A is a hydrogen peroxide solution, the reagent B is a catalytic stabilizer, and the reagent C is a guanidine reagent acid solution.

[0011] The detection principle of this application reagent:

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

[0013] This application uses the principle of spectrophotometry to determine the methanol concentration in water bodies. 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 higher than other related spectrophotometric analytical methods for determining methanol. It is a domestic first, easy to operate, and suitable for rapid detection of low-concentration methanol content (0-20 mg / L) in water bodies.

[0014] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

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

[0018] Optionally, the acid solution in the guanidine reagent acid solution may 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 a molecular formula of C8H8N4S.

[0020] Further 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 hydrochloride 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] The present application also provides a method for detecting low-concentration methanol content in water using the reagent, comprising:

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

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

[0024] Optionally, based on 5 mL of the water sample to be tested, 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 are added.

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

[0026] The most preferred detection reagents:

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

[0028] Under the conditions of the most optimal detection reagents, the most optimal determination process:

[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, cover it, react at 56°C for 5 minutes, then open the cover, add 0.5 mL of reagent C, let it react at 100°C for 5 minutes, and compare the color after cooling.

[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, and the detection limit is 0.1 mg / L. The sensitivity is higher than that of other relevant spectrophotometric analytical methods for the determination of methanol. It is suitable for the rapid detection of low-concentration methanol in water.

[0032] (2) The detection process is simple, the detection reagents are easy to carry, and are suitable for on-site detection. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0034] Figure 2 This is the methanol standard curve diagram produced in Example 1.

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

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

[0037] Figure 5 This is the color development result diagram of Example 5. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts 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 those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0040] The following is a specific description based on preferred embodiments:

[0041] Example 1

[0042] 1. 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 hydrochloride solution (guanidine reagent 1%-hydrochloric acid 0.2 mol / L). The solvent used for preparation or dilution of the reagents was water.

[0044] 2. 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 100 PPM standard solution.

[0049] Table 3 shows the gradient preparation process of the standard solution, in which the standard gradient solution should be prepared from high concentration to low concentration, that is, from No. 8 to No. 1.

[0050] Table 3

[0051]

[0052] 3. Testing process:

[0053] Preparation of standard curve:

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

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

[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°C for 5 min.

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

[0058] Steps (3) and (4) are both carried out in the digester LH-TX6.

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

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

[0061] The 0-20ppm standard solution (Table 3) was scanned in the full band, and the results are shown in Figure 1 ,according to Figure 1 As a result, the reaction solution has the highest absorption peak at around 620nm.

[0062] The absorbance measurement results at 620 nm are shown in Table 4, and the standard curve is shown in Figure 2 , linear equation: y = 9.8686x - 0.1726, R 2 =0.999, where x is the methanol concentration in the test water sample in mg / L, and y is the absorbance value of the reaction solution at 620 nm, indicating that there is a good linear relationship between the detection reagent and method of the present application and low concentrations of methanol in water, and low concentrations of methanol in water can be accurately and quantitatively determined, with a linear detection range of 0-20 mg / L.

[0063] Table 4

[0064]

[0065] Example 2

[0066] The detection reagent of Example 1 was used, and the detection conditions of Example 1 were referred to. Natural water samples were taken and spike recovery tests were performed. The test results are shown in Table 5.

[0067] Table 5

[0068]

[0069] According to the spiked recovery rates in Table 5, the spiked recovery rates are between 90% and 110%, indicating that the methanol detection results of the present method for natural water samples are reliable and have good precision.

[0070] Example 3 Reagent A dosage screening

[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 respectively. The detection results under different amounts of reagent A are shown in Table 6. The color development results are shown in Table 6. Figure 3 As shown, from left to right they 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 dosage of the reagent is determined based on the color reaction of the 10 ppm standard solution. The optimal dosage is the one with the highest absorbance. It can be seen that 0.5 mL of reagent A is the best.

[0075] Example 4 Reagent B dosage screening

[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 respectively. The detection results under different amounts of reagent B are shown in Table 7. The color development results are shown in Table 7. Figure 4 As shown, from left to right: 0.25 mL, 0.5 mL, 1 mL, 1.5 mL, 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 dosage of the reagent is determined based on the color reaction of the 10 ppm standard solution. The one with the largest absorbance is the optimal dosage. It can be seen that 0.5 mL of reagent B is the best.

[0080] Example 5 Reagent C dosage screening

[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 respectively. The detection results under different amounts of reagent D are shown in Table 9. The color development results are shown in Table 9. Figure 5 As shown, from left to right: 0.25 mL, 0.5 mL, 0.75 mL, 1 mL, 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 dosage of the reagent is determined based on the color reaction of the 10 ppm standard solution. The one with the highest absorbance is the optimal dosage. It can be seen that 0.5 mL of reagent C is the best.

[0085] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A reagent for detecting low-concentration methanol content in water, characterized in that: The invention comprises reagent A, reagent B and reagent C which are separately packaged. Reagent A is a hydrogen peroxide solution, reagent B is a catalytic stabilizer, and reagent C is a guanidine reagent acid solution.

2. The reagent according to claim 1, characterized in that The methanol content in the water body is 0-20 mg / L.

3. The reagent according to claim 1, characterized in that The mass percentage concentration of the hydrogen peroxide solution is 0.1-10%.

4. The reagent according to claim 1, characterized in that 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%.

5. The reagent according to claim 1, characterized in that The mass percentage concentration of the guanidine reagent in the guanidine reagent acid solution is 0.1%-10%, and the hydrogen ion concentration is 0.01 mol / L-1 mol / L.

6. The reagent according to claim 1, characterized in that The guanidine reagent in the guanidine reagent acid solution is 1-(benzo[d]thiazol-2-yl)guanidine.

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

8. The method according to claim 7, characterized in that The concentration range of methanol in the test water sample is 0-20 mg / L.

9. The method according to claim 7, characterized in that Based on 5 mL of 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.

10. The method according to claim 7, characterized in that Reagent A and reagent B were added, mixed, and reacted at 56° C. for 5 minutes. Then, reagent C was added, mixed, and reacted at 100° C. for 5 minutes.

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