CN110261376B

CN110261376B - Solution and method for removing interference of ammonium ions on color reaction in water sample cyanide content determination process

Info

Publication number: CN110261376B
Application number: CN201910640554.0A
Authority: CN
Inventors: 于晓章; 林钰涓
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2019-07-16
Filing date: 2019-07-16
Publication date: 2021-10-29
Anticipated expiration: 2039-07-16
Also published as: CN110261376A

Abstract

The invention discloses a solution and a method for removing interference of ammonium ions on a color reaction in a water sample cyanide content determination process, and the solution and the method are used for removing water sample cyanide CN^‑The solution of which the color reaction is interfered by ammonium ions in the content determination process is prepared from KH₂PO₄Solution, H₃BO₃Solution and NH₄And mixing the Cl solution, wherein the concentration of each component after mixing is as follows: KH (Perkin Elmer)₂PO₄30～40mg/L、H₃BO₃0.10～0.15mg/L、NH₄100-150 mg/L of Cl. Determination of CN in water sample by isonicotinic acid-pyrazolone colorimetric method^‑When the content is measured, in the process of obtaining a cyanide standard curve, adding a solution for removing the interference of ammonium ions on the color reaction in the process of measuring the cyanide content of the water sample to correct the standard curve, so that CN in the water sample determined by the corrected standard curve^‑The content is not interfered by ammonium ions, and the problem that the accuracy of the measurement result is influenced by the ammonium ions is solved.

Description

Solution and method for removing interference of ammonium ions on color reaction in water sample cyanide content determination process

Technical Field

The invention belongs to the field of chemical detection, and relates to a method for removing simple Cyanide (CN) in a water sample determined by an isonicotinic acid-pyrazolone colorimetric method^-) A solution and a method for interfering the color reaction by ammonium ions in the content process.

Background

Simple Cyanide (CN)^-) Belongs to a highly toxic chemical substance, and the emission limit value is 0.5mg/L in the integrated wastewater discharge standard GB 8978 + 1996. The existing method for measuring the content of cyanide in a water sample mainly comprises a silver nitrate titration method, an isonicotinic acid-pyrazolone colorimetric method, an isonicotinic acid-barbituric acid spectrophotometry and the like. The isonicotinic acid-pyrazolone colorimetric method is the most common determination method, and the detection mechanism is as follows: under the neutral condition, chloramine T reacts with cyanide in a water sample to generate cyanogen chloride, the cyanogen chloride reacts with isonicotinic acid to be hydrolyzed to generate glutaconide, and finally the glutaconide is condensed with pyrazolone to generate blue dye, and the content of simple cyanide in the water sample is determined by determining the absorbance value at 638 nm. The method is applicable to the determination of simple cyanide in drinking water, surface water, domestic sewage and industrial wastewater. However, we found in experiments that ammonium ions are present in water samples

The colorimetric reaction in the isonicotinic acid-pyrazolone colorimetric method process can be seriously interfered, so that the absorbance value deviation is caused, the accuracy of a measuring result is seriously influenced, and the pollution degree of simple cyanide in the polluted water body is underestimated.

Disclosure of Invention

The invention aims to provide a solution for removing interference of ammonium ions on color reaction in a water sample cyanide content determination process, and aims to solve the problem that the absorbance value deviation influences the accuracy of a determination result due to the interference of the ammonium ions on the color reaction in the water sample cyanide content determination process by an isonicotinic acid-pyrazolone colorimetric method.

The invention also aims to provide a method for removing the interference of ammonium ions on the color reaction in the cyanide content determination process of a water sample.

The technical scheme adopted by the invention is that the solution for removing the interference of ammonium ions on the color reaction in the cyanide content determination process of the water sample is KH₂PO₄Solution, H₃BO₃Solution and NH₄And mixing the Cl solution to obtain a mixed solution, wherein the concentration of each component in the mixed solution is as follows: KH (Perkin Elmer)₂PO₄ 30～40mg/L、H₃BO₃ 0.10～0.15mg/L、NH₄Cl 100～150mg/L。

Further, the concentration of each component in the mixed solution is as follows: KH (Perkin Elmer)₂PO₄ 30mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 150mg/L。

The other technical scheme adopted by the invention is that the method for removing the interference of ammonium ions on the color reaction in the process of determining the cyanide content of the water sample is to determine CN in the water sample to be determined by adopting an isonicotinic acid-pyrazolone colorimetric method^-During content, in the process of obtaining a cyanide standard curve, adding the solution for removing the interference of ammonium ions on the color reaction in the process of determining the cyanide content of the water sample, and correcting the standard curve to ensure that CN in the water sample to be detected is determined by adopting the corrected standard curve^-The content is not interfered by ammonium ions.

Further, the specific steps of correcting the standard curve are as follows:

step S1, 6 25mL colorimetric tubes were taken, and 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL CN was added to each tube^-A standard potassium cyanide solution at 1mg/L was added followed by 0.5mL of Cyanide (CN) removed from the water sample^-) Adding a NaOH solution with the mass concentration of 0.1% to 10mL of a solution in which the ammonium ions interfere with the color reaction in the content determination process;

step S2, adding a phosphoric acid buffer solution with the pH value of 7.0 into the colorimetric tube obtained in the step S1, mixing uniformly, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering and shaking uniformly, and standing for 3-5 min;

step S3, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube in the step S2, fixing the volume to a marked line by using distilled water, shaking up, and then carrying out water bath for 40min at the temperature of 25-35 ℃;

and step S4, measuring the absorbance value of the solution after the water bath in the step S3 at the wavelength of 638nm, and drawing a cyanide standard curve.

Further, determining CN in the water sample to be detected through the corrected standard curve^-The content comprises the following steps:

step S21, adding 0.5-5.0 mL of water sample to be detected into a 25mL colorimetric tube, and then adding 0.1% NaOH solution to 10 mL;

step S22, adding a phosphoric acid buffer solution with the pH value of 7.0 into the colorimetric tube obtained in the step 1, uniformly mixing, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering, shaking up, and standing for 3-5 min;

step S23, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube in the step 2, fixing the volume to 25mL by using distilled water, shaking up, and then carrying out water bath at 25-35 ℃ for 40 min;

step S24, measuring the absorbance value of the solution after the water bath in the step 3 at the wavelength of 638nm, and calculating CN in the water sample according to a cyanide standard curve^-The concentration of (c).

Further, the phosphate buffer solution with a pH of 7.0 is prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate in distilled water, wherein the concentration of the potassium dihydrogen phosphate is 34g/L, and the concentration of the disodium hydrogen phosphate is 35.5 g/L.

Further, the isonicotinic acid-pyrazolone solution is a mixed solution obtained by uniformly mixing the pyrazolone solution with the isonicotinic acid solution before use; the isonicotinic acid solution is prepared by dissolving 1.5g of isonicotinic acid in 24mL of NaOH solution with the mass concentration of 2%, and adding distilled water to a constant volume of 100 mL; the pyrazolone solution is a solution obtained by dissolving 0.25g of pyrazolone in 20mL of dimethylformamide solution.

The method has the beneficial effects that the isonicotinic acid-pyrazolone colorimetric method is adopted to determine CN in the water sample to be detected^-When the content is higher, in the process of obtaining a cyanide standard curve, adding Cyanide (CN) for removing water sample^-) The solution of the interference of the ammonium ions to the color reaction in the content determination process can effectively remove the ammonium ions in the water sample

For simple Cyanide (CN)^-) The method has the advantages of accurate and reliable determination result, simple and convenient operation, practicality, quickness and strong operability, and solves the problem that the absorbance value deviation influences the accuracy of the determination result due to the interference of ammonium ions on the color development reaction in the process of determining the cyanide content of the water sample by adopting the isonicotinic acid-pyrazolone colorimetric method.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a graph of a standard curve 1 of cyanide concentration versus absorbance values for a water sample;

FIG. 2 is a graph of a standard curve 2 of cyanide concentration versus absorbance values for a water sample;

FIG. 3 is a graph of the corresponding standard curve when different volumes of solution A are added.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Removing ammonium ions

Simple Cyanide (CN) in water sample determined by isonicotinic acid-pyrazolone colorimetric method^-) The method for displaying reaction interference in the content process specifically comprises the following steps:

KCN standard curve 1:

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN (potassium cyanide) standard solution in which CN is in^-The concentration of the sodium hydroxide is 1mg/L, and then NaOH solution with the mass concentration of 0.1% is added to 10 mL;

step S2, adding 5mL of phosphoric acid buffer solution with the pH value of 7.0 into each colorimetric tube, mixing uniformly, quickly adding 0.2mL of chloramine T solution with the mass concentration of 1%, wherein the chloramine T solution is formed by dissolving 0.5g of chloramine T in water, diluting to 50mL, immediately covering, shaking uniformly, and standing for 3-5 min;

step S3, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube in the step 2, fixing the volume to 25mL by using distilled water, shaking up, and then carrying out water bath at 25-35 ℃ for 40 min;

at step S4, the absorbance value of the solution after the water bath of step S3 was measured at a wavelength of 638nm, and a KCN standard curve 1 as shown in FIG. 1 was plotted.

Sample measurement 1:

step 1, adding 0.5-5.0 mL of water sample to be detected into a 25mL colorimetric tube, wherein the amount of the water sample to be detected is determined according to CN in the water sample^-Is determined by the concentration of the water sample to be measured

The concentration of (B) is set to 50.0mg/L, which is in normal domestic sewage

The concentration of (a) is 20-30 mg/L, and the industrial wastewater contains

When the concentration of (b) is higher than 50.0mg/L, the water sample can be diluted into the water sample

Is treated with 50.0mg/L, and NaOH solution with the mass concentration of 0.1 percent is added to 10 mL;

step 2, adding 5mL of phosphoric acid buffer solution with the pH value of 7.0 into the colorimetric tube obtained in the step 1, uniformly mixing, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering and shaking up, and standing for 3-5 min;

step 3, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube obtained in the step 2, diluting to a constant volume of 25mL with distilled water, shaking up, and then carrying out water bath at 25-35 ℃ for 40 min;

step 4, measuring the absorbance value of the solution after the water bath in the step 3 at the wavelength of 638nm, and calculating simple Cyanide (CN) in the water sample according to a KCN standard curve 1 (figure 1)^-) The results of the measurement are shown in table 1:

TABLE 1 data of sample concentration results measured according to Standard Curve 1

Water sample preparation concentration (mg CN/L)	1.0	2.0	3.0
				Water sample fruitConcentration (mg CN/L) (SD)	0.78(0.02)	1.64(0.03)	2.38(0.02)

Example 2

KCN standard curve 2 (corrected):

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-Is 1mg/L, then 0.5mL of solution A is added, solution A is made up of KH₂PO₄Solution, H₃BO₃Solution and NH₄The Cl solution is mixed with the three solutions, and the concentrations of the three components in the mixed solution A are respectively 30mg/L KH₂PO₄、0.15mg/L H₃BO₃And 150mg/L NH₄Adding 0.1% NaOH solution to 10 mL;

step S2, adding a phosphoric acid buffer solution with the pH value of 7.0 into each colorimetric tube, mixing uniformly, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering, shaking uniformly, and standing for 3-5 min;

step S4, the absorbance value of the solution after the water bath of step S3 was measured at a wavelength of 638nm, and a KCN standard curve 2 as shown in FIG. 2 was plotted.

Sample measurement 2:

step 1, adding 0.5-5.0 mL of water sample to be detected (according to CN in the water sample) into a 25mL colorimetric tube^-Is determined by the concentration of the water sample to be measured

The concentration of (3) is 50.0mg/L), NaOH solution with the mass concentration of 0.1 percent is added to 10 mL;

step 2, adding a phosphoric acid buffer solution with the pH value of 7.0 into each colorimetric tube, uniformly mixing, quickly adding 0.2mL of chloramine T0.2 with the mass concentration of 1%, immediately covering, shaking up, and standing for 3-5 min;

step 4, measuring the absorbance value of the solution after the water bath in the step 3 at the wavelength of 638nm, and calculating simple Cyanide (CN) in the water sample according to the KNC standard curve 2^-) The results of the measurement are shown in Table 2.

Table 2 data of sample concentration results measured according to standard curve 2

Water sample preparation concentration (mg CN/L)	1.0	2.0	3.0
				Actually measured concentration of water sample (mg CN/L) (SD)	1.03(0.02)	2.18(0.05)	3.18(0.02)

Example 3

Selection of KCN standard curve:

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-The content of (1 mg/L) is added with 0.2, 0.5 and 1.0mL of solution A respectively, and then 0.1 percent of NaOH solution is added to 10 mL;

step S2, adding a phosphoric acid buffer solution with the pH value of 7.0 into the colorimetric tube obtained in the step 1, uniformly mixing, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering, shaking up, and standing for 3-5 min;

step S4, measuring the absorbance value of the solution after the water bath in the step 3 at the wavelength of 638nm to obtain different standard curves, and respectively calculating simple Cyanide (CN) in the water sample according to the different standard curves^-) The standard curve fitting equation of the addition of 0.2mL of solution A is y, as shown in FIG. 3₁The standard curve (corrected) fit equation with the addition of 0.5mL of solution A is y₂The standard curve fit equation for the addition of 1.0mL of solution A is y₃。

Method for calculating and determining simple Cyanide (CN) in water sample to be detected by using different standard curves^-) The results are shown in table 3:

TABLE 3 simple Cyanide (CN) in Water samples to be tested calculated from different standard curves^-) Concentration of (2)

Water sample preparation concentration (mg CN/L)	1.0	2.0	3.0
				Standard curve y₁Calculating the actually measured concentration (mg CN/L) (SD) of the water sample	0.83(0.02)	1.75(0.04)	2.54(0.02)
Standard curve y₂Calculating the actually measured concentration (mg CN/L) (SD) of the water sample	1.03(0.02)	2.18(0.05)	3.18(0.02)
				Standard curve y₃Calculating the actually measured concentration (mg CN/L) (SD) of the water sample	1.23(0.03)	2.60(0.05)	3.77(0.03)

A phosphate buffer solution with pH 7.0 was prepared by dissolving 3.40g of potassium dihydrogen phosphate and 3.55g of disodium hydrogen phosphate in 100mL of distilled water.

Dissolving 1.5g of isonicotinic acid in 24mL of NaOH solution with the mass concentration of 2%, and adding distilled water to a constant volume of 100mL to obtain isonicotinic acid solution; and dissolving 0.25g of pyrazolone in 20mL of dimethylformamide solution to obtain pyrazolone solution, and mixing the pyrazolone solution with 100mL of isonicotinic acid solution before use to obtain the isonicotinic acid-pyrazolone solution.

Example 4

Separately, potassium dihydrogen phosphate solutions of different concentrations were added:

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-The content of (A) is 1mg/L, and 0.5mL KH with different mass concentrations is respectively added into each colorimetric tube₂PO₄Adding NaOH solution with the mass concentration of 0.1% into the solution until the volume is 10 mL;

step S2, adding a phosphoric acid buffer solution with the pH value of 7.0 into the colorimetric tube in the step 1, mixing uniformly, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering, shaking uniformly, and standing for 3-5 min;

step S3, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube obtained in the step 2, diluting to a constant volume of 25mL with distilled water, shaking up, and then carrying out water bath at 25-35 ℃ for 40 min;

step S4, measuring the absorbance value of the solution after the water bath in the step S3 at the wavelength of 638nm, and adding KH with different concentrations₂PO₄Respectively calculating simple Cyanides (CN) in the water sample according to a standard curve obtained by the solution^-) The results are shown in Table 4. Adding 20mg/L KH₂PO₄Standard curve of the solution: 1.8969x, R²0.995; adding 30mg/L KH₂PO₄Standard curve of the solution: 1.7465x, R²0.9976; adding 50mg/L KH₂PO₄Standard curve of the solution: 1.8378x, R²＝0.9959。

TABLE 4 addition of KH alone₂PO₄CN in water sample to be detected calculated by standard curve obtained from solution^-Concentration of (2)

Example 5

Separately adding boric acid solutions of different concentrations:

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-The content of (A) is 1mg/L, and 0.5mL of H with different concentrations is respectively added into each nasal obstruction tube₃BO₃Adding NaOH solution with the mass concentration of 0.1% into the solution until the volume is 10 mL;

step S3, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube in the step S2, using distilled water to fix the volume to 25mL, shaking up, and then carrying out water bath at 25-35 ℃ for 40 min;

step S4, measuring the absorbance value of the solution after the water bath in the step S3 at the wavelength of 638nm, and adding H with different concentrations₃BO₃Respectively calculating simple Cyanides (CN) in the water sample according to a standard curve obtained by the solution^-) The results are shown in Table 5. Adding 0.07mg/L H₃BO₃Standard curve of the solution: 1.8248x (R)²0.9981), 0.15mg/L H was added₃BO₃Standard curve of the solution: y 1.781x, R²0.9981; adding 0.30mg/L H₃BO₃Standard curve of the solution: 1.7486x, R²＝0.9896。

TABLE 5 addition of H alone₃BO₃CN in water sample to be detected calculated by standard curve obtained from solution^-Concentration of (2)

Example 6

Separately, ammonium chloride solutions of different concentrations were added:

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-The content of (2) is 1mg/L, and 0.5mL of NH with different concentrations is respectively added into each colorimetric tube₄Adding a Cl solution, and then adding a NaOH solution with the mass concentration of 0.1% to 10 mL;

step S4, measuring the absorbance value of the solution after the water bath in the step S3 at the wavelength of 638nm, and adding NH with different concentrations₄Respectively calculating simple Cyanide (CN) in the water sample according to a standard curve obtained by using the Cl solution^-) The results are shown in Table 6. Adding 75mg/L NH₄Standard curve of Cl solution: 1.7927x, R²0.9979; adding 150mg/L NH₄Standard curve of Cl solution: 1.4686x, R²0.9944; adding 300mg/L NH₄Standard curve of Cl solution: 1.3706x, R²＝0.9929。

TABLE 6 addition of NH alone₄CN in water sample to be detected calculated by using standard curve obtained from Cl solution^-Concentration of (2)

Example 7

Add solutions a of different formulations:

step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-Is 1mg/L, and then 0.5mL of solutions A of different formulations (formulation 1: KH in the mixed solution A) are added to each cuvette respectively₂PO₄ 30mg/L、H₃BO₃0.15mg/L, formulation 2: mixing KH in the obtained solution A₂PO₄ 30mg/L、NH₄Cl 150mg/L, formulation 3: mixing H in the obtained solution A₃BO₃ 0.15mg/L、NH₄Cl 150mg/L, formulation 4: mixing KH in the obtained solution A₂PO₄ 30mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 150mg/L), and then adding NaOH solution with the mass concentration of 0.1% to 10 mL;

step S4, measuring the absorbance value of the solution after the water bath in the step S3 at the wavelength of 638nm, and respectively calculating simple Cyanide (CN) in the water sample according to a standard curve obtained by adding mixed solutions with different formulas^-) The results are shown in Table 7. Standard curve for addition of formulation 1 solution: 1.7741x (R)²0.999), add formula 2 solutionStandard curve of (2): 1.7964x (R)²0.9932), add standard curve for formulation 3 solution: 1.7868x (R)²0.9946), add standard curve for formulation 4 solution: 1.5344x (R)²＝0.9954)。

TABLE 7 CN in Water sample to be tested calculated from Standard curves obtained by adding solutions A of different formulations^-Concentration of (2)

As can be seen from the results of examples 4 to 7, the recipe was added in step S1: formulation 4 mixing KH in the obtained solution A₂PO₄ 30mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 150mg/L, simple Cyanide (CN) in water sample^-) The measured concentration is the closest to the prepared concentration, the interference effect of removing the ammonium ions on the reaction displayed in the process of measuring the cyanide content of the water sample is the best, and when other solutions A with various formulas are used, simple Cyanides (CN) in the water sample are measured in an actual way^-) The concentration of (a) is significantly lower.

Example 8

Step S1, taking 6 25mL colorimetric tubes, adding 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL KCN standard solutions respectively, and adding CN in the KCN standard solutions^-Is 1mg/L, and then 0.5mL of mixed solution of different formulations (formulation 1: KH in the mixed solution A) is added to each cuvette respectively₂PO₄ 35mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 150mg/L, formulation 2: mixing KH in the obtained solution A₂PO₄ 40mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 150mg/L, formulation 3: mixing KH in the obtained solution A₂PO₄30mg/L、H₃BO₃ 0.10mg/L、NH₄Cl 150mg/L, formulation 4: mixing KH in the obtained solution A₂PO₄ 30mg/L、H₃BO₃0.12mg/L、NH₄Cl 150mg/L, formulation 5: mixing KH in the obtained solution A₂PO₄ 30mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 100mg/L, formulation 6: mixing ofKH in the solution A₂PO₄ 30mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 130mg/L), and then adding NaOH solution with the mass concentration of 0.1% to 10 mL;

step S4, measuring the absorbance value of the solution after the water bath in the step S3 at the wavelength of 638nm, and respectively calculating simple Cyanide (CN) in the water sample according to a standard curve obtained by adding mixed solutions with different formulas^-) The results are shown in Table 8. Standard curve for addition of formulation 1 solution: 1.4397x (R)²0.9961), add standard curve of formulation 2 solution: 1.4487x (R)²0.9936), add standard curve for formulation 3 solution: 1.4657x (R)²0.9995), add standard curve of formulation 4 solution: 1.4634x (R)²0.9944), add standard curve for formulation 5 solution: 1.4503x (R)²0.9905), add standard curve for formulation 6 solution: 1.4578x (R)²＝0.9987)。

TABLE 8 CN in Water sample to be tested calculated from Standard Curve obtained by adding solution A^-Concentration of (2)

As can be seen from the results of the measurement in example 8, simple Cyanide (CN) was added to the water samples after 6 solutions A of different formulations were added in step S1^-) The measured concentration is closer to the prepared concentration, and the effect of removing the reaction interference displayed in the water sample cyanide content determination process by the ammonium ions is also ideal. Namely KH in the mixed solution A₂PO₄The concentration range of (A) is 30-40 mg/L, H₃BO₃The concentration range of (A) is 0.10-0.15 mg/L, NH₄The concentration range of Cl is 100-150 mg/L. However, the optimum formulation of the mixed solution a is: KH (Perkin Elmer)₂PO₄ 30mg/L、H₃BO₃ 0.15mg/L、NH₄Cl 150mg/L, simple Cyanide (CN) in water samples determined using this formulation^-) The measured concentration of (a) is closest to the formulated concentration.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. The method for removing the interference of ammonium ions on the color reaction in the process of determining the cyanide content of a water sample is characterized in that the method for determining CN in the water sample to be determined by adopting an isonicotinic acid-pyrazolone colorimetric method^-During content, in the process of obtaining a cyanide standard curve, adding a solution for removing interference of ammonium ions on a color reaction in the process of determining the cyanide content of the water sample, and correcting the standard curve to ensure that CN in the water sample to be detected is determined by adopting the corrected standard curve^-The content is not interfered by ammonium ions, and the solution for removing the interference of the ammonium ions on the color reaction in the cyanide content determination process of the water sample is formed by KH₂PO₄Solution, H₃BO₃Solution and NH₄And mixing the Cl solution to obtain a mixed solution, wherein the concentration of each component in the mixed solution is as follows: KH (Perkin Elmer)₂PO₄30~40mg/L、H₃BO₃0.10~0.15 mg/L、NH₄Cl 100~150 mg/L。

2. The method for removing the interference of ammonium ions on the color reaction in the cyanide content determination process of a water sample according to claim 1, wherein the calibration of the standard curve comprises the following steps:

step S1, 6 25mL colorimetric tubes were taken, and 0, 0.2, 0.5, 1.0, 2.0 and 3.0mL CN was added to each tube^-Standard potassium cyanide solution with concentration of 1mg/L, then 0.5mL is added to remove interference of ammonium ions on color reaction in the cyanide content determination process of the water sampleAdding NaOH solution with the mass concentration of 0.1% into the solution until the volume is 10 mL;

step S2, adding a phosphoric acid buffer solution with pH =7.0 into the colorimetric tube of the step S1, mixing uniformly, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering, shaking uniformly, and standing for 3-5 min;

3. The method for removing interference of ammonium ions on color reaction in cyanide content determination process of water sample according to claim 1, wherein the CN in the water sample to be detected is determined by using the corrected standard curve^-The content comprises the following steps:

step S22, adding a phosphoric acid buffer solution with pH =7.0 into the colorimetric tube of the step S21, mixing uniformly, quickly adding 0.2mL of chloramine T with the mass concentration of 1%, immediately covering, shaking uniformly, and standing for 3-5 min;

step S23, adding 5mL of isonicotinic acid-pyrazolone solution into the colorimetric tube in the step S22, fixing the volume to 25mL by using distilled water, shaking up, and then carrying out water bath at 25-35 ℃ for 40 min;

step S24, measuring the absorbance value of the solution after the water bath in the step S23 at the wavelength of 638nm, and calculating CN in the water sample according to a cyanide standard curve^-The concentration of (c).

4. The method for removing interference of ammonium ions on a color reaction in a cyanide content determination process of a water sample according to claim 2 or 3, wherein the phosphate buffer solution with pH =7.0 is prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate in distilled water, the concentration of the potassium dihydrogen phosphate is 34g/L, and the concentration of the disodium hydrogen phosphate is 35.5 g/L.

5. The method for removing the interference of ammonium ions on the color reaction in the cyanide content determination process of a water sample according to claim 2 or 3, wherein the isonicotinic acid-pyrazolone solution is a mixed solution obtained by uniformly mixing a pyrazolone solution with an isonicotinic acid solution before use;

the isonicotinic acid solution is prepared by dissolving 1.5g of isonicotinic acid in 24mL of NaOH solution with the mass concentration of 2%, and adding distilled water to a constant volume of 100 mL;

the pyrazolone solution is a solution obtained by dissolving 0.25g of pyrazolone in 20mL of dimethylformamide solution.