Method for detecting concentration of phosphite ions in natural water medium

Abstract

The invention provides a method for detecting the concentration of phosphite ions in a natural water medium, which comprises the following steps: detecting a to-be-detected sample solution containing phosphite ions and impurity ions by using an ion chromatograph to obtain a chromatogram of the to-be-detected sample; determining a peak area value of phosphite ions from the chromatogram of the sample to be detected; obtaining the concentration of the phosphite ions in the sample to be detected according to a linear regression equation of the peak area value of the phosphite ions and the concentration of the phosphite ions; wherein the test conditions of the ion chromatograph are as follows: an anion exchange column is selected as a chromatographic column, and the column temperature is 43-56 DEG C; the leacheate is a potassium hydroxide solution, the flow rate is 1.0-2.0 mL / min, gradient leaching is adopted, and the concentration of the leacheate is 15-18 mM within the time period of 0-14 min; the concentration of the leacheate is 33-36 mM within the time period of 16-30 min; the concentration of the leacheate is 17 to 20 mM within the time period of 32 to 36 minutes.

Description

Technical Field

[0001] The present invention belongs to the technical field of water sample analysis methods, and in particular relates to a method for detecting phosphite ion concentration in a natural water medium. Background Art

[0002] Phosphites have shown a wide range of application value in both agriculture and industry. In the agricultural field, phosphites, as plant growth regulators, can not only effectively control plant pathogens such as fungi and bacteria, but also promote the healthy growth of plants and improve the yield and quality of crops. In the industrial field, phosphites play multiple roles such as flame retardants, antioxidants or metal cleaning agents, showing their indispensable practical value. However, the environmental impact of phosphites cannot be ignored. High concentrations of phosphites are toxic to aquatic organisms and may cause serious damage to the ecosystem. Therefore, it is particularly important to monitor and manage the concentration of phosphites in the environment. This is not only a need to protect the ecosystem, but also an inevitable requirement for protecting human health.

[0003] In the detection of phosphite, traditional methods have certain limitations. For example, although the colorimetric method is easy to operate, it is easily interfered by factors such as sample color and turbidity due to the limitation of its detection principle, resulting in insufficient detection accuracy. Although ion chromatography has high accuracy, its application in natural water bodies faces many challenges. On the one hand, the coexisting ions in natural water bodies may interfere with the detection results; on the other hand, the peak time of ion chromatography is relatively late, which increases the time cost of the analysis process and is not conducive to rapid detection.

[0004] Therefore, there is still a need to improve the detection method so that the concentration of phosphite ions can be quickly and accurately detected when phosphite and other ions coexist, so as to meet the complex needs of phosphite ion detection in natural water bodies in practical applications. Summary of the invention

[0005] In view of this, the main purpose of the present disclosure is to provide a method for detecting the concentration of phosphite ions in natural water media, in order to at least partially solve at least one of the above-mentioned technical problems.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] In one aspect of the present disclosure, a method for detecting phosphite ion concentration in a natural water medium is provided, comprising:

[0008] An ion chromatograph is used to detect a sample solution containing phosphite ions and impurity ions to obtain a chromatogram of the sample to be tested; a peak area value of the phosphite ions is determined from the chromatogram of the sample to be tested; and the concentration of the phosphite ions in the sample to be tested is obtained according to a linear regression equation between the peak area value of the phosphite ions and the concentration of the phosphite ions.

[0009] Among them, the test conditions of the ion chromatograph are: the chromatographic column is an anion exchange column, the column temperature is 43~56℃; the eluent is potassium hydroxide solution, the flow rate is 1.0~2.0mL / min, and gradient elution is adopted: in the time period of 0-14min, the concentration of the eluent is 15~18mM; in the time period of 16-30min, the concentration of the eluent is 33mM~36mM; in the time period of 32-36min, the concentration of the eluent is 17mM~20mM.

[0010] According to an embodiment of the present disclosure, a method for detecting phosphite ions in a natural water medium is provided. When phosphite ions and other impurity ions are present in a sample to be tested, by jointly regulating the detection column temperature, eluent flow rate, eluent concentration, and injection volume of an ion chromatogram, while shortening the peak time, the separation between different ion peaks is effectively improved, thereby achieving rapid and accurate detection of phosphite ions. Phosphite ions are quantitatively calculated by an external standard method, thereby obtaining accurate phosphite ion concentration data. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The ion chromatogram is obtained by detecting a water body containing phosphite ions and various impurity ions using the test conditions of the ion chromatograph disclosed in the present invention;

[0012] Figure 2 It is the ion chromatogram of the phosphite standard solution with a concentration of 20 mg / L;

[0013] Figure 3 is a chromatogram of the natural water tested in Example 1 of the present disclosure;

[0014] Figure 4 is a chromatogram of the natural water body tested in Comparative Example 1 of the present disclosure;

[0015] Figure 5 is a chromatogram of the natural water body tested in Comparative Example 2 of the present disclosure;

[0016] Figure 6 is a chromatogram of the natural water body tested in Comparative Example 3 of the present disclosure;

[0017] Figure 7 is a chromatogram of the natural water body tested in Comparative Example 4 of the present disclosure;

[0018] Figure 8 is a chromatogram of the natural water body tested in Comparative Example 5 of the present disclosure;

[0019] Fig. 9 is a chromatogram of the natural water body tested in Comparative Example 6 of the present disclosure;

[0020] Fig.10 It is a chromatogram of the natural water tested in Comparative Example 7 of the present disclosure. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and drawings.

[0022] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this disclosure.

[0023] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0024] Phosphites are a class of compounds containing phosphite ions (PO 3 3- ) compounds. 4 3- ), phosphites have significant differences in chemical properties, in which the oxidation state of phosphorus atoms is usually +3, while the oxidation state of phosphorus atoms in phosphates is +5. Phosphites are widely present in a variety of environments and are widely used in agriculture and industry. In the process of realizing the concept of the present disclosure, it was found that in the detection of phosphites, although ion chromatography has a high accuracy, other impurity ions are usually present in natural water bodies, which will interfere with the determination of phosphite ions. Specifically, the chromatographic peaks overlap, resulting in the inability to accurately determine the ion concentration of phosphite. In addition, the peak time of phosphite ions is relatively late during ion chromatography detection, and it usually takes 20 to 30 minutes to peak, which increases the time cost of the analysis process and is not conducive to rapid detection. Therefore, how to ensure that phosphite ions are separated from interfering anions in water, while reducing the peak time and increasing the detection speed, and ensuring the detection of phosphite ions in natural water media has become the key to phosphite ion concentration detection.

[0025] The present disclosure finds that by adjusting the test conditions of the ion chromatograph and optimizing the column temperature, eluent flow rate, and eluent concentration, the peak time of the phosphite ion peak can be shortened, the separation between different ion peaks is effectively improved, and the detection of the phosphite ion concentration in the natural water medium is realized. The detection method disclosed in the present disclosure not only improves the sensitivity and accuracy of the detection, but also shortens the analysis time, so that the method can be more efficiently applied to the detection of actual samples, and provides technical support for the monitoring and management of phosphite concentration in the environment.

[0026] According to an embodiment of one aspect of the present disclosure, a method for detecting phosphite ion concentration in natural water is proposed, comprising:

[0027] An ion chromatograph is used to detect a sample solution containing phosphite ions and impurity ions to obtain a chromatogram of the sample to be tested; a peak area value of the phosphite ions is determined from the chromatogram of the sample to be tested; and the concentration of the phosphite ions in the sample to be tested is obtained according to a linear regression equation between the peak area value of the phosphite ions and the concentration of the phosphite ions.

[0028] Among them, the test conditions of the ion chromatograph are: the chromatographic column is an anion exchange column, the column temperature is 43~56℃; the eluent is potassium hydroxide solution, the flow rate is 1.0~2.0mL / min, and gradient elution is adopted: in the time period of 0~14min, the concentration of the eluent is 15~18mM; in the time period of 16-30min, the concentration of the eluent is 33~36mM; in the time period of 32~36min, the concentration of the eluent is 17~20mM.

[0029] The embodiments of the present disclosure provide a method for detecting phosphite ions in natural water media. When phosphite ions and other impurity ions are present in the sample to be tested, the test conditions such as the eluent concentration, flow rate, column temperature and injection volume in the ion chromatograph are adjusted. By jointly optimizing a variety of test conditions, the peak time of the phosphite ion is shortened, and the separation between it and other impurity ion peaks is improved, the peak overlap phenomenon is avoided, and the accuracy of the phosphite ion detection during the ion chromatography detection process is ensured. The accurate concentration of the phosphite ion in the sample to be tested is obtained by the linear regression equation of the phosphite ion concentration. By optimizing the test conditions, the rapid and accurate detection of the phosphite ion concentration in the natural water medium is achieved.

[0030] According to the embodiments of the present disclosure, the chromatographic column is an anion exchange column, for example, Dionex IonPacAS11-HC, 4 250mm, the stationary phase of the anion exchange column carries a positive charge, which can effectively attract and retain anions, such as phosphite ions, so that the anion exchange column can better separate and detect phosphite ions and reduce interference from other cations or neutral molecules.

[0031] The column temperature can be, for example, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C. Slight changes in column temperature can significantly affect peak time and peak shape. Appropriate column temperature can improve the separation of each ion peak in the sample, reduce peak time, and thus improve detection efficiency and accuracy. When implementing ion chromatography detection, phosphite ions can peak in about 10 to 14 minutes.

[0032] The eluent flow rate can be, for example, 1.0 mL / min, 1.2 mL / min, 1.4 mL / min, 1.6 mL / min, 1.8 mL / min, 2.0 mL / min, etc. The eluent flow rate can affect the separation effect and analysis time. A higher flow rate can shorten the analysis time, but may reduce the separation degree and damage the chromatographic column; a lower flow rate can improve the separation degree, but the analysis time will be correspondingly extended. Selecting a flow rate of 1.0~2.0 mL / min can simultaneously obtain a good separation effect and a reasonable analysis time, thereby improving the detection efficiency. Adopt gradient elution: in the time period of 0~14min, the concentration of the eluent is 15~18mM, for example, 15mM, 16mM, 17mM, 18mM, etc.; in the time period of 16~30min, the concentration of the eluent is 33~36mM, for example, 33mM, 34mM, 35mM, 36mM, etc.; in the time period of 32~36min, the concentration of the eluent is 17~20mM, for example, 17mM, 18mM, 19mM, 20mM, etc. Gradient elution can more effectively separate multiple ions in complex samples, and by gradually changing the concentration of the eluent, the peak overlap phenomenon is effectively avoided. If the concentration of the eluent is too high, the peak shape of the phosphite ion may become broadened or deformed, or even overlap with other ion peaks, affecting the separation effect and quantitative accuracy; if the concentration of the eluent is too low, the retention time of the phosphite ion may be too long, the analysis efficiency may be reduced, and all impurity ions may not be effectively separated, causing baseline interference.

[0033] According to the embodiment of the present disclosure, the guard column of the ion chromatograph is an anion guard column, which is used to intercept insoluble particles in the sample to be tested and adsorb impurities in the sample matrix, thereby reducing the degree of contamination of the chromatographic column. The specifications of the guard column match the chromatographic column, for example, Dionex lonPac AG11, 4 50mm guard column. The detection cell temperature is 30~40℃, for example, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, etc., preferably 35℃. Appropriate detection cell temperature can ensure the separation effect and detection sensitivity during ion chromatography detection, and also help reduce baseline drift and analysis errors caused by temperature fluctuations, thereby improving data accuracy and reliability.

[0034] According to the embodiments of the present disclosure, the detection mode of the ion chromatograph adopts electrochemical detection. Electrochemical detection can detect the current change generated when the electroactive molecules undergo oxidation or reduction reaction on the surface of the working electrode. It is suitable for detecting and analyzing ions with low dissociation degree, and can detect inorganic and organic ions at the μg / L level. Among them, the working electrode includes any one of a silver electrode, a platinum electrode, and a gold electrode, and the reference electrode includes any one of a silver / silver chloride electrode, a palladium hydrogen electrode, and a calomel electrode.

[0035] According to the embodiments of the present disclosure, the sample to be tested comes from at least one of natural water bodies, industrial wastewater, and domestic sewage. The present disclosure detects natural water bodies, various types of sewage, etc., and can detect the concentration of phosphite ions in water bodies where multiple impurity ions coexist. The impurity ions in the sample to be tested include at least one of nitrate ions, carbonate ions, bromide ions, nitrite ions, sulfate ions, chloride ions, and fluoride ions. In actual detection, for example, nitrate ions, carbonate ions, bromide ions, etc. are close to the peak time of phosphite ions, which are prone to interference during the detection process. The present disclosure adjusts the test conditions of the ion chromatograph to shorten the peak time while effectively improving the separation between different ion peaks, thereby achieving accurate detection of phosphite ion concentration.

[0036] According to the embodiments of the present disclosure, in actual operation, the test conditions of the ion chromatograph of the present disclosure can be used to perform ion chromatography detection on water bodies including nitrate ions, carbonate ions, bromide ions, nitrite ions, sulfate ions, phosphate ions, and chloride ions.

[0037] Figure 1 The ion chromatogram is obtained by detecting water containing phosphite ions and various impurity ions using the test conditions of the ion chromatograph disclosed in the present invention.

[0038] like Figure 1 As shown, by using the test conditions of the ion chromatograph of the present invention to perform ion chromatography detection on a water body containing phosphite ions and various impurity ions, the ion peaks of each ion can be clearly separated, and the phosphite ion can peak at about 12 to 13 minutes.

[0039] According to an embodiment of the present disclosure, before the sample to be tested is sampled and tested, the process also includes: centrifuging and filtering the sample to be tested. Since the sample to be tested in the present disclosure includes various types of sewage, etc., the sample to be tested needs to be centrifuged and filtered before testing to remove suspended matter, particulate matter and other impurities to avoid interference with the test results of the ion chromatograph, thereby ensuring the accuracy of the test data and the normal operation of the instrument.

[0040] According to an embodiment of the present disclosure, the linear regression equation of the peak area value of phosphite ions and the concentration of phosphite ions is obtained by the following steps: prepare standard solutions of phosphite ions of different concentrations, the concentration of phosphite ions in the standard solution is 0~50μg / L, for example, it can be 0μg / L, 10μg / L, 20μg / L, 30μg / L, 40μg / L, 50μg / L, etc., use an ion chromatograph to inject samples and detect respectively, and obtain a chromatogram of the standard solution; determine the peak area value of phosphite ions at different concentrations from the chromatogram of the standard solution; based on the concentration of phosphite ions in the standard solution and the peak area value of phosphite ions at different concentrations, construct a linear regression equation of the peak area value of phosphite ions and the concentration of phosphite ions. Among them, the test parameters for ion chromatography detection of standard solutions of phosphite ions of different concentrations are the same as the test parameters for detecting the sample solution to be tested containing phosphite ions and impurity ions disclosed in the present disclosure, and will not be repeated here.

[0041] According to an embodiment of the present disclosure, for example, an ion chromatograph may be used to sample and test a standard solution having a concentration of 20 mg / L to obtain a chromatogram of the standard solution. Figure 2 This is the ion chromatogram of a phosphite standard solution with a concentration of 20 mg / L. Figure 2 As shown, the peak area value of the phosphite ion can be determined from the chromatogram of the standard solution.

[0042] According to the embodiments of the present disclosure, in actual operation, a stock solution of a phosphite standard solution with a mass concentration of 1.0 μg / mL can be prepared and diluted to the following concentrations: 50 μg / L, 25 μg / L, 10 μg / L, 5 μg / L, 1 μg / L, and 0.5 μg / L to prepare standard solutions of phosphite ions with different concentrations.

[0043] According to the embodiments of the present disclosure, the phosphite ion concentration is calculated as shown in formula (1):

[0044] Formula (1).

[0045] Where A is the peak area value of the sample to be tested; A 0is the peak area value when the phosphate ion concentration is 0; a is the slope of the linear regression equation; b is the intercept of the linear regression equation.

[0046] First, the peak area value of the sample to be tested is subtracted from the peak area value when the phosphate ion concentration is 0, so as to perform baseline correction on the peak area value and eliminate the interference of non-specific signals. Then, the corrected peak area value is multiplied by the slope a of the linear regression equation to achieve a linear conversion of the peak area value to the phosphite ion concentration. Finally, the intercept b of the linear regression equation is subtracted to obtain the final phosphite ion concentration. Based on the established linear regression equation, the concentration of the phosphite ion can be quickly and accurately calculated through the peak area value of the sample to be tested.

[0047] By optimizing the test conditions of ion chromatography, such as selecting a suitable chromatographic column, column temperature, eluent flow rate, and using gradient elution techniques, the detection limit of phosphite ions can be reduced, thereby achieving accurate detection of phosphite ions in complex water bodies containing impurity ions such as natural water bodies or polluted water bodies.

[0048] In order to make the purpose, technical scheme and advantages of the present disclosure clearer, the present disclosure is further described in detail below in conjunction with specific examples and drawings. Specific techniques or conditions not specified in the examples are all conventional methods, which can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. It should be noted that the methods provided in the present disclosure are all conventional methods unless otherwise specified, and the reactants and reagents can be obtained from public commercial channels unless otherwise specified.

[0049] In the embodiment of the present invention, the required instruments include: an ion chromatograph Thermo ICS 2100+ equivalent instrument or above, and a 100,000th of a calorimeter equivalent instrument or above.

[0050] Embodiment 1:

[0051] In this embodiment 1, the concentration of phosphite ions in natural water samples is detected, specifically including:

[0052] Weigh the phosphite standard, dilute to volume with ultrapure water and shake well to obtain a 1 mg / L phosphite solution as a stock solution. Take 0.5 mL, 1 mL, 5 mL, 10 mL, 25 mL, and 50 mL of the stock solution and dilute to 1000 mL, filter with a 0.22 μm filter membrane, and obtain standard solutions of phosphite ions with different concentrations, which are 0.5 μg / L, 1 μg / L, 5 μg / L, 10 μg / L, 25 μg / L, and 50 μg / L, respectively.

[0053] The standard solutions of phosphite ions with different concentrations were injected with 500 μL of sample for detection by ion chromatography to obtain chromatograms of the standard solutions. The test conditions and parameters of the ion chromatography are shown in Table 1 below.

[0054] Table 1

[0055]

[0056] The peak area values ​​of phosphite ions at different concentrations were determined from the chromatogram of the standard solution. Based on the concentration of phosphite ions in the standard solution and the peak area values ​​of phosphite ions at different concentrations, a linear regression equation of the peak area value of phosphite ions and the concentration of phosphite ions was constructed. The results are shown in Table 2.

[0057] Table 2

[0058]

[0059] The regression equation is y = 516.04x-0.0334, where R 2 =0.9999. Phosphite ion has a good linear relationship with its peak area in the mass concentration range of 0.5~50μg / L.

[0060] The natural water body is tested by using an ion chromatograph (the test conditions of the ion chromatograph adopt the test conditions in Table 1) to obtain a chromatogram of the natural water body.

[0061] Figure 3 This is a chromatogram of the natural water tested in Example 1 of the present disclosure.

[0062] like Figure 3 As shown, the peak area value of the phosphite ion is determined to be 0.01 from the chromatogram. The concentration of the phosphite ion in the sample to be tested is calculated according to the linear regression equation between the peak area value of the phosphite ion and the phosphite ion concentration. The phosphite ion concentration is calculated as follows:

[0063]

[0064]

[0065] Comparative Example 1

[0066] This comparative example 1 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 3 below.

[0067] Table 3

[0068]

[0069] Figure 4 It is a chromatogram of the natural water tested in Comparative Example 1 of the present disclosure.

[0070] like Figure 4 As shown, the phosphite ion peak overlaps with the nitrate ion peak, and the separation degree from the bromide ion is poor, so the phosphite ion concentration cannot be accurately detected.

[0071] Comparative Example 2

[0072] This comparative example 2 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 4 below.

[0073] Table 4

[0074]

[0075] Figure 5 It is the chromatogram of the natural water tested in Comparative Example 2 of the present disclosure.

[0076] like Figure 5 As shown, the phosphite ion peak overlaps with the nitrate ion peak, and the separation degree from the bromide ion is poor, so the phosphite ion concentration cannot be accurately detected.

[0077] Comparative Example 3

[0078] This comparative example 3 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 5 below.

[0079] Table 5

[0080]

[0081] Figure 6 It is the chromatogram of the natural water tested in Comparative Example 3 of the present disclosure.

[0082] like Figure 6 As shown, the phosphite ion peak overlaps with the nitrate ion peak, and the separation degree from the bromide ion is poor, so the phosphite ion concentration cannot be accurately detected.

[0083] Comparative Example 4

[0084] This comparative example 4 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 6 below.

[0085] Table 6

[0086]

[0087] Figure 7It is a chromatogram of the natural water tested in Comparative Example 4 of the present disclosure.

[0088] like Figure 7 As shown, the phosphite ion peak appears later, at about 15 minutes.

[0089] Comparative Example 5

[0090] This comparative example 5 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 7 below.

[0091] Table 7

[0092]

[0093] Figure 8 It is the chromatogram of the natural water tested in Comparative Example 5 of the present disclosure.

[0094] like Figure 8 As shown, the phosphite ion peak appears later, at about 15 minutes.

[0095] Comparative Example 6

[0096] This comparative example 6 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 8 below.

[0097] Table 8

[0098]

[0099] Fig. 9 It is the chromatogram of the natural water tested in Comparative Example 6 of the present disclosure.

[0100] like Fig. 9 As shown, the separation between the phosphite ion peak and the nitrate ion peak is poor, and the phosphite ion concentration cannot be accurately detected.

[0101] Comparative Example 7

[0102] This comparative example 7 detects the phosphite ion concentration in the natural water sample. The difference from Example 1 is that the test conditions and parameters of the ion chromatograph are shown in Table 9 below.

[0103] Table 9

[0104]

[0105] Fig.10 It is a chromatogram of the natural water tested in Comparative Example 7 of the present disclosure.

[0106] like Fig.10As shown, the separation between the phosphite ion peak and the carbonate ion peak is poor, and the phosphite ion concentration cannot be accurately detected.

[0107] The present invention effectively improves the separation between different ion peaks while shortening the peak time by regulating the test conditions such as eluent concentration, flow rate, column temperature, and injection volume in the ion chromatograph, thereby realizing rapid and accurate detection of phosphite ions. By constructing a linear regression equation between the peak area value of phosphite ions and the phosphite ion concentration, the phosphite ion concentration data can be accurately calculated. The detection method disclosed in the present invention has good sensitivity, accuracy, and repeatability, and can be used to detect the phosphite ion concentration in natural water bodies.

[0108] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for detecting phosphite ion concentration in a natural water medium, characterized in that: The detection method comprises: Using an ion chromatograph to detect a sample solution containing phosphite ions and impurity ions to obtain a chromatogram of the sample; Determine the peak area value of the phosphite ion from the chromatogram of the sample to be tested; According to the linear regression equation of the peak area value of the phosphite ion and the phosphite ion concentration, the concentration of the phosphite ion in the sample to be tested is obtained; wherein the test conditions of the ion chromatograph are: The chromatographic column is an anion exchange column, and the column temperature is 43~56℃; The eluent was potassium hydroxide solution with a flow rate of 1.0~2.0mL / min, and gradient elution was adopted: in the time period of 0~14min, the concentration of the eluent was 15~18mM; in the time period of 16~30min, the concentration of the eluent was 33~36mM; in the time period of 32~36min, the concentration of the eluent was 17~20mM.

2. The detection method according to claim 1, characterized in that: The impurity ions include at least one of nitrate ions, carbonate ions, bromide ions, nitrite ions, sulfate ions, phosphate ions, chloride ions, and fluoride ions.

3. The detection method according to claim 1, characterized in that: The linear regression equation of the peak area value of the phosphite ion and the phosphite ion concentration is obtained by the following steps: Prepare standard solutions of phosphite ions with different concentrations, and use an ion chromatograph to perform sampling and detection respectively to obtain a chromatogram of the standard solution; Determine the peak area values ​​of the phosphite ion at different concentrations from the chromatogram of the standard solution; Based on the concentration of the phosphite ion in the standard solution and the peak area values ​​of the phosphite ion at different concentrations, a linear regression equation of the peak area value of the phosphite ion and the concentration of the phosphite ion is constructed.

4. The detection method according to claim 3, characterized in that: In the standard solution, the concentration of the phosphite ion is 0-50 μg / L.

5. The detection method according to claim 1, characterized in that: The phosphite ion concentration is calculated as shown in formula (1): Formula (1), in, A is the peak area value of the sample to be tested; A0 is the peak area value when the phosphate ion concentration is 0; a is the slope of the linear regression equation; b is the intercept of the linear regression equation.

6. The detection method according to claim 1, characterized in that: The sample to be tested comes from at least one of natural water, industrial wastewater and domestic sewage.

7. The detection method according to claim 1, characterized in that: The protective column of the ion chromatograph is an anion protective column, The detection cell temperature is 30~40℃.

8. The detection method according to claim 1, characterized in that: The detection mode of the ion chromatograph adopts electrochemical detection, wherein: The working electrode includes any one of a silver electrode, a platinum electrode, and a gold electrode. The reference electrode includes any one of a silver / silver chloride electrode, a palladium hydrogen electrode, and a calomel electrode.

9. The detection method according to claim 1, characterized in that: Before the sample to be tested is injected and tested, the method further comprises: The samples to be tested were centrifuged and filtered.

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