Method for testing content of perchlorate

Abstract

A method for testing the content of perchlorate comprises the following steps: adding a separating agent and an organic extractant I into a sample for extraction I, adding a fluorescent complexing agent solution into the obtained water phase, mixing, standing for more than 2 minutes, adding an organic extractant II for extraction II, and calculating the content of perchlorate in the sample according to the fluorescence characteristics of the obtained organic phase, the separating agent is prepared from crystals A, potassium chloride and water according to the mass ratio of (0.01-0.03): 1: (40-100); the main component of the crystal A is methylene blue; the fluorescent complexing agent is a phthalic acid bisamide derivative. The method is high in sensitivity and accurate in quantification; the capacity of resisting interference of inorganic anions is achieved, the sample pretreatment requirement is reduced, and the good detection effect on multiple kinds of liquid is achieved; the instrument hardware requirement is low, and the detection cost is low.

Description

Technical Field

[0001] The present invention relates to the field of physical and chemical analysis of chemical substances, and in particular to an analysis method for perchlorate. Background Art

[0002] Perchlorate (ClO4 - Perchlorate is an inorganic pollutant characterized by rapid diffusion, high stability, and resistance to degradation, leading to irreversible environmental pollution and damage to organisms. For example, even relatively low concentrations of perchlorate can interfere with the normal function of the thyroid gland, thereby affecting normal human metabolism and hindering normal growth and development. Therefore, rapid, sensitive, and accurate detection of perchlorate is of great significance to areas such as food safety, environmental protection, and public health.

[0003] Currently, the main methods for detecting perchlorate include: ion-selective electrode method, ion chromatography, ion chromatography-mass spectrometry, and liquid chromatography-mass spectrometry / mass spectrometry. However, these methods all have their own shortcomings: the ion-selective electrode method has general anti-interference ability, fast measurement speed, and relatively simple sample pretreatment. However, when the perchlorate concentration in the sample is lower than 50 μg / L, the measured results are less accurate, and inorganic anions such as nitrate and nitrite ions interfere severely, making it unreliable. Ion chromatography is an effective tool for analyzing anions and cations, but the detection cost is high and requires high professional qualifications from the operator. Ion chromatography-mass spectrometry is also expensive in terms of instrumentation and testing costs, and there is the problem of complex matrix suppression of electrospray signals, which performs poorly in the presence of complex matrices. When used for the analysis and detection of perchlorate, liquid chromatography-mass spectrometry / mass spectrometry often requires complex sample pretreatment (such as membrane filtration) to remove certain interfering substances, which increases the cost of analysis and testing and reduces efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for testing the perchlorate content with good accuracy and strong anti-interference ability.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: a method for testing perchlorate content, comprising adding a separating agent and an organic extractant I to a sample to perform extraction I, adding a fluorescent complexing agent solution to the resulting aqueous phase, mixing and allowing the mixture to stand for more than 2 minutes, then adding an organic extractant II to perform extraction II, and calculating the perchlorate content in the sample based on the fluorescence characteristics of the resulting organic phase;

[0006] The separating agent is prepared by mixing crystal A, soluble chloride and water in a mass ratio of 0.01-0.03:1:40-100;

[0007] The component of the crystal A is mainly methylene blue;

[0008] The fluorescent complexing agent is a phthalic acid bisamide derivative.

[0009] Preferably, the volume ratio of the sample to the separating agent is 10 to 50:1.

[0010] Preferably, the volume ratio of the separating agent to the organic extractant I is 1:0.8-1.2.

[0011] Preferably, the concentration of the fluorescent complexing agent solution is 1 wt% to 6 wt%; and the volume ratio of the aqueous phase to the fluorescent complexing agent solution is 10 to 50:1.

[0012] Preferably, the volume ratio of the fluorescent complexing agent solution to the organic extractant II is 1:0.8-1.2.

[0013] Preferably, the organic extractant I is one or more of chloroform, dichloromethane and dichloroethane.

[0014] Preferably, the organic extractant II is one or more of benzene, toluene and xylene.

[0015] Preferably, the separating agent is prepared by mixing crystal A, soluble chloride and water in a mass ratio of 0.015-0.025:1:50-90.

[0016] Preferably, the preparation method of the crystal A comprises: mixing methylene blue with water, adding soluble acetate, soluble carbonate and soluble bicarbonate under heating conditions, adjusting the pH value to 7.8-9, adding soluble chloride; and cooling to crystallize.

[0017] More preferably, the mass ratio of the methylene blue to water is 100:1200-1500.

[0018] More preferably, the mass ratio of the methylene blue to the soluble acetate is 100:8-12.

[0019] More preferably, the mass ratio of the methylene blue to the soluble carbonate is 100:8-12.

[0020] More preferably, the mass ratio of the methylene blue to the soluble bicarbonate is 100:0.4-0.8.

[0021] More preferably, the mass ratio of the methylene blue to the soluble chloride is 100:15-40.

[0022] More preferably, the heating temperature is 70-80°C.

[0023] More preferably, the crystallization temperature is greater than 0°C and less than or equal to 30°C.

[0024] More preferably, sodium hydroxide is used to adjust the pH.

[0025] Preferably, the fluorescent complexing agent is produced by reacting 1,3-ethylamino-p-cresol and phthalic anhydride in an inert atmosphere with a catalyst.

[0026] More preferably, the catalyst is zinc sulfate.

[0027] More preferably, the reaction solvent during the synthesis of the fluorescent complexing agent is chlorobenzene.

[0028] More preferably, the weight ratio of the 1,3-ethylamino-p-cresol to phthalic anhydride is 33-50:30-40.

[0029] More preferably, the weight ratio of the 1,3-ethylamino-p-cresol to the catalyst is 33-50:20-30.

[0030] More preferably, the reaction temperature during the synthesis of the fluorescent complexing agent is 190°C to 210°C.

[0031] More preferably, the reaction time for synthesizing the fluorescent complexing agent is 4 h to 6 h.

[0032] More preferably, the product obtained by the reaction is further purified by recrystallization using a methanol-chloroform mixed solution.

[0033] The present invention has the following beneficial effects:

[0034] (1) The method of the present invention has high sensitivity and accurate quantitative analysis;

[0035] (2) It has the ability to resist the interference of inorganic anions, reduces the need for sample pretreatment, and has better detection effect on complex samples;

[0036] (3) The instrument hardware requirements are low and the detection cost is low.

[0037] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 is the ultraviolet absorption spectrum of the fluorescent complexing agent of Example 1 of the present invention;

[0040] Figure 2This is the fluorescence emission spectrum obtained when the fluorescence intensity of the 0.1 mg / L group was tested in Example 1 of the present invention;

[0041] Figure 3 This is a working curve of the relationship between perchlorate concentration and fluorescence intensity in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, scheme and beneficial technology of the present invention clearer, the present invention is further described in detail below with reference to the embodiments and drawings. It should be noted that the embodiments described in this specification are only for explaining the present invention and are not intended to limit the present invention.

[0043] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0044] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and the "multiple" in "one or more" means two or more, and the "multiple" in "one or more" means two or more.

[0045] An embodiment of the present invention provides a method for testing perchlorate content, comprising adding a separating agent and an organic extractant I to a sample to perform extraction I, adding a fluorescent complexing agent solution to the resulting aqueous phase, mixing, and allowing the mixture to stand for more than 2 minutes, then adding an organic extractant II to perform extraction II, and calculating the perchlorate content in the sample based on the fluorescence characteristics of the resulting organic phase;

[0046] The separating agent is prepared by mixing crystal A, soluble chloride and water in a mass ratio of 0.01-0.03:1:40-100;

[0047] The component of the crystal A is mainly methylene blue;

[0048] The fluorescent complexing agent is a phthalic acid bisamide derivative.

[0049] The perchlorate content testing method of the present invention relies on a molecular fluorescence method. Perchlorate in a sample combines with an organically synthesized fluorescent complexing agent to form a fluorescent complex. The fluorescent complex can be extracted by an organic extractant II, and the fluorescence intensity generated after irradiation with light can realize quantitative analysis of the perchlorate in the sample, thereby establishing a highly sensitive, quantitatively accurate and reliable perchlorate content testing method. The perchlorate analysis method of the present invention has low requirements for instruments and equipment, low cost, and low requirements for sample pretreatment. It is suitable for the analysis of perchlorate in surface water, drinking water, wastewater, etc., and has strong versatility and high accuracy.

[0050] The examples show that the use of a separating agent also plays a key role in the quantitative accuracy of the method of the present invention. It also makes the method of the present invention have a strong anti-interference ability, especially the interference of inorganic anions, so that the method of the present invention can be applied to the detection of perchlorate in samples of different properties without the need for complex pretreatment, simplifying the test process and greatly improving the detection efficiency.

[0051] Before testing, a standard working curve of fluorescence intensity and perchlorate content can be calibrated using a standard solution and used for testing.

[0052] The testing method provided by the embodiment of the present invention has the following advantages:

[0053] (1) The method of the embodiment of the present invention has high sensitivity and accurate quantitative determination;

[0054] (2) It has the ability to resist the interference of inorganic anions, reduces the need for sample pretreatment, and has good detection effect on a variety of liquids;

[0055] (3) The instrument hardware requirements are low and the detection cost is low.

[0056] In some embodiments of the present invention, the crystals A contain, in addition to the main component methylene blue, soluble chloride. The separating agent contains soluble chloride, so a small amount of soluble chloride in the crystals A will not have much effect on the separating agent.

[0057] In an embodiment of the present invention, the volume ratio of the sample to the separating agent is 10 to 50:1.

[0058] In an embodiment of the present invention, the volume ratio of the separating agent to the organic extractant I is 1:0.8-1.2.

[0059] In an embodiment of the present invention, the concentration of the fluorescent complexing agent solution is 1 wt% to 6 wt%; and the volume ratio of the aqueous phase to the fluorescent complexing agent solution is 10 to 50:1.

[0060] In an embodiment of the present invention, the volume ratio of the fluorescent complexing agent solution to the organic extractant II is 1:0.8-1.2.

[0061] In an embodiment of the present invention, the organic extractant I is one or more of chloroform, dichloromethane, and dichloroethane.

[0062] In an embodiment of the present invention, the organic extractant II is one or more of benzene, toluene and xylene.

[0063] In an embodiment of the present invention, the separating agent is prepared by mixing crystal A, soluble chloride and water in a mass ratio of 0.015-0.025:1:50-90.

[0064] In an embodiment of the present invention, the method for preparing Crystals A comprises: mixing methylene blue with water, adding a soluble acetate, a soluble carbonate, and a soluble bicarbonate under heating conditions, adjusting the pH to 7.8-9, adding a soluble chloride, and cooling to crystallize. This preparation method has a certain purification effect, and the resulting Crystals A are primarily composed of methylene blue with a small amount of soluble chloride that does not affect analytical results, while avoiding the adverse effects of other impurities.

[0065] In some embodiments of the present invention, the mass ratio of methylene blue to water is 100:1200-1500.

[0066] In some embodiments of the present invention, the mass ratio of methylene blue to soluble acetate is 100:8-12.

[0067] In some embodiments of the present invention, the mass ratio of the methylene blue to the soluble carbonate is 100:8-12.

[0068] In some embodiments of the present invention, the mass ratio of the methylene blue to the soluble bicarbonate is 100:0.4-0.8.

[0069] In some embodiments of the present invention, the mass ratio of the methylene blue to the soluble chloride is 100:15-40.

[0070] In some embodiments of the present invention, the heating temperature is 70-80°C.

[0071] In some embodiments of the present invention, the crystallization temperature is greater than 0°C and less than or equal to 30°C.

[0072] In some embodiments of the present invention, sodium hydroxide is used to adjust the pH.

[0073] In an embodiment of the present invention, the fluorescent complexing agent is produced by reacting 1,3-ethylamino-p-cresol and phthalic anhydride in an inert atmosphere with a catalyst.

[0074] In some embodiments of the present invention, the catalyst is zinc sulfate.

[0075] In some embodiments of the present invention, the reaction solvent for synthesizing the fluorescent complexing agent is chlorobenzene.

[0076] In some embodiments of the present invention, the weight ratio of 1,3-ethylamino-p-cresol to phthalic anhydride is 33-50:30-40.

[0077] In some embodiments of the present invention, the weight ratio of the 1,3-ethylamino-p-cresol to the catalyst is 33-50:20-30.

[0078] In some embodiments of the present invention, the reaction temperature during the synthesis of the fluorescent complexing agent is 190°C to 210°C.

[0079] In some embodiments of the present invention, the reaction time for synthesizing the fluorescent complexing agent is 4 hours to 6 hours.

[0080] In some embodiments of the present invention, the product obtained by the reaction is further purified by recrystallization using a methanol-chloroform mixture.

[0081] In some embodiments of the present invention, the volume ratio of methanol to chloroform in the methanol-chloroform mixture is 1-3:1-3.

[0082] In some embodiments of the present invention, fluorescence characteristics are detected by exciting the fluorescence at 480 nm to 540 nm and measuring the fluorescence intensity at 560 nm to 610 nm. Within this range, the fluorescence intensity exhibits a good linear relationship with the perchlorate concentration, and since the fluorescence intensity lies within the visible light range, both fluorescence excitation and detection are relatively simple.

[0083] Example

[0084] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight. Unless otherwise stated, all reagents used in the examples are available through conventional commercial sources or synthesized according to conventional methods and can be used directly without further processing. Unless otherwise stated, all instruments used in the examples are available through conventional commercial sources.

[0085] Example 1

[0086] The separating agent in this example is Crystal A, potassium chloride, and water in a mass ratio of 0.03:1.5:100. Crystal A is prepared by adding 1500 ml of water to 100 g of methylene blue and heating to 70°C. Then, 10 g of sodium acetate, 10 g of sodium carbonate, and 0.6 g of sodium carbonate are slowly added. The pH is adjusted to 7.8 with sodium hydroxide, followed by the addition of 30 g of potassium chloride. The mixture is cooled to room temperature to precipitate shiny dark green crystals, which are then centrifuged and dried to obtain Crystal A. Crystal A is primarily composed of methylene blue, with a small amount of soluble chloride.

[0087] The fluorescent complexing agent in this example is a phthalic acid bisamide derivative. The preparation method for the fluorescent complexing agent in this example is as follows: 42.12 g of 1,3-ethylamino-p-cresol and 38.2 g of phthalic anhydride are weighed and dissolved in 250 mL of chlorobenzene. Then, 24.5 g of zinc sulfate is added, and the mixture is filled with argon. The reaction is carried out in a reaction vessel at 200°C for 5 hours, followed by cooling, filtration, and drying. The fluorescent complexing agent solid is then recrystallized from a methanol-chloroform (volume ratio 1:1) mixture. The solid powder is then dried at 50°C. Figure 1 It is the ultraviolet absorption spectrum of the obtained fluorescent complexing agent, and the ultraviolet absorption spectrum can be used to verify / judge that the synthesized product is the fluorescent complexing agent.

[0088] (1) Working curve calibration

[0089] A series of perchlorate solutions of known concentrations were prepared and treated with the method of the present invention to obtain the relationship between fluorescence characteristics and perchlorate content. The specific operation is as follows:

[0090] (1.1) Prepare six sets of aqueous perchlorate solutions at different concentrations: 0 mg / L, 0.02 mg / L, 0.04 mg / L, 0.06 mg / L, 0.08 mg / L, and 0.1 mg / L. Take 30 mL of each solution and place it in extraction vials. Add 1 mL of separating agent and 1 mL of organic extractant I (dichloroethane) to each extraction vial. Shake vigorously for 120 s, release the air, and let it rest for 300 s.

[0091] (1.2) Take 25 mL of the supernatant (aqueous phase) from each extraction bottle and transfer it to a colorimetric tube. Add 1 mL of a 5 wt% fluorescent complexing agent solution to each group and let it stand for 5 minutes. Add 1 mL of organic extractant II (toluene) to each colorimetric tube, shake vigorously for 20 seconds, and let it stand for 5 minutes. Discard the aqueous layer and retain the organic layer.

[0092] (1.3) Excite fluorescence at 510 nm, measure fluorescence intensity at 580 nm, and draw the equation of the fluorescence intensity vs. concentration curve.

[0093] Figure 2This is the fluorescence emission spectrum obtained when the fluorescence intensity of the 0.1 mg / L group was tested.

[0094] The relationship between the measured fluorescence intensity and the perchlorate content is shown in the following table:

[0095]

[0096] The regression equation obtained by least squares fitting is used as the standard working curve: F = kc + B, thereby obtaining the relationship between perchlorate concentration and fluorescence intensity; where k = 57051, B = 4265, c represents concentration, and F represents fluorescence intensity. The working curve is drawn as follows Figure 3 When the obtained working curve is used for testing, if the sample processing method is the same, the perchlorate concentration in the sample can be directly substituted into the formula. If the processing parameters are slightly different (such as the amount of organic extractant II used), a reasonably accurate result can also be obtained by proportional conversion.

[0097] (2) Take 0.050 mg / L perchlorate solution for testing

[0098] (2.1) Place 30 mL of a 0.050 mg / L perchlorate solution in an extraction flask. Add 1 mL of separating agent and 1 mL of organic extractant I (dichloroethane) to the flask. Shake vigorously for 120 s, release the air, and let it stand for 300 s.

[0099] (2.2) Transfer 25 mL of the supernatant (aqueous phase) from the extraction flask to a colorimetric tube; add 1 mL of a 5 wt% fluorescent complexing agent solution and let stand for 5 minutes; add 1 mL of organic extractant II (toluene) to the colorimetric tube, shake vigorously for 20 seconds, and let stand for 5 minutes; discard the aqueous layer and retain the organic layer;

[0100] (2.3) Excite fluorescence at 510 nm and measure fluorescence intensity at 580 nm. The relative intensity is 7134. Calculate the concentration based on the working curve and the result is 0.0503 mg / L.

[0101] Example 2

[0102] An unknown water sample was tested for perchlorate concentration, and the accuracy of the analysis was determined by spike recovery.

[0103] In this example, the spiked concentration was 0.035 mg / L. The spiked solution was prepared by pipetting 0.35 ml of a 10 mg / L perchlorate stock solution into a 100 mL volumetric flask. The solution was then brought to the mark with the water sample to be tested. The spiked recovery was calculated as: spiked recovery (%) = [(spike test value - water sample test value) / spiked concentration] * 100%.

[0104] The separating agent in this example is Crystal A, potassium chloride, and water in a mass ratio of 0.015:1:50. Crystal A is prepared by adding 1250 ml of water to 100 g of methylene blue and heating to 80°C. Then, 8 g of sodium acetate, 12 g of sodium carbonate, and 0.8 g of sodium carbonate are slowly added. The pH is adjusted to 8.5 with sodium hydroxide, followed by the addition of 40 g of potassium chloride. The mixture is cooled to room temperature to precipitate shiny dark green crystals, which are then centrifuged and dried to obtain Crystal A. Crystal A is primarily composed of methylene blue, with a small amount of soluble chloride.

[0105] The fluorescent complexing agent in this example is a phthalic acid bisamide derivative. The preparation method for the fluorescent complexing agent in this example is as follows: 35 g of 1,3-ethylamino-p-cresol and 40 g of phthalic anhydride are weighed and dissolved in 200 mL of chlorobenzene. 30 g of zinc sulfate is then added, and the mixture is filled with argon. The reaction is carried out in an autoclave at 210°C for 6 hours, followed by cooling, filtration, and drying. The solid fluorescent complexing agent is then recrystallized from a methanol-chloroform (volume ratio 2:1) solution and dried at 50°C.

[0106] The working curve used in this embodiment was obtained by testing a series of perchlorate aqueous solutions with known concentrations. Except for some different parameter values, the working curve calibration method is consistent with that of Example 1. The specific parameter selection is the same as the testing method of this embodiment.

[0107] The testing method of this embodiment is:

[0108] (1) Place 50 mL of the sample solution in an extraction flask, add 2 mL of separating agent and 2 mL of organic extractant I (dichloromethane) to the extraction flask; shake vigorously for 120 s, release the air, and let it stand for 300 s;

[0109] (2) Take 30 mL of the supernatant (aqueous phase) from the extraction flask and transfer it to a colorimetric tube; add 2 mL of a fluorescent complexing agent solution (2 wt%) and let it stand for 5 min; add 2 mL of organic extractant II (benzene) to the colorimetric tube, shake vigorously for 20 s, and let it stand for 5 min; discard the aqueous layer and retain the organic layer;

[0110] (3) Excite fluorescence at 510 nm, measure the fluorescence intensity at 580 nm, and calculate the perchlorate concentration based on the working curve.

[0111] In this example, the spiked concentration was 0.035 mg / L. The final perchlorate concentration in the unknown water sample was measured to be 0.035 mg / L, and the spiked test value was 0.068 mg / L. The spiked recovery rate was 94.3%, indicating that the test results were relatively accurate.

[0112] Comparative Example 1

[0113] An unknown water sample was tested for perchlorate concentration, and the accuracy of the analysis result was determined by spike recovery. The test method of this comparative example was essentially the same as that of Example 2, except that no separation agent was used (water was used instead).

[0114] For this comparative example, the spike concentration was 0.1 mg / L. The spike solution was prepared by pipetting 0.1 mL of a 100 mg / L perchlorate stock solution into a 100 mL volumetric flask. The solution was then brought to the mark with the water sample to be tested. The spike recovery was calculated as: Spiked recovery (%) = [(Spike test value - Water sample test value) / Spiked concentration] * 100%.

[0115] The test method of this comparative example is:

[0116] (1) Take 50 mL of the sample solution and place it in an extraction bottle. Add 2 mL of water and 2 mL of organic extractant I (dichloromethane) to the extraction bottle; shake vigorously for 120 seconds, release the gas, and let it stand for 300 seconds;

[0117] (2) Take 30 mL of the supernatant (aqueous phase) from the extraction flask and transfer it to a colorimetric tube; add 2 mL of a fluorescent complexing agent solution (2 wt%) and let it stand for 5 min; add 2 mL of organic extractant II (benzene) to the colorimetric tube, shake vigorously for 20 s, and let it stand for 5 min; discard the aqueous layer and retain the organic layer;

[0118] (3) Excite fluorescence at 510 nm, measure the fluorescence intensity at 580 nm, and calculate the perchlorate concentration based on the working curve.

[0119] The fluorescent complexing agent in this comparative example is the same as that in Example 2.

[0120] The working curve used in this comparative example was obtained by testing a series of perchlorate aqueous solutions with known concentrations, and the testing method was the same as the testing method for the unknown samples to be tested in this comparative example.

[0121] The spiked concentration in this comparative example was 0.1 mg / L. The final measured perchlorate concentration in the unknown water sample was 0.098 mg / L, and the spiked test value was 0.257 mg / L; the spiked recovery rate was 160%. The test results have a large deviation.

[0122] Comparative Example 2

[0123] An unknown water sample was tested for perchlorate concentration, and the accuracy of the analysis result was determined by spike recovery. The test method of this comparative example was substantially the same as that of Example 2, except that no fluorescent complexing agent solution was used (water was used instead).

[0124] In this example, the spiked concentration was 0.035 mg / L. The spiked solution was prepared by pipetting 0.35 ml of a 10 mg / L perchlorate stock solution into a 100 mL volumetric flask. The solution was then brought to the mark with the water sample to be tested. The spiked recovery was calculated as: spiked recovery (%) = [(spike test value - water sample test value) / spiked concentration] * 100%.

[0125] The test method of this comparative example is:

[0126] (1) Place 50 mL of the sample solution in an extraction flask, add 2 mL of separating agent and 2 mL of organic extractant I (dichloromethane) to the extraction flask; shake vigorously for 120 s, release the air, and let it stand for 300 s;

[0127] (2) Take 30 mL of the supernatant (aqueous phase) from the extraction flask and transfer it to a colorimetric tube; add 2 mL of water and let it stand for 5 minutes; add 2 mL of organic extractant II (benzene) to the colorimetric tube, shake vigorously for 20 seconds, and let it stand for 5 minutes; discard the aqueous layer and retain the organic layer;

[0128] (3) Excite fluorescence at 510 nm, measure the fluorescence intensity at 580 nm, and calculate the perchlorate concentration based on the working curve.

[0129] The separating agent in this comparative example is the same as that in Example 2.

[0130] Since no fluorescent complexing agent was used in this comparative example, the fluorescence intensity did not change substantially with the perchlorate concentration, and a working curve could not be obtained. Therefore, the working curve of Example 2 was used for calculation as the detection result.

[0131] The spiked concentration in this comparative example was 0.035 mg / L. The final measured perchlorate concentration in the unknown water sample was 0.003 mg / L, and the spiked test value was 0.002 mg / L. The spiked test value was even lower than the unspiked value, making this comparative example's method completely unworkable.

[0132] Example 3

[0133] An unknown water sample was tested for perchlorate concentration, and the accuracy of the analysis results was determined by spike recovery. To test the ability of the separating agent in the method of the present invention to resist ion interference, 10 mg / L nitrate and 2 mg / L chlorate were added to the unknown water sample in this example.

[0134] In this example, the spiked concentration was 0.035 mg / L. The spiked solution was prepared by pipetting 0.35 ml of a 10 mg / L perchlorate stock solution into a 100 mL volumetric flask. The solution was then brought to the mark with the water sample to be tested. The spiked recovery was calculated as: spiked recovery (%) = [(spike test value - water sample test value) / spiked concentration] * 100%.

[0135] The separating agent in this example is Crystal A, potassium chloride, and water in a mass ratio of 0.025:1:80. Crystal A is prepared by adding 1200 ml of water to 100 g of methylene blue and heating to 75°C. Then, 12 g of sodium acetate, 8 g of sodium carbonate, and 0.4 g of sodium carbonate are slowly added. The pH is adjusted to 9 with sodium hydroxide, followed by the addition of 15 g of potassium chloride. The mixture is cooled to room temperature to precipitate shiny dark green crystals, which are then centrifuged and dried to obtain Crystal A. Crystal A is primarily composed of methylene blue, with a small amount of soluble chloride.

[0136] The fluorescent complexing agent in this example is a phthalic acid bisamide derivative. The preparation method for the fluorescent complexing agent in this example is as follows: 45 g of 1,3-ethylamino-p-cresol and 30 g of phthalic anhydride are weighed and dissolved in 400 mL of chlorobenzene. Then, 20 g of zinc sulfate is added, and the mixture is filled with argon. The reaction is carried out in an autoclave at 190°C for 4 hours, followed by cooling, filtration, and drying. The solid fluorescent complexing agent is then recrystallized from a methanol-chloroform (volume ratio 1:2) solution and dried at 50°C.

[0137] The working curve used in this embodiment was obtained by testing a series of perchlorate aqueous solutions with known concentrations. Except for some different parameter values, the working curve calibration method is consistent with that of Example 1. The specific parameter selection is the same as the testing method of this embodiment.

[0138] The testing method of this embodiment is:

[0139] (1) Place 10 mL of the sample solution in an extraction flask, add 1 mL of separating agent and 1 mL of organic extractant I (chloroform) to the flask; shake vigorously for 120 s, release the air, and let it stand for 300 s;

[0140] (2) Take 5 mL of the supernatant (aqueous phase) from the extraction flask and transfer it to a colorimetric tube; add 0.5 mL of a fluorescent complexing agent solution (6 wt%) and let it stand for 5 min; add 0.4 mL of organic extractant II (xylene) to the colorimetric tube, shake vigorously for 20 s, and let it stand for 5 min; discard the aqueous layer and retain the organic layer;

[0141] (3) Excite fluorescence at 510 nm, measure the fluorescence intensity at 580 nm, and calculate the perchlorate concentration based on the working curve.

[0142] In this example, the spiked concentration was 0.035 mg / L. The final perchlorate concentration in the unknown water sample was measured to be 0.036 mg / L, and the spiked test value was 0.070 mg / L. The spiked recovery rate was 97.2%, indicating that the test results were relatively accurate.

[0143] Comparative Example 3

[0144] An unknown water sample was tested for perchlorate concentration, and the accuracy of the analysis results was determined by spike recovery. To verify the ability of the separating agent in the present method to resist ion interference, 10 mg / L nitrate and 2 mg / L chlorate were added to the unknown water sample in this comparative example. The testing method of this comparative example is essentially the same as that of Example 3, except that no separating agent was used (water was used instead).

[0145] For this comparative example, the spike concentration was 0.2 mg / L. The spike solution was prepared by pipetting 0.2 mL of a 100 mg / L perchlorate stock solution into a 100 mL volumetric flask. The solution was then brought to the mark with the water sample to be tested. The spike recovery was calculated as: Spiked recovery (%) = [(Spike test value - Water sample test value) / Spiked concentration] * 100%.

[0146] The test method of this comparative example is:

[0147] (1) Place 10 mL of the sample solution in an extraction flask, add 1 mL of water and 1 mL of organic extractant I (chloroform) to the flask; shake vigorously for 120 s, release the air, and let it stand for 300 s;

[0148] (2) Take 5 mL of the supernatant (aqueous phase) from the extraction flask and transfer it to a colorimetric tube; add 0.5 mL of a fluorescent complexing agent solution (6 wt%) and let it stand for 5 min; add 0.4 mL of organic extractant II (xylene) to the colorimetric tube, shake vigorously for 20 s, and let it stand for 5 min; discard the aqueous layer and retain the organic layer;

[0149] (3) Excite fluorescence at 510 nm, measure the fluorescence intensity at 580 nm, and calculate the perchlorate concentration based on the working curve.

[0150] The fluorescent complexing agent in this comparative example is the same as that in Example 3.

[0151] The working curve used in this comparative example was obtained by testing a series of perchlorate aqueous solutions with known concentrations, and the testing method was the same as the testing method for the unknown samples to be tested in this comparative example.

[0152] The spiked concentration in this comparative example was 0.2 mg / L. The final measured perchlorate concentration in the unknown water sample was 0.254 mg / L, and the spiked test value was 0.687 mg / L; the spiked recovery rate was 192%. The test results have a large deviation.

Claims

1. A method for testing perchlorate content, characterized in that: A separating agent and an organic extractant I are added to the sample to perform extraction I, a fluorescent complexing agent solution is added to the resulting aqueous phase, the mixture is mixed and allowed to stand for more than 2 minutes, and then an organic extractant II is added to perform extraction II. The perchlorate content in the sample is calculated based on the fluorescence characteristics of the resulting organic phase; The separating agent is prepared by mixing crystal A, soluble chloride and water in a mass ratio of 0.01-0.03:1:40-100; The component of the crystal A is mainly methylene blue; The fluorescent complexing agent is a phthalic acid bisamide derivative.

2. The method for testing perchlorate content according to claim 1, wherein: The volume ratio of the sample to the separating agent is 10-50:1; the volume ratio of the separating agent to the organic extractant I is 1:0.8-1.

2.

3. The method for testing perchlorate content according to claim 1, wherein: The concentration of the fluorescent complexing agent solution is 1wt% to 6wt%; the volume ratio of the aqueous phase to the fluorescent complexing agent solution is 10 to 50:1; and the volume ratio of the fluorescent complexing agent solution to the organic extractant II is 1:0.8 to 1.

2.

4. The method for testing perchlorate content according to any one of claims 1 to 3, characterized in that: The organic extractant I is one or more of chloroform, dichloromethane, and dichloroethane; the organic extractant II is one or more of benzene, toluene, and xylene.

5. The method for testing perchlorate content according to claim 1 or 2, characterized in that: The separating agent is prepared by mixing crystal A, soluble chloride and water in a mass ratio of 0.015-0.025:1:50-90.

6. The method for testing perchlorate content according to claim 1, wherein: The preparation method of the crystal A comprises: mixing methylene blue with water, adding soluble acetate, soluble carbonate and soluble bicarbonate under heating conditions, adjusting the pH value to 7.8-9, adding soluble chloride; and cooling to crystallize.

7. The method for testing perchlorate content according to claim 6, wherein: The mass ratio of the methylene blue to water is 100:1200-1500; the mass ratio of the methylene blue to soluble acetate is 100:8-12; the mass ratio of the methylene blue to soluble carbonate is 100:8-12; the mass ratio of the methylene blue to soluble bicarbonate is 100:0.4-0.8; and the mass ratio of the methylene blue to soluble chloride is 100:15-40.

8. The method for testing perchlorate content according to claim 6 or 7, characterized in that: The heating temperature is 70-80° C.; the crystallization temperature is greater than 0° C. and less than or equal to 30° C.; and sodium hydroxide is used to adjust the pH value.

9. The method for testing perchlorate content according to any one of claims 1 to 3, characterized in that: The fluorescent complexing agent is generated by reacting 1,3-ethylamino-p-cresol and phthalic anhydride in an inert atmosphere with a catalyst.

10. The method for testing perchlorate content according to claim 9, characterized in that: The catalyst is zinc sulfate; the reaction solvent is chlorobenzene; the weight ratio of 1,3-ethylamino-p-cresol to phthalic anhydride is 33-50:30-40; the weight ratio of 1,3-ethylamino-p-cresol to the catalyst is 33-50:20-30; the reaction temperature is 190° C. to 210° C.; the reaction time is 4 h to 6 h; and the product obtained by the reaction is purified by recrystallization using a methanol-chloroform mixture.

Images