Iron ion detection fluorescent probe, application and fluorescence detection method

Abstract

The invention relates to an iron ion detection fluorescent probe, application and a fluorescence detection method, belongs to the technical field of iron content detection, and solves the technical problems of tedious operation, time consumption and the like in the detection of the iron content in magnesium oxide. The preparation method of the fluorescent probe comprises the following steps: step 1, weighing pyrazine-2, 3, 5, 6-tetracarboxylic acid and Zn (NO) 3, dissolving the pyrazine-2, 3, 5, 6-tetracarboxylic acid and Zn (NO) 3 in a mixed solvent of N, N-dimethylformamide and dimethyl sulfoxide, and stirring to obtain a mixed solution; and step 2, continuously heating the mixed solution obtained in the step 1 in a drying oven to obtain a white transparent blocky crystal, and washing, filtering, drying and grinding the white transparent blocky crystal to obtain the fluorescent probe. A novel zinc-based compound is synthesized through a solvothermal method and serves as a fluorescent probe to be used for fluorescence detection of iron ions in magnesium oxide, trace detection of the iron ions can be achieved, and therefore low-magnetism magnesium oxide with the iron content meeting the industrial standard requirement is screened out.

Description

Technical Field

[0001] The present invention belongs to the technical field of iron content detection, and specifically relates to a fluorescent probe for iron ion detection, its application and a fluorescence detection method. Background Art

[0002] Magnesium oxide, also known as magnesia, is a white hygroscopic solid mineral that exists in nature in the form of periclase and is a raw material for smelting magnesium (or oxides). As a refractory material, magnesium oxide has physical and chemical stability at high temperatures; as a building material, it has excellent properties such as fire prevention, termite prevention, moisture resistance, mildew resistance and high strength; as an antacid, magnesium supplement and short-term laxative, it can also be used in the medical field to relieve heartburn and indigestion. With the improvement of the purity of magnesium oxide, its application performance will also be improved, so it is necessary to monitor the impurity content in high-purity magnesium oxide.

[0003] The impurity content of high-purity magnesium oxide needs to be strictly controlled. According to different customer requirements, calcium, iron, silicon, aluminum and heavy metals need to meet specific standards to ensure the quality and performance of the product. Among them, iron is a common impurity in magnesium oxide, and its content is clearly required in the industry standard. For example, HG / T-6066-2022 stipulates that the iron ion in magnesium oxide for mineral insulated cables should be less than or equal to 0.5%.

[0004] The common conventional detection method for iron ions usually follows the chemical analysis method of magnesium-aluminum refractory materials in GB / T5069-2015: orthophenanthroline spectrophotometry. Its principle is to melt with a mixed flux of sodium carbonate-boric acid and leach with dilute hydrochloric acid. Hydroxylamine hydrochloride is used to reduce Fe(III) to Fe(II). In a weakly acidic solution, Fe(II) forms an orange-red complex with orthophenanthroline, and its absorbance is measured at a wavelength of 510 nm with a spectrophotometer. The advantage of this method is accuracy, but there are also some disadvantages that are not conducive to enterprise application, such as complex operation, long time consumption, and complicated required reagents.

[0005] Therefore, it is urgently necessary to develop a method for quickly detecting the iron impurity content that meets the magnesium oxide industry standard. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art, and provide a fluorescent probe for iron ion detection, its application and a fluorescence detection method, which solve the technical problems such as cumbersome operation and time consumption in the detection of iron content in magnesium oxide.

[0007] To solve the above problems, the technical solution of the present invention is: a fluorescent probe for iron ion detection, and the molecular formula of the fluorescent probe is (Zn2(C8O8N2H2)·DMSO·HCOOH) n .

[0008] Preferably, the preparation steps of the fluorescent probe are as follows:

[0009] Step 1: Weigh pyrazine-2,3,5,6-tetracarboxylic acid and Zn(NO)3 and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). After stirring, a mixed solution is obtained; the mass ratio of pyrazine-2,3,5,6-tetracarboxylic acid to Zn(NO)3 is 1:6, and the volume ratio of N,N-dimethylformamide (DMF) to dimethyl sulfoxide (DMSO) is 3:1.

[0010] Step 2: Place the mixed solution obtained in Step 1 in an oven at 90°C ± 5°C and continuously heat it for 4 to 6 days to obtain white transparent block crystals. After washing, filtering, drying, and grinding the white transparent block crystals, the fluorescent probe is obtained.

[0011] Preferably, the stirring time in Step 1 is 30 min - 60 min.

[0012] Another object of the present invention is to provide an application of the above-mentioned iron ion detection fluorescent probe in the rapid detection of iron content in magnesium oxide.

[0013] Another object of the present invention is to provide a fluorescent detection method for rapidly detecting the iron content in magnesium oxide, including the following steps:

[0014] Step 1: Weigh 0.5 g of dried magnesium oxide into a platinum crucible. Add 4.0 g of anhydrous sodium carbonate and 2.7 g of boric acid to the platinum crucible and mix evenly. Cover the platinum lid and leave a slight gap. Place it in a high-temperature furnace. First, heat it slowly, and then gradually increase the temperature to 1100°C ± 25°C and heat for 10 min. Take out the crucible and cover it with a platinum lid or a watch glass; after the crucible cools slightly, add 55 mL of sulfuric acid solution while stirring and heat it in a steam bath until the sample is completely dissolved. After cooling, transfer it to a volumetric flask and make up the volume to obtain a magnesium oxide solution.

[0015] Step 2: Take 1 mg of the above-mentioned iron ion detection fluorescent probe, add 3 mL of the magnesium oxide solution prepared in Step 1 to it, mix evenly, and measure the fluorescence intensity of the iron ion detection fluorescent probe at an excitation wavelength of 290 nm.

[0016] Preferably, in Step 2, the volume ratio of sulfuric acid to water in the sulfuric acid solution is 1:9.

[0017] Compared with the prior art, the beneficial effects of the present invention:

[0018] The fluorescence detection method of the present invention uses pyrazine-2,3,5,6-tetracarboxylic acid as a ligand, and a novel zinc-based compound is synthesized by a solvothermal method. As a fluorescence probe, it is used for the fluorescence detection of iron ions in magnesium oxide, enabling the micro-detection of iron ions, thereby screening out low-magnetic magnesium oxide with iron content meeting the requirements of industry standards. Using the method of the present invention to determine the iron content in industrial magnesium oxide has the characteristics of rapid response, high selectivity, high sensitivity, and low price. Compared with the existing iron ion detection technologies, this fluorescence detection technology has the advantages of low cost, high sensitivity, and convenient operation, and has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the structure of the pyrazine-2,3,5,6-tetracarboxylic acid ligand;

[0020] Figure 2 is the coordination environment diagram of the fluorescence probe for iron ion detection;

[0021] Figure 3 is the two-dimensional structure diagram of the fluorescence probe for iron ion detection;

[0022] Figure 4 is the powder X-ray diffraction pattern of the fluorescence probe for iron ion detection;

[0023] Figure 5 is the infrared spectrum of the fluorescence probe for iron ion detection;

[0024] Figure 6 is the detection diagram of the fluorescence probe for iron ion detection against metal ions;

[0025] Figure 7 is for different Fe 3+ fluorescence change diagram at concentrations;

[0026] Figure 8 is the Stern-Volmer (SV) equation;

[0027] Figure 9 is the bar graph of the anti-interference experiment in different solutions. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0029] Example 1: This example provides a fluorescence probe for iron ion detection, and the molecular formula of the fluorescence probe is (Zn2(C8O8N2H2)·DMSO·HCOOH) n .

[0030] The preparation steps of the fluorescence probe for iron ion detection are as follows:

[0031] Step 1: Weigh pyrazine-2,3,5,6-tetracarboxylic acid and Zn(NO)3 and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). After stirring for 30 min - 60 min, a mixed solution is obtained; the mass ratio of pyrazine-2,3,5,6-tetracarboxylic acid to Zn(NO)3 is 1:6, and the volume ratio of N,N-dimethylformamide (DMF) to dimethyl sulfoxide (DMSO) is 3:1;

[0032] Step 2: Place the mixed solution obtained in Step 1 in an oven at 90°C ± 5°C and continuously heat it for 4 days - 6 days to obtain white transparent block crystals. After washing, filtering, drying, and grinding the white transparent block crystals, an iron ion detection fluorescent probe is obtained.

[0033] Example 2: This example provides an application of the iron ion detection fluorescent probe in Example 1 for rapidly detecting the iron content in magnesium oxide.

[0034] Example 3: This example provides a fluorescent detection method for rapidly detecting the iron content in magnesium oxide, including the following steps:

[0035] Step 1: Weigh 0.5 g of dried magnesium oxide into a platinum crucible. Add 4.0 g of anhydrous sodium carbonate and 2.7 g of boric acid to the platinum crucible and mix evenly. Cover the platinum crucible and leave a slight gap. Place it in a high-temperature furnace. First, heat it slowly, and then gradually increase the temperature to 1100°C ± 25°C and heat for 10 min. Take out the crucible and cover it with a platinum lid or a watch glass; after the crucible cools slightly, add 55 mL of sulfuric acid solution while stirring. The volume ratio of sulfuric acid to water in the sulfuric acid solution is 1:9. Heat it in a steam bath until the sample is completely dissolved. After cooling, transfer it to a volumetric flask and make up the volume to obtain a magnesium oxide solution;

[0036] Step 2: Take 1 mg of the iron ion detection fluorescent probe in Example 1, add 3 mL of the magnesium oxide solution prepared in Step 1 to it, mix evenly, and measure the fluorescence intensity of the iron ion detection fluorescent probe at an excitation wavelength of 290 nm. Determine whether the iron ion content in the magnesium oxide solution meets the content specified in the industry standard according to whether the fluorescence of the sample decreases, so as to screen out magnesium oxide with an iron content meeting the requirements of the industry standard.

[0037] I. Structure and characterization of the iron ion detection fluorescent probe of the present invention;

[0038] (1) Structure analysis: Figure 1 is the structure of the pyrazine-2,3,5,6-tetracarboxylic acid ligand, Figure 2 is the coordination environment of the prepared iron ion fluorescent probe. Each Zn 2+ coordinates with four oxygen atoms and one nitrogen atom, and the coordinated oxygen atoms are from the carboxyl groups of three different ligands. Figure 3It is the two-dimensional structure diagram of the fluorescent probe for iron ion detection.

[0039] (2), Powder diffraction characterization: Figure 4 It is the powder X-ray diffraction pattern of the prepared iron ion fluorescent probe. As Figure 4 shown, the characteristic diffraction peaks in the simulated PXRD and the actually synthesized PXRD correspond well, indicating that the prepared iron ion detection fluorescent probe is a pure phase.

[0040] (3), Infrared spectrum characterization of phase composition: The infrared spectrum of the complex material was tested on an FT-IR spectrometer, and the scanning range was 4000 cm -1 -400 cm -1 . Figure 5 It is the infrared spectrum of the iron ion detection fluorescent probe. An obvious characteristic peak appears at a wavelength of 1631 cm -1 , which belongs to the fully deprotonated carboxyl group, and this is consistent with the structural analysis of the single crystal results.

[0041] II. Calculation of detection limit: The iron ion detection fluorescent probe prepared in Example 1 was taken and oscillated evenly with a series of metal ion solutions with known concentrations to obtain standard samples, and the fluorescence of each standard sample was measured at an excitation wavelength of 290 nm; it was found that the probe has a fluorescence quenching effect on iron ions, as Figure 6 shown.

[0042] III. Calculation of detection limit: The iron ion detection fluorescent probe prepared in Example 1 was taken and oscillated evenly with a series of iron ion solutions with known concentrations to obtain standard samples, and the fluorescence of each standard sample was measured at an excitation wavelength of 290 nm; with the iron ion concentration as the abscissa and the fluorescence intensity as the ordinate, a linear relationship model was constructed and the detection limit was calculated; as Figure 7 and Figure 8 shown.

[0043] IV. Anti-interference detection: The iron ion detection fluorescent probe prepared in Example 1 was taken and oscillated evenly with iron ions and a series of other metal ion solutions with known concentrations (Mg 2+ , Ca 2+ , Al 3+ , SiO2) to obtain standard samples, and the fluorescence of each standard sample was measured at an excitation wavelength of 290 nm; with the added other metal ions as the abscissa and the fluorescence intensity as the ordinate, a bar chart model was constructed, as Figure 9 shown.

[0044] V. Detection of actual samples: Take 1 mg of the iron ion detection fluorescent probe prepared in Example 1 and uniformly mix it with 3 mL of the sample to be tested. Then, measure the fluorescence of the mixed solution to be measured at an excitation wavelength of 290 nm. Determine whether the iron ion content in the sample to be tested meets the content specified in the industry standard based on whether the fluorescence of the sample decreases, so as to screen out magnesium oxide with an iron content meeting the requirements of the industry standard.

[0045] Example 3: This example provides a fluorescence detection method for rapidly detecting the iron content in magnesium oxide, including the following steps:

[0046] Step 1: Accurately weigh 5 mg of pyrazine-2,3,5,6-tetracarboxylic acid and 30 mg of Zn(NO)3 and dissolve them in a mixed solvent of 2.25 mL of N,N-dimethylformamide (DMF) and 0.75 mL of dimethyl sulfoxide (DMSO), and stir for 30 min to obtain a mixed solution.

[0047] Step 2: Place the mixed solution obtained in Step 1 in an oven at 90 °C and continuously heat it for 96 h to obtain white transparent block-shaped crystals. After washing, filtering, drying, and grinding the white transparent block-shaped crystals, an iron ion detection fluorescent probe is obtained. The molecular formula of the iron ion detection fluorescent probe is (Zn2(C8O8N2H2)·DMSO·HCOOH) n 。

[0048] Step 3: Prepare a series of iron ion standard solutions with known concentrations, and the concentrations are: 0 μM, 10 μM, 20 μM, 30 μM, 40 μM, 50 μM, 60 μM.

[0049] Step 4: Take 1 mg of the iron ion detection fluorescent probe obtained in Step 2, add 3 mL of the iron ion standard solution with known concentration prepared in Step 3 to it, mix evenly, and measure its fluorescence intensity at a wavelength of 320 nm.

[0050] Figure 7 is the fluorescence change diagram after adding 3 mL of iron ion standard solutions with different concentrations to the iron ion detection fluorescent probe. From Figure 7 it can be clearly seen that as the iron ion concentration continuously increases, the fluorescence intensity of the iron ion detection fluorescent probe gradually decreases.

[0051] As Figure 8 shown, in the low iron ion concentration range of 0 μM - 300 μM, the linear relationship between the fluorescence intensity of the iron ion detection fluorescent probe and the ion concentration conforms to the Stern-Volme equation: I0 / I = 1 + K SV [M]; I0 represents the fluorescence intensity before the addition of iron ions, I represents the fluorescence intensity after the addition of iron ions, [M] represents the concentration of the analyte (μmol / L, μM), K SVRepresenting the quenching constant (μM -1 ).

[0052] By the detection limit (LOD) formula: LOD = 3σ / K SV , K SV = 0.01203 μM -1 , the detection limit of this iron ion fluorescence probe was calculated to be 1.10 μM. Where σ is the standard deviation value of the fluorescence intensity of 10 blank experiments of the iron ion fluorescence probe without adding any ions. In this example, σ = 0.0044.

[0053] Accurately weigh 0.5 g of dried magnesium oxide into a platinum dish with a volume of 75 mL. Add 4.0 g of anhydrous sodium carbonate and 2.7 g of boric acid and mix evenly. Cover the platinum lid and leave a slight gap. Place it in a high-temperature furnace. First, heat it slowly, and then gradually increase the temperature to 1100 °C ± 25 °C and heat for 10 min. Take out the crucible and cover it with a platinum lid or a watch glass. After the crucible cools slightly, add 55 mL of sulfuric acid (1+9) while stirring and heat in a steam bath until the sample is completely dissolved. After cooling, transfer it to a 250 mL volumetric flask and make up the volume for standby.

[0054] At this time, if the iron ion content of the sample to be measured meets the industry standard regulations, the iron content should be ≤ 0.5%. Converted to concentration according to the following formula 1 and formula 2, it should be less than 125.24 μM. The detection limit of the iron ion fluorescence probe prepared in this example is 1.09 μM < 125.24 μM, and it is proved by the anti-interference experiment that this iron ion detection fluorescence probe is less interfered by other ions, which proves that this iron ion detection fluorescence probe can quickly screen out magnesium oxide with iron content meeting the requirements of the industry standard.

[0055] Formula 1: Fe2O3 + 3H2SO4 = Fe2(SO4)3 + 3H2O;

[0056] Formula 2:

[0057] M is the relative molecular mass of Fe2O3, and the value of M is 159.69 g / mol; m is the mass of MgO weighed, and the value of m is 0.5 g; V is the volume of the solution, and the value of V is 250 mL; C is the concentration of iron ions.

[0058] The fluorescence detection method of the present invention has the following advantages compared with the prior art:

[0059] Using the method of the present invention to screen magnesium oxide with iron content meeting the requirements of the industry standard has the characteristics of rapid response, high selectivity, high sensitivity and visualization, and can realize the rapid detection of iron ions through the change of fluorescence. Compared with the existing iron ion detection technology, this iron ion detection reagent has remarkable effects, simple operation and is easy to implement, and has good market application prospects.

[0060] Among them, sulfuric acid (1+9) usually represents the volume mixing ratio of sulfuric acid and water, that is, 1 volume of concentrated sulfuric acid is mixed with 9 volumes of water.

Claims

1. A fluorescent probe for detecting iron ions, characterized in that, The molecular formula of the fluorescent probe is (Zn2(C8O8N2H2)·DMSO·HCOOH) n 。 2. The fluorescent probe for detecting iron ions according to claim 1, characterized in that The preparation steps of the fluorescent probe are as follows: Step 1: Weigh pyrazine-2,3,5,6-tetracarboxylic acid and Zn(NO)3 and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). After stirring, a mixed solution is obtained; the mass ratio of pyrazine-2,3,5,6-tetracarboxylic acid to Zn(NO)3 is 1:6, and the volume ratio of N,N-dimethylformamide (DMF) to dimethyl sulfoxide (DMSO) is 3:1; Step 2: Place the mixed solution obtained in Step 1 in an oven at 90°C ± 5°C and continuously heat it for 4 to 6 days to obtain white transparent block crystals. After washing, filtering, drying, and grinding the white transparent block crystals, the fluorescent probe is obtained.

3. The fluorescent probe for detecting ferric ions according to claim 2, wherein The stirring time in Step 1 is 30 min - 60 min.

4. Application of the iron ion detection fluorescent probe as described in Claim 1 in the rapid detection of iron content in magnesium oxide.

5. A fluorescence detection method for rapidly detecting the iron content in magnesium oxide, characterized in that, It includes the following steps: Step 1: Weigh 0.5 g of dried magnesium oxide into a platinum crucible. Add 4.0 g of anhydrous sodium carbonate and 2.7 g of boric acid to the platinum crucible and mix evenly. Cover the platinum crucible with a platinum lid and leave a slight gap. Place it in a high-temperature furnace. First, heat it slowly, and then gradually raise the temperature to 1100°C ± 25°C and heat for 10 min. Take out the crucible and cover it with a platinum lid or a watch glass; after the crucible cools slightly, add 55 mL of sulfuric acid solution while stirring and heat it in a steam bath until the sample is completely dissolved. After cooling, transfer it to a volumetric flask and make up the volume to obtain a magnesium oxide solution; Step 2: Take 1 mg of the iron ion detection fluorescent probe in Claim 1, add 3 mL of the magnesium oxide solution prepared in Step 1 to it, mix evenly, and measure the fluorescence intensity of the iron ion detection fluorescent probe at an excitation wavelength of 290 nm.

6. A fluorescence detection method for rapidly detecting the iron content in magnesium oxide according to claim 5, characterized in that, In Step 2, the volume ratio of sulfuric acid to water in the sulfuric acid solution is 1:9.

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