Fluoride ion chromogenic agent and application thereof in fluoride ion colorimetric detection

Abstract

The application discloses a fluorine ion chromogenic agent and application thereof in fluorine ion colorimetric detection. The chromogenic agent has two hydrophilic hydroxyl groups and a hydrophobic aromatic ring system, can be applied to various organic solvent systems such as ethanol, acetonitrile, DMF and DMSO or mixed systems of the organic solvents and water, has a wider application range in actual detection, does not need to add strong acid or strong base and other auxiliary reagents in the detection process, simplifies the operation, is more convenient for on-site detection, has a wider upper and lower limit for visual colorimetric detection of fluorine ions, has no interference on the detection process for common ions such as I ‑ , Br ‑ , Cl ‑ , PO4 3‑ and Ac ‑ , and has good stability.

Description

Technical Field

[0001] This invention belongs to the field of ion detection technology, which relates to the synthesis and application of compounds for colorimetric detection of anions. Specifically, it relates to a compound with specific structure and properties and its application in the colorimetric detection of fluoride ions. Background Technology

[0002] In anion recognition, anions act as guest molecules, interacting with the host chromogenic agent to cause a color change in the solution, which can then be detected by colorimetry. Colorimetric detection methods are widely studied and applied due to their advantages, such as not requiring expensive instruments and being simple to operate. Fluoride ions are anions that have a significant impact on living systems. Excessive intake of fluoride ions can lead to fluorosis, causing fluorosis-related osteosclerosis, bone hardening, and bone hyperplasia, restricting joint movement, and even paralysis, resulting in complete loss of working ability. Therefore, fluoride ion detection has a huge practical need. The development of convenient and rapid fluoride ion detection methods has received increasing attention.

[0003] For example, patent CN 1730485A uses 1,10-phenanthroline-5,6-dione and 2,4-dinitrophenylhydrazine to synthesize a ligand to prepare a complex; patent CN100483113C uses 4,5-diazonyl-9-one and 2,4-dinitrophenylhydrazine to synthesize a ligand to prepare a complex; and patent CN102942541B uses an acceptor compound for colorimetric detection of fluoride ions. These methods either require very complex synthetic steps or require noble metals such as ruthenium, palladium, and rhodium to form complexes, which is not conducive to the widespread use of these methods. Furthermore, due to the solubility issues of the colorimetric reagents, these methods are difficult to use in solvents with different properties, making them unsuitable for the detection of different types of fluoride-containing wastewater in different industries. The alizarin sulfonate zirconium visual colorimetric method [HJ 487-2009] utilizes the colorless alizarin to form a red complex with zirconium salt. The addition of fluoride ions competitively forms zirconium fluoride, causing the colorimetric reagent to decolorize, thus detecting fluoride ions. This method is only suitable for detecting fluoride ions in water, requires a large amount of strong acid, and has low sensitivity due to its decolorization detection method. The fluoride reagent spectrophotometric method [HJ 488-2009] utilizes the alizarin derivative and lanthanum salt to form a purple-red complex. The addition of fluoride ions forms a blue ternary complex. Because it is a color-changing detection method, it has high sensitivity. However, this method is based on a spectrophotometer and is not suitable for rapid on-site detection. Summary of the Invention

[0004] The purpose of this invention is to provide a compound colorimetric agent.

[0005] Another object of the present invention is to provide a method for synthesizing the compound.

[0006] Another objective of this invention is to provide the application of this compound as a colorimetric reagent in the colorimetric detection of fluoride ions.

[0007] The technical solution to achieve the first objective of this invention is:

[0008] A colorimetric reagent, named 9-(2-(2,4-dinitrophenyl)hydrazone)-9H-fluorene-2,7-diol, has the following structure:

[0009]

[0010] The technical solution to achieve the second objective of this invention is:

[0011] A method for synthesizing a compound colorimetric reagent, comprising:

[0012] The step of preparing the target product involves reacting a solution of 2,4-dinitrophenylhydrazine and a solution of 2,7-dihydroxy-9-fluorenone in a phosphoric acid catalyst.

[0013]

[0014] Preferably, acetonitrile is used as the solvent for the 2,4-dinitrophenylhydrazine solution.

[0015] Ethanol is preferred as the solvent for the 2,7-dihydroxy-9-fluorenone solution.

[0016] Preferably, the reaction temperature is 60℃ and the reaction time is not less than 3 hours.

[0017] Preferably, the molar ratio of 2,4-dinitrophenylhydrazine and 2,7-dihydroxy-9-fluorenone is 1:1.

[0018] The technical solution to achieve the third objective of this invention is:

[0019] Application of the compound colorimetric reagent in the colorimetric detection of fluoride ions.

[0020] Preferably, the colorimetric reagent of the compound is prepared by mixing the soluble copper salt with the compound at a molar ratio of 1:1 to form a solution of 1.7 × 10⁻⁶. -4 mol / L colorimetric detection solution.

[0021] Specifically, the solvent in the colorimetric detection solution can be a variety of organic solvent systems such as ethanol, acetonitrile, DMF, DMSO, or a mixture of these organic solvents and water.

[0022] Furthermore, the properties of the compound colorimetric agent are as follows:

[0023] (1) Applicability: It can detect fluoride ions, and the positive reaction color is purple;

[0024] (2) Development time: not more than 2 minutes;

[0025] (3) Detection range: 0-5ppm, detection limit: 0.2ppm;

[0026] (4) Stability: Blank and reaction results are stable in air at room temperature for 72 hours and stable in a closed container at room temperature and protected from light for 6 months.

[0027] (5) Anti-interference: Common ions such as I - , Br - Cl - PO4 3- and Ac - It does not interfere with the detection process.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The raw materials for the synthesis of this colorimetric reagent compound are cheap and readily available, and the reaction process is simple;

[0030] (2) The colorimetric reagent compound has a wider upper and lower limit for visual colorimetric detection of fluoride ions, which is beneficial for practical applications;

[0031] (3) The colorimetric reagent compound does not require the addition of auxiliary reagents such as strong acid or strong base during the detection process, which simplifies the operation and makes it more convenient for on-site detection;

[0032] (4) This colorimetric system is made into a standard colorimetric tube by adding fluoride ion standard. It is placed in the colorimetric tube, sealed and protected from light. It can be stored at room temperature for more than 6 months without color change. Therefore, it can be prepared in advance and is especially suitable for rapid on-site detection.

[0033] (5) Unlike existing fluoride ion colorimetric reagents, the colorimetric reagent compound of the present invention has two hydrophilic hydroxyl groups and a hydrophobic aromatic ring system coexisting, which can be applied to a variety of organic solvent systems such as ethanol, acetonitrile, DMF, DMSO or mixed systems of these organic solvents and water, and has a wider range of practical applications.

[0034] (6) Unlike existing visual colorimetric and photometric detection methods for fluoride ions, this invention utilizes a soluble copper salt and a colorimetric reagent to form a light yellow colorimetric system. After the addition of fluoride ions, the solution changes to purple. This change from light yellow to purple is particularly sensitive to visual colorimetry and is more suitable for visual detection than the red to colorless fading method of the national standard method [HJ 487—2009].

[0035] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the inventive subject matter of this application, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the inventive subject matter of this application.

[0036] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0037] Figure 1 Colorimetric graphs of fluoride ion solutions of different concentrations (concentration decreases from left to right).

[0038] Figure 2 Colorimetric diagrams of different anions (from left to right: I...) - , Br - Cl - PO4 3- F - and Ac - ). Detailed Implementation

[0039] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0040] In this invention, various aspects of the invention are described with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of the invention are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0041] Furthermore, the present invention is illustrated by the following examples, but these examples are merely illustrative and should not be construed as limiting the scope or application of the invention. Unless otherwise specified, all materials used in this invention are commercially available.

[0042] (I) Synthesis of compound colorimetric reagents

[0043] The structures and reaction equations of the raw materials and products for synthesizing the chromogenic agent 9-(2-(2,4-dinitrophenyl)hydrazone)-9H-fluorene-2,7-diphenol of the present invention are shown below:

[0044]

[0045] (II) Detection of fluoride ion solutions by colorimetric reagents

[0046] The color developer and soluble copper salt were mixed at a molar ratio of 1:1 to prepare a solution of 1.7 × 10⁻⁶. -4 The mol / L colorimetric detection solution can be prepared using different solvents. This solution is a yellow, transparent liquid. Add a solution containing fluoride ions; the solvent can also be prepared using different solvents. Shake well, let stand for 2 minutes, and then observe the color development.

[0047] Example 1

[0048] 1. Synthesis of colorimetric reagent compounds

[0049] Weigh 0.198 g (1 mmol) of 2,4-dinitrophenylhydrazine into a 100 mL round-bottom flask, add 25 mL of acetonitrile to dissolve it completely, then weigh 0.212 g (1 mmol) of 2,7-dihydroxy-9-fluorenone and dissolve it in 25 mL of ethanol. Transfer the dissolved ethanol solution to the flask and heat while stirring. When the temperature reaches 60 °C, add 5 mL of phosphoric acid and maintain the reaction at 60 °C for three hours. After the reaction stops and the mixture cools to room temperature, filter the solution, wash the product with ethanol, and dry under vacuum. Recrystallize from a mixture of ethanol and DMF (ethanol to DMF volume ratio 1:2–1:5) to obtain the target product in 81% yield.

[0050] The product synthesized in this invention was successfully synthesized through melting point analysis, nuclear magnetic resonance (NMR) spectroscopy, infrared spectroscopy, elemental analysis, and ultraviolet spectroscopy. The NMR spectral data of the chromogenic agent are shown below.

[0051] 1 H NMR (400MHz, DMSO) δ11.75(s,1H),9.92(s,1H),9.63(s,1H),8.94(d,J=2.5Hz,1H),8.54(dd,J=9.4,2.5Hz,1H),8.25(d,J=9. 6Hz,1H),7.71–7.51(m,2H),7.46(d,J=8.1Hz,1H),7.25(d,J=2.2Hz,1H),6.94(d,J=8.2Hz,1H),6.80(dd,J=8.2,2.1Hz,1H).

[0052] 2. Detection of fluoride ion solutions of different concentrations by colorimetric reagents

[0053] The color developer and copper chloride were mixed at a molar ratio of 1:1 to prepare a solution of 1.7 × 10⁻⁶. -4The mol / L colorimetric detection solution is a mixture of DMSO and water (9:1 volume ratio), resulting in a yellow, transparent liquid. Take nine 5 mL standard colorimetric tubes and add 2 mL of the yellow colorimetric detection solution to each. Then, sequentially add 2 mL of fluoride ion standard solutions with concentrations of 0 ppm, 0.2 ppm, 0.5 ppm, 1.0 ppm, 1.5 ppm, 2.0 ppm, 3.0 ppm, 5.0 ppm, and 10.0 ppm. The fluoride ion standard solutions are also a mixture of DMSO and water (9:1 volume ratio). Shake well and let stand. The color development will stabilize after 2 minutes, at which point the color can be observed. The color development results are as follows. Figure 1 As shown. Figure 1 In the diagram, from right to left, the fluoride ion concentration gradually increases. After adding fluoride ions, the solution gradually changes from yellow to purple as the fluoride ion concentration increases. The visual colorimetric detection limit is 0.2 ppm, lower than the national requirement of 1 ppm for fluoride ion content in drinking water. This indicates that this method has practical application value. The detection limit is 5 ppm, which is twice as high as the national standard colorimetric detection method, making it more convenient for practical applications.

[0054] Example 2

[0055] 1. Synthesis of colorimetric reagent compounds

[0056] The synthesis steps are the same as in Example 1, and will not be repeated here.

[0057] 2. Detection of the colorimetric reagent's resistance to common coexisting anions

[0058] The color developer and copper chloride were mixed at a molar ratio of 1:1 to prepare a solution of 1.7 × 10⁻⁶. -4 The colorimetric detection solution is a mixture of DMSO and water (9:1 volume ratio), and is a yellow, transparent liquid. Take six 5 mL standard colorimetric tubes and add 2 mL of the yellow colorimetric detection solution to each. Then, add common coexisting interfering ions, such as 100 ppm of IgA, to the yellow colorimetric detection solution sequentially. - , Br - Cl - PO4 3- and Ac - The solvent is a mixture of DMSO and water (volume ratio 9:1). Shake well, let stand for 2 minutes, and then observe the color development results. Figure 2 As shown. Figure 2 Counting from left to right, the colorimetric tubes with high concentrations of coexisting interfering ions (numbered 1, 2, 3, 4, and 6) did not show any color change, while the colorimetric tube with 2 ppm of fluoride ions (numbered 5) showed a distinct purple color. This indicates that the colorimetric reagent described in this invention has strong selectivity and significant practical detection application value.

[0059] Example 3

[0060] 1. Synthesis of colorimetric reagent compounds

[0061] The synthesis steps are the same as in Example 1, and will not be repeated here.

[0062] 2. Detection of fluoride ion-containing samples using colorimetric reagents

[0063] The color developer and copper chloride were mixed at a molar ratio of 1:1 to prepare a solution of 1.7 × 10⁻⁶. -4 The mol / L colorimetric detection solution is a mixture of acetonitrile, ethanol, and water (volume ratio 5:4:1), resulting in a yellow, transparent liquid. Take nine 5 mL standard colorimetric tubes and add 2 mL of the yellow colorimetric detection solution to each. Then, sequentially add 2 mL of fluoride ion standard solutions with concentrations of 0 ppm, 0.2 ppm, 0.5 ppm, 1.0 ppm, 1.5 ppm, 2.0 ppm, 3.0 ppm, 4.0 ppm, and 5.0 ppm, respectively, a mixture of acetonitrile, ethanol, and water (volume ratio 5:4:1). Shake well, seal, and label the top of each tube with a concentration. These tubes will serve as standard colorimetric tubes for visual colorimetric comparison. Take another 5 mL colorimetric tube, add 2 mL of yellow colorimetric detection solution, then add 2 mL of the sample solution to be tested. The sample solution is a mixture of acetonitrile and ethanol containing a small amount of water. Shake well. If the solution turns purple, it indicates the presence of fluoride ions in the sample. Compare the sample colorimetric tube with the standard colorimetric tube in turn. The concentration value on the standard colorimetric tube with the closest color can be regarded as the concentration value of fluoride ions in the sample. If the concentration of fluoride ions in the sample is too high and exceeds the detection limit, dilute the sample 10 times each time with a mixture of acetonitrile, ethanol and water (volume ratio 5:4:1), and then perform the above steps until a result close to the color of the standard colorimetric tube is obtained.

[0064] Example 4

[0065] 1. Synthesis of colorimetric reagent compounds

[0066] The synthesis steps are the same as in Example 1, and will not be repeated here.

[0067] 2. Detection of fluoride ion-containing samples using colorimetric reagents

[0068] The color developer and copper chloride were mixed at a molar ratio of 1:1 to prepare a solution of 1.7 × 10⁻⁶. -4The mol / L colorimetric detection solution is a mixture of ethanol and water (volume ratio 1:1), resulting in a yellow liquid. Take nine 5 mL standard colorimetric tubes and add 2 mL of the yellow colorimetric detection solution to each. Then, sequentially add 2 mL of fluoride ion standard solutions with concentrations of 0 ppm, 0.2 ppm, 0.5 ppm, 1.0 ppm, 1.5 ppm, 2.0 ppm, 3.0 ppm, 4.0 ppm, and 5.0 ppm, respectively, using a 1:1 mixture of ethanol and water. Shake well, seal, and label the top of each tube with a concentration. These tubes will serve as standard colorimetric tubes for visual colorimetric comparison. Take another 5 mL colorimetric tube, add 2 mL of the yellow colorimetric detection solution, and then add 2 mL of the sample solution to be tested. This sample solution is a mixture of water and ethanol. Shake well. If the solution turns purple, it indicates the presence of fluoride ions in the sample. Compare the sample colorimetric tube with the standard colorimetric tubes sequentially; the concentration value on the standard colorimetric tube with the closest color is considered the concentration of fluoride ions in the sample. If the concentration of fluoride ions in the sample is too high and exceeds the detection limit, dilute the sample 10 times with a mixture of ethanol and water (volume ratio 1:1) each time, and then perform the detection as described above until a result close to the color of the standard color-changing tube is obtained for reading.

[0069] Examples 3 and 4 illustrate that the present invention is also applicable to other types of solvent systems.

[0070] Example 5

[0071] 1. Synthesis of colorimetric reagent compounds

[0072] The synthesis steps are the same as in Example 1, and will not be repeated here.

[0073] 2. Colorimetric results of copper-free colorimetric reagents for fluoride ions

[0074] When the colorimetric reagent of the present invention is not mixed with copper salt, the resulting colorimetric detection solution (solvent as in Example 1) is purple, and no obvious change is observed after adding fluoride ion solution.

[0075] Example 6

[0076] 1. Synthesis of colorimetric reagent compounds

[0077] The synthesis steps are the same as in Example 1, and will not be repeated here.

[0078] 2. Add other metal salts to the color developer

[0079] When other common metal salts, such as soluble iron, potassium, sodium, calcium, magnesium, aluminum, zinc, and nickel salts, are added to the colorimetric reagent of this invention, the colorimetric detection solution (solvent as in Example 1) turns purple or purplish-brown. No obvious changes were observed after adding fluoride ion solution.

[0080] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for detecting fluoride ions, characterized in that, A compound with structure i is used as a colorimetric reagent for detecting fluoride ions, the colorimetric reagent having the following structure: ； ⅰ。 2. The application of a colorimetric reagent for fluoride ion detection in colorimetric detection of fluoride ions, characterized in that, The colorimetric reagent has the following structure: 。 3. The application as described in claim 2, characterized in that, The colorimetric reagent was prepared by mixing the soluble copper salt with the reagent at a molar ratio of 1:1 to form a solution of 1.7 × 10⁻⁶. -4 A solution of mol / L was used as the colorimetric detection solution.

4. A fluoride ion detection device, wherein the device is a test strip, a reagent kit, or a standard colorimetric tube, characterized in that, It includes a colorimetric reagent for fluoride ion detection methods and a soluble copper salt, the colorimetric reagent having the following structure: 。

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