Formaldehyde concentration detection fluorescent probe and preparation method and application thereof

Abstract

The application discloses a formaldehyde concentration detection fluorescent probe and a preparation method and application thereof. The formaldehyde concentration detection fluorescent probe is based on the specific response of amino groups to formaldehyde, and realizes the fluorescence detection of high-concentration formaldehyde for the first time. The formaldehyde concentration detection fluorescent probe is simple, fast and accurate in the commercial formaldehyde detection process, and has strong application value. The application of the formaldehyde concentration detection fluorescent probe in formaldehyde detection has excellent anti-interference ability. Impurities, including sodium ions, chlorine ions, sulfate ions, lead ions, acetaldehyde, iron ions and methanol added as a polymerization inhibitor, which are common in the production process of formaldehyde solution, do not affect the detection result.

Description

Technical Field

[0001] This invention relates to the field of formaldehyde detection technology, specifically to a fluorescent probe for formaldehyde concentration detection, its preparation method, and its application. Background Technology

[0002] Formaldehyde (FA) is widely used in many fields, the most important being the production of formaldehyde-based resins, including urea-formaldehyde, phenol, and melamine-formaldehyde resins, which account for approximately 70% of formaldehyde consumption. In addition, formaldehyde is also used as a disinfectant, preservative, and adhesive in the medical, textile, food, and construction industries. Driven by the growth of various formaldehyde resin markets, the global formaldehyde industry is projected to increase, with global formaldehyde consumption expected to grow at a rate of nearly 5% over the next few years. The Asia-Pacific region has the highest formaldehyde consumption, almost equivalent to the combined consumption of Europe, North America, and Latin America.

[0003] Currently, formaldehyde is mainly produced in the presence of O2 through the oxidative dehydrogenation / partial oxidation of gas-phase methanol. This process relies on silver catalysts (silver contact method) or ferric molybdate catalysts (Formox method). Formaldehyde is chemically reactive, posing high safety risks during long-distance transportation. Therefore, formaldehyde producers are often located close to downstream users, exhibiting a certain regional characteristic. Although in reality, industrial plants directly produce formaldehyde solutions with higher concentrations, formaldehyde with a concentration of 37-40 wt% is used as a standard or commercial product.

[0004] Currently, the concentration testing of formaldehyde aqueous solutions mainly relies on titration. One method involves adding a fixed amount of formaldehyde solution sample to a standard volume of sodium hydroxide solution and hydrogen peroxide solution. The solution is then heated in a steam bath for 30 minutes, cooled, and titrated with a standard volume of hydrochloric acid solution. Another method uses thymolphthalein indicator and a standard sulfuric acid titration solution to titrate a fixed amount of anhydrous sodium sulfite solution until colorless. An accurately weighed formaldehyde solution sample is then added to this solution, and titrated again with the standard sulfuric acid solution, changing the solution from blue to colorless. Titration methods involve multiple steps and are easily affected by various errors introduced during the operation. Summary of the Invention

[0005] This invention addresses the above-mentioned problems by researching and designing a fluorescent probe for formaldehyde concentration detection, its preparation method, and its application. The technical means employed in this invention are as follows:

[0006] A fluorescent probe for formaldehyde concentration detection has the following general structural formula:

[0007]

[0008] A method for preparing a fluorescent probe for formaldehyde concentration detection includes the following steps:

[0009] S1-1: Dissolve the raw material and NaN3 in a DMF / H2O mixed solution and heat, wherein the ratio of the raw material to NaN3 is 1:1 to 1:1.5;

[0010] S1-2: Pour the reaction mixture from step S1-1 into ice water and filter to remove the precipitate;

[0011] S1-3: Dissolve the precipitate in DMF, add it to an aqueous solution of NaHS and stir. The ratio of raw material to NaHS is 1:1 to 1:2. Add ice water to the reaction solution to adjust it to weak acidity, and filter to obtain the solid target product.

[0012] The raw material has the following general structural formula:

[0013]

[0014] An application of the formaldehyde concentration detection fluorescent probe described in this invention in formaldehyde detection.

[0015] Furthermore, the application of the formaldehyde concentration detection fluorescent probe in formaldehyde detection includes the following steps:

[0016] S2-1: Dissolve the formaldehyde concentration detection fluorescent probe in DMSO to prepare a stock solution with a concentration of 5-10 mM;

[0017] S2-2: Take the mother liquor and add it to the formaldehyde aqueous solution to be tested to form a detection mixture. The concentration of the formaldehyde concentration detection fluorescent probe in the detection mixture is 1-50 μM, preferably 10-30 μM, preferably 20 μM. The fluorescence response curve is detected with an excitation wavelength of 429 nm, and the fluorescence intensity at 561 nm is recorded. The concentration of the formaldehyde aqueous solution is calculated based on the working curve.

[0018] Further, the method for obtaining the working curve is as follows: take the mother liquor, add it to the formaldehyde standard solution, the concentration of the formaldehyde concentration detection fluorescent probe is the same as in step S2-2, keep it at room temperature for 10 min, detect the fluorescence response curve, the excitation wavelength is 429 nm, the emission wavelength is 561 nm, record the fluorescence intensity at 561 nm for formaldehyde standard solutions of different concentrations, and plot the formaldehyde concentration of the formaldehyde standard solution and the fluorescence intensity at 561 nm to obtain the working curve.

[0019] Compared with existing technologies, the formaldehyde concentration detection fluorescent probe, its preparation method, and its application described in this invention have the following beneficial effects:

[0020] 1. Existing formaldehyde detection probes reach saturation at higher formaldehyde concentrations, making them unsuitable for detecting commercial formaldehyde solutions. The formaldehyde concentration detection fluorescent probe described in this invention, based on the specific response of amino groups to formaldehyde, achieves fluorescent detection of high-concentration formaldehyde for the first time. It offers a simple, rapid, and accurate detection process for commercial formaldehyde, possessing significant application value.

[0021] 2. The formaldehyde concentration detection fluorescent probe described in this invention has excellent anti-interference ability in the application of formaldehyde detection. Common impurities in formaldehyde solution during the production process, including sodium ions, chloride ions, sulfate ions, lead ions, acetaldehyde, iron ions, and methanol added as a polymerization inhibitor, do not affect the detection results.

[0022] 3. The formaldehyde concentration detection fluorescent probe described in this invention is simpler to operate than existing titration methods for formaldehyde detection, generates less waste chemical reagents, and has a shorter testing time. Experimenters do not need to be exposed to formaldehyde under open titration conditions, reducing human hazards. Attached Figure Description

[0023] Figure 1 This diagram illustrates the detection mechanism of the fluorescent probe for formaldehyde concentration detection as described in an embodiment of the present invention.

[0024] Figure 2 The formaldehyde concentration detection fluorescent probe described in this embodiment of the invention presents response curves to different concentrations of formaldehyde.

[0025] Figure 3 This is a working curve of the fluorescent probe for formaldehyde concentration detection described in an embodiment of the present invention.

[0026] Figure 4 The diagram shows the anti-interference capability of the fluorescent probe for formaldehyde concentration detection described in the embodiments of the present invention. In the diagram, (1) FA (3.33mM); (2) methanol (5mM); (3) FeCl3 (5mM); (4) NaCl (5mM); (5) NaSO4 (5mM); (6) blank; (7) acetaldehyde (5mM); (8) Pb(CH3COO)2 (5mM).

[0027] Figure 5 This is a high-resolution mass spectrum of the formaldehyde concentration detection fluorescent probe described in this invention.

[0028] Figure 6 The NMR spectrum of the fluorescent probe for formaldehyde concentration detection described in this invention is shown. Detailed Implementation

[0029] Example 1

[0030] Synthesis of a fluorescent probe for formaldehyde concentration detection:

[0031] 6-Bromo-1h,3h-benzo[de]isochromium-1,3-dione (1 mmol) and NaN3 (1 mmol) were dissolved in DMF / H2O (v / v, 10 / 1, 10 mL) and stirred at 80 °C for 2 h. The reaction solution was then poured into 20 mL of ice water, and the precipitate was filtered off. The precipitate was dissolved in 10 mL of DMF, and 2 mL of NaHS (1.5 mmol) aqueous solution was added. The mixture was stirred at 90 °C for 2 h. Then, the reaction solution was added to ice water to adjust the pH to weakly acidic. Finally, the solution was filtered to obtain a pale yellow solid.

[0032] Example 2

[0033] Synthesis of a fluorescent probe for formaldehyde concentration detection:

[0034] 6-Bromo-1h,3h-benzo[de]isochromium-1,3-dione (1 mmol) and NaN3 (1.5 mmol) were dissolved in DMF / H2O (v / v, 10 / 1, 10 mL) and stirred at 80 °C for 2 h. The reaction solution was then poured into 20 mL of ice water, and the precipitate was filtered off. The precipitate was dissolved in 10 mL of DMF, and 2 mL of NaHS (2 mmol) aqueous solution was added. The mixture was stirred at 90 °C for 2 h. Then, the reaction solution was added to ice water to adjust the pH to weakly acidic. Finally, the mixture was filtered to obtain a pale yellow solid.

[0035] Example 3

[0036] Synthesis of a fluorescent probe for formaldehyde concentration detection:

[0037] 6-Bromo-1h,3h-benzo[de]isochromium-1,3-dione (1 mmol) and NaN3 (1.5 mmol) were dissolved in DMF / H2O (v / v, 10 / 1, 10 mL) and stirred at 80 °C for 2 h. The reaction solution was then poured into 20 mL of ice water, and the precipitate was filtered off. The precipitate was dissolved in 10 mL of DMF, and 2 mL of NaHS (1 mmol) aqueous solution was added. The mixture was stirred at 90 °C for 2 h. Then, the reaction solution was added to ice water to adjust the pH to weakly acidic. Finally, the solution was filtered to obtain a pale yellow solid.

[0038] Example 4

[0039] Formaldehyde response of a fluorescent probe for formaldehyde concentration detection:

[0040] The formaldehyde concentration detection fluorescent probe of this invention was dissolved in DMSO to prepare a stock solution with a concentration of 10 mM. Formaldehyde standard solutions of different concentrations and specific volumes were prepared. The stock solution was added to the formaldehyde standard solutions, resulting in a concentration of 20 μM. After mixing, the solutions were kept at room temperature for 10 min. The fluorescence response curve of the mixed solution was detected using a fluorescence spectrometer. The excitation wavelength was 429 nm, and the emission wavelength was 561 nm. The fluorescence intensity at 561 nm increased with increasing formaldehyde concentration. The fluorescence intensity at 561 nm for different formaldehyde standard solutions was recorded.

[0041] Example 5

[0042] Selectivity of a fluorescent probe for formaldehyde concentration detection:

[0043] Selective test solutions of different concentrations were prepared, namely (1) FA (3.33 mM); (2) Methylalcohol (5 mM); (3) FeCl3 (5 mM); (4) NaCl (5 mM); (5) NaSO4 (5 mM); (6) probe alone; (7) acetaldehyde (5 mM); and (8) Pb(CH3COO)2 (5 mM). The mother liquor from Example 1 was added to the selective test solutions at a concentration of 20 μM. After mixing, the solutions were kept at room temperature for 10 min. The fluorescence response curve of the mixed solution was detected using a fluorescence spectrometer. The excitation wavelength was 429 nm, and the emission wavelength was 561 nm. The fluorescence intensity at 561 nm for different formaldehyde standard solutions was recorded.

[0044] Example 6

[0045] Application of a fluorescent probe for formaldehyde concentration detection:

[0046] The formaldehyde concentration detection fluorescent probe of this invention determined the concentration of the commercial formaldehyde solution to be 14.13 mol / L, which translates to a mass percentage of 39.2%. Using the formaldehyde solution determination method in GB / T 685-2013, the concentration of the commercial formaldehyde solution was determined to be 38.6%.

[0047] The detection mechanism of the formaldehyde concentration detection fluorescent probe described in this embodiment of the invention is as follows: Figure 1 As shown, the formaldehyde concentration detection fluorescent probe of the present invention can specifically bind to formaldehyde molecules, and achieve the purpose of detection by changing the molecular fluorescence signal. Figure 2 The above are the response curves of the fluorescent probe for formaldehyde concentration detection described in the embodiments of the present invention to different concentrations of formaldehyde. It can be seen that the fluorescent probe for formaldehyde concentration detection described in the embodiments of this application can respond rapidly in the formaldehyde concentration range of 0.01-13.55 mol / L. Figure 3The image shows the working curve of the fluorescent probe for formaldehyde concentration detection according to an embodiment of the present invention. It can be seen that the fluorescent probe for formaldehyde concentration detection can respond linearly to formaldehyde concentration over a wide range of formaldehyde concentrations, with a correlation coefficient of up to 0.98. Figure 4 The diagram shows the anti-interference capability of the fluorescent probe for formaldehyde concentration detection described in this embodiment of the invention. It can be seen that common impurities in the formaldehyde solution during the production process, including sodium ions, chloride ions, sulfate ions, lead ions, acetaldehyde, iron ions, and methanol added as a polymerization inhibitor, do not affect the detection results. Figure 5 Mass spectrometry revealed that the peaks at 214.0499 and 236.0318 matched the ion peaks of the target compound. Figure 6 The 1H NMR spectrum showed that the values ​​of δ8.69 (d, 1H), δ8.44 (d, 1H), δ8.19 (d, 1H), δ7.78 (d, 2H), δ7.70 (d, 1H), and δ6.88 (d, 1H) ppm matched the chemical shifts and numbers of hydrogen atoms in the target compound.

[0048] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for detecting formaldehyde concentration, characterized in that, Includes the following steps: S1: Dissolve the fluorescent probe for formaldehyde concentration detection in DMSO to prepare a stock solution with a concentration of 5~10 mM; S2: Take the mother liquor and add it to the formaldehyde aqueous solution to be tested to form a detection mixture. The concentration of the formaldehyde concentration detection fluorescent probe in the detection mixture is 1-50 μM. The fluorescence response curve is detected with an excitation wavelength of 429 nm. The fluorescence intensity at 561 nm is recorded. The concentration of the formaldehyde aqueous solution is calculated based on the working curve. The formaldehyde concentration detection fluorescent probe has the following structural formula: 。 2. The formaldehyde concentration detection method according to claim 1, characterized in that, The preparation method of the formaldehyde concentration detection fluorescent probe described in S1 is as follows: S1-1: Dissolve the raw material and NaN3 in a DMF / H2O mixed solution and heat, wherein the ratio of the raw material to NaN3 is 1:1 to 1:1.5; S1-2: Pour the reaction mixture from step S1-1 into ice water and filter to remove the precipitate; S1-3: Dissolve the precipitate in DMF, add it to an aqueous solution of NaHS and stir. The ratio of raw material to NaHS is 1:1 to 1:

2. Add ice water to the reaction solution to adjust it to weak acidity, and filter to obtain the solid target product. The general structural formula of the raw material is: 。 3. The formaldehyde concentration detection method according to claim 1, characterized in that, The method for obtaining the working curve described in S2 is as follows: Take the mother liquor and add it to the formaldehyde standard solution. The concentration of the formaldehyde concentration detection fluorescent probe is the same as in step S2. Keep it at room temperature for 10 minutes, detect the fluorescence response curve, excite the wavelength at 429 nm, and record the fluorescence intensity at 561 nm for different concentrations of formaldehyde standard solution. Plot the formaldehyde concentration of the formaldehyde standard solution and the fluorescence intensity at 561 nm to obtain the working curve.

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