A fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene and a preparation method thereof

Abstract

The present invention relates to a fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene and a preparation method thereof. The fluorescent test paper body is loaded with isoazatrimeric indene, and the isoazatrimeric indene is connected to the cellulose in the test paper in the form of a covalent bond. The fluorescent test paper emits purple fluorescence under 365 nm ultraviolet light. When it contacts a dilute solution of explosives (mainly electron-deficient aromatic compounds), the fluorescence of the isoazatrimeric indene is rapidly quenched, thereby realizing rapid detection of aromatic nitro explosives. The advantages of the present invention are: the test paper preparation process is simple and rapid, the cost is low, the detection reproducibility is good, and it can be used for rapid qualitative detection of aromatic nitro explosives and semi-quantitative detection of aromatic nitro explosive concentrations.

Description

Technical Field

[0001] The invention relates to a fluorescent test paper for detecting aromatic nitro compounds and a preparation method thereof, as well as a method for quickly detecting explosives using the test paper, and belongs to the field of organic compound detection. Background Art

[0002] Detecting explosives through simple and practical methods has become a vital issue. At present, the most common explosives are still various aromatic nitro compounds, such as trinitrotoluene (TNT), trinitrophenol (TNP), dinitrobenzene (DNB), etc. Researchers have been committed to developing cost-effective, convenient, applicable, rapid and sensitive methods for detecting explosives. At present, various explosive detection technologies, such as gas chromatography-mass spectrometry (GC-MS), surface enhanced Raman spectroscopy (SERS) and electrochemical methods, although they can accurately detect explosives, have the disadvantages of expensive instruments, complex operations, and inconvenient to carry. Therefore, the development of low-cost test strips that can be used for rapid detection of explosives has become an important issue in the field of explosive detection. Summary of the invention

[0003] The purpose of the present invention is to provide a fluorescent test paper for detecting aromatic nitro compound explosives based on isoazatrimeric indene, and a method for quickly detecting explosives using the test paper.

[0004] The isoazatrimeric indene fragments on the test paper can interact with aromatic nitro compounds, resulting in changes in fluorescence intensity. This effect is the key to explosive detection. The principle is as follows:

[0005] Isoazatrimer indene is an electron-rich aromatic compound. After absorbing photons, it generates excitons through transition, and then the excitons return to the ground state to generate fluorescence. When isoazatrimer indene comes into contact with aromatic nitro compounds, a charge transfer complex is formed. At this time, the excitons generated by the excitation of isoazatrimer indene are first transferred to the excited state of the electron-deficient aromatic compound through energy or electron transfer, and then return to the ground state of isoazatrimer indene. The process of energy or electron transfer is accompanied by the weakening or quenching of fluorescence, thereby realizing the detection of explosives, such as Figure 1 shown.

[0006] A fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene, wherein the test paper body is loaded with isoazatrimeric indene, which is connected to the cellulose macromolecule in the test paper through a covalent bond; the structural formula of the isoazatrimeric indene is as follows:

[0007] .

[0008] The preparation method of the above-mentioned isoazatrimeric indene comprises the following steps:

[0009] Step 1 (Synthesis of nitrosobenzene): Add 0.5-1.1 g sodium tungstate dihydrate and 20-30 mL 30 wt% hydrogen peroxide solution to a dry container, add 20-25 mL aniline dropwise (about 0.3-1.5 mL / min) under ice bath, add 3-5 mL 30 wt% hydrogen peroxide solution every 15 min, add twice in total, stir for 10-15 min after adding aniline. Filter and drain the reactant, wash with cold ethanol solution, and dry naturally to obtain a light yellow-green solid, namely nitrosobenzene.

[0010] Step 2 (Synthesis of isoazatrimeric indene precursor): Add 10-16 g indole and 10-13 g chloroacetic acid to a dry container, and then add 30-50 mL dichloromethane to completely dissolve the reactants. Weigh 10-15 g nitrosobenzene, dissolve it in 20-35 mL dichloromethane and place it in a constant pressure dropping funnel. Add the dichloromethane solution of nitrosobenzene dropwise to the round-bottom flask, control the dropping speed to 2-5 s per drop, and react at room temperature for 7-14 h after the dropping is completed. Filter and wash with dichloromethane 3-6 times to obtain a dark green solid, i.e., isoazatrimeric indene precursor.

[0011] Step 3 (Synthesis of isoazatrimer indene): Add 2.5-3 g of isoazatrimer indene precursor to a dry container, weigh 0.8-0.9 g of phenylhydrazine, dissolve in 25-30 mL of acetonitrile, and drop the acetonitrile solution of phenylhydrazine into the container drop by drop, control the drop rate to 3-5 s per drop, and stir continuously during the drop addition. After the drop addition is completed, react at room temperature for 3-6 h. Filter and wash with cold acetonitrile several times to obtain an off-white solid, namely isoazatrimer indene.

[0012] The method for preparing the fluorescent test paper for rapid detection of aromatic nitro explosives comprises the following steps:

[0013] Step 1: Weigh 0.3-0.6 g of isocyanate, 0.4-0.8 g of potassium hydroxide, and 1.0-2.0 g of epichlorohydrin, add them into a round-bottom flask, add 5-15 mL of tetrahydrofuran into the round-bottom flask, and react at 80°C for 1-5 h.

[0014] Step 2: Immerse the cut qualitative filter paper in the above-mentioned mixed solution, take it out after 1-60 minutes, and dry it to obtain fluorescent test paper for detecting explosives.

[0015] The size of the paper piece is 2-4 cm×3-6 cm.

[0016] The method for quickly detecting explosives using the above-mentioned fluorescent test paper is as follows: a dilute solution of the sample to be tested is dropped onto the fluorescent test paper, and the change in fluorescence intensity of the fluorescent test paper is observed under 365 nm ultraviolet light. When the sample contains aromatic nitro compound explosives, a significant decrease in fluorescence intensity can be observed. This method can be used for rapid qualitative detection of aromatic nitro explosives and semi-quantitative detection of aromatic nitro explosive concentrations.

[0017] The explosive is trinitrotoluene (TNT), trinitrophenol (TNP), dinitrobenzene (DNB) and other electron-deficient aromatic compounds or a mixture thereof.

[0018] In practical applications, the dilute solution of the sample to be tested can be directly dropped onto the fluorescent test paper for detection, or the dilute solution of the sample to be tested can be appropriately concentrated before detection according to the situation.

[0019] Compared with the prior art, the invention has the advantages of simple and rapid test paper preparation, low cost, good detection reproducibility, and can be used for rapid qualitative detection of aromatic nitro explosives and semi-quantitative detection of aromatic nitro explosive concentrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Explosives detection principles;

[0021] Figure 2 The fluorescence response behavior diagram of the test paper in Example 1 after adding aromatic nitro compound explosives, from left to right are the test paper without adding aromatic nitro explosives, and the test paper with dichloromethane solution of trinitrotoluene (TNT), trinitrophenol (TNP), and dinitrobenzene (DNB) added;

[0022] Figure 3 This is a concentration gradient experiment for explosive concentration detection. The first row of five pictures from left to right are respectively -5 mol / L、5.44×10 -5 mol / L、2.27×10 -4 mol / L、1.37×10 -3 mol / L、6.80×10 - 3 mol / L 1,4-dinitrobenzene solution, the grayscale image, the second row of five images from left to right are respectively the test paper dripping concentration of 1.36×10 -2 mol / L、2.72×10 -2 mol / L、5.44×10 -2 mol / L、 1.09×10 -1 mol / L、 2.18×10 -1 Grayscale image after mol / L 1,4-dinitrobenzene solution;

[0023] Figure 4 This is the working curve for semi-quantitative detection of explosives. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to specific implementation examples.

[0025] Example 1

[0026] The reaction formula involved in the synthesis route of isoazatrimeric indene is as follows:

[0027]

[0028] Synthesis of nitrosobenzene (B): Sodium tungstate dihydrate (1.02 g, 3.09 mmol) and 30 wt% hydrogen peroxide solution (20 mL) were added to a 100 mL round-bottom flask. Aniline was added dropwise (about 0.333 mL / min, 20 mL in total) under an ice bath. 3 mL of 30 wt% hydrogen peroxide solution was added every 15 min for a total of 2 additions. After the addition of aniline was completed, the mixture was stirred for 10 min. The reactants were filtered and dried, washed with cold ethanol solution, and dried naturally to obtain a pale yellow-green solid, namely nitrosobenzene.

[0029] Synthesis of isoazatrimeric indene precursor (C): Indole (15.7 g, 134 mmol) and chloroacetic acid (12.6 g, 134 mmol) were added to a 250 mL round-bottom flask, and then dichloromethane (30 mL) was added to completely dissolve the reactants. Separately, nitrosobenzene (14.3 g, 134 mmol) was weighed, dissolved in dichloromethane (30 mL) and placed in a constant pressure dropping funnel. The dichloromethane solution of nitrosobenzene was added dropwise to the round-bottom flask, and the drop rate was controlled to be 5 s per drop. After the dropwise addition was completed, the reaction was allowed to react at room temperature for 12 h. Filtered and washed with dichloromethane 3 times to obtain a dark green solid, i.e., isoazatrimeric indene precursor (3.90 g, 26%).

[0030] Synthesis of isoazatrimer indene (E): Add isoazatrimer indene precursor (2.50 g, 7.24 mmol) to a 100 mL round-bottom flask, accurately weigh phenylhydrazine (0.85 g, 7.86 mmol), dissolve in acetonitrile (25 mL), and add the acetonitrile solution of phenylhydrazine dropwise into the round-bottom flask, control the drop rate to 5 s per drop, and stir continuously during the dropwise addition. After the dropwise addition is completed, react at room temperature for 3 h. Filter and wash with cold acetonitrile several times to obtain an off-white solid, namely isoazatrimer indene (2.38 g, 95%).

[0031] The NMR data of the obtained isoazatrimeric indene are as follows: 1 H NMR (400 MHz,d 6 -DMSO): δ 11.87 (s, 1H), 11.48 (s, 1 H), 11.38 (s, 1 H), 8.91-8.75 (m, 3 H), 7.82 (m, 3 H), 7.51-7.36 (m, 6 H).

[0032] A method for preparing fluorescent test paper for rapid detection of explosives comprises the following steps:

[0033] Weigh 0.5 g of isoazatrimer indene, 0.41 g of potassium hydroxide, and 1.34 g of epichlorohydrin, add them to a round-bottom flask, then add 10 mL of tetrahydrofuran to the round-bottom flask, and react at 80°C for 4 h. Then immerse the cut test paper for 5 min and dry it to obtain a fluorescent test paper for detecting aromatic nitro compounds. The size of the filter paper is 2 cm×2 cm.

[0034] The method for using the fluorescent test paper for rapid detection of explosives in this embodiment comprises the following steps: dripping a dichloromethane solution of trinitrotoluene (TNT) / trinitrophenol (TNP) / dinitrobenzene (DNB) with a concentration of 0.1 mol / L onto the fluorescent test paper, observing the change in the fluorescence intensity of the test paper under 365 nm ultraviolet light, and finding that the fluorescence intensity is significantly reduced ( Figure 2 ).

[0035] After software-assisted processing, the degree of fluorescence intensity reduction can be used as a basis for semi-quantitative detection of explosive concentration. The specific implementation case is as follows: the concentration is configured to be 2.18×10 -1 mol / L 1,4-dinitrobenzene solution, and the solution was diluted to a concentration of 1.09×10 -1 mol / L, 5.44×10 -2 mol / L, 2.72×10 -2 mol / L, 1.36×10 -2 mol / L, 6.80×10 -3 mol / L, 1.37×10 -3 mol / L, 2.27×10 -4 mol / L, 5.44×10 -5 mol / L, 1.09×10 -5 mol / L. Then, ten explosive detection test strips of the same specifications and prepared in the same batch were taken, and 10 μL of the above ten concentrations of 1,4-dinitrobenzene solution was added respectively. The strips were placed under 365 nm ultraviolet light, and the fluorescence quenching was recorded by taking photos. The photos were opened with Image J software and the original images were converted into grayscale images ( Figure 3) and read the grayscale value. -1 mol / L) as the independent variable, and the corresponding gray value as the dependent variable to fit, and a standard working curve with good linearity was obtained ( Figure 4 ), which can be used for semi-quantitative detection of explosive concentration, with a detection limit of 1.09×10 -5 mol / L.

[0036] The experimental results show that the test paper responds to ng-level explosives with a response time of less than 5 s, and has a good response to various aromatic nitro explosives.

[0037] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene, characterized in that: The test paper body is loaded with isoazatrimeric indene, which is connected to the cellulose macromolecule in the test paper through a covalent bond; the structural formula of the isoazatrimeric indene is as follows: ； The method for preparing the fluorescent test paper comprises the following steps: 1) Add 0.3-0.6 g of isocyanate, 0.4-0.8 g of potassium hydroxide, 1.0-2.0 g of epichlorohydrin, and then add 5-15 mL of tetrahydrofuran in a dry container and react at 80°C for 1-5 h; 2) After the reaction is completed, the cut qualitative filter paper is immersed in the above-mentioned mixed solution, taken out after a period of time, and dried to obtain a fluorescent test paper for detecting explosives; When in use, the solution to be tested is dropped onto the fluorescent test paper, and the change in fluorescence intensity of the fluorescent test paper is observed under 365 nm ultraviolet light. When the solution to be tested contains aromatic nitro explosives, the fluorescence intensity will be significantly reduced.

2. The fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene according to claim 1, characterized in that: The preparation method of the isoazatrimeric indene comprises the following steps: a) Synthesis of nitrosobenzene: Add 0.5-1.1 g sodium tungstate dihydrate and 20-30 mL 30 wt% hydrogen peroxide solution into a dry container, add 20-25 mL aniline dropwise under an ice bath, add 3-5 mL 30 wt% hydrogen peroxide solution every 15 min, add twice in total, stir for 10-15 min after the aniline is added, filter and drain the reactant, wash with cold ethanol, and dry naturally to obtain a light yellow-green solid, i.e., nitrosobenzene; b) Synthesis of isoazatrimeric indene precursor: 10-16 g of indole and 10-13 g of chloroacetic acid were added to a dry container, and then 30-50 mL of dichloromethane was added to completely dissolve the reactants. 10-15 g of nitrosobenzene was weighed and dissolved in 20-35 mL of dichloromethane and placed in a constant pressure dropping funnel. The dichloromethane solution of nitrosobenzene was added dropwise to the reaction container. After the addition was completed, the mixture was reacted at room temperature for 7-14 h, filtered, and washed with dichloromethane for 3-6 times to obtain a dark green solid, i.e., isoazatrimeric indene precursor; c) Synthesis of isoazatrimer indene: Add 2.5-3 g of isoazatrimer indene precursor into a dry container, weigh 0.8-0.9 g of phenylhydrazine and dissolve it in 25-30 mL of acetonitrile, and add the acetonitrile solution of phenylhydrazine dropwise into the reaction container with constant stirring during the addition. After the addition is complete, react at room temperature for 3-6 h, filter, and wash with cold acetonitrile for 3-5 times to obtain an off-white solid, namely, isoazatrimer indene.

3. The fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene according to claim 2, characterized in that: The dropping rate of aniline in step a) is 0.3-1.5 mL / min; In step b), the drop rate of the dichloromethane solution of nitrosobenzene is 2-5 s per drop; In step c), the dropping rate of the acetonitrile solution of phenylhydrazine is 3-5 s per drop.

4. The method for preparing a fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene according to claim 1, characterized in that: The method for preparing the fluorescent test paper comprises the following steps: 1) Add 0.3-0.6 g of isocyanate, 0.4-0.8 g of potassium hydroxide, 1.0-2.0 g of epichlorohydrin, and then add 5-15 mL of tetrahydrofuran in a dry container and react at 80°C for 1-5 h; 2) After the reaction is completed, the cut qualitative filter paper is immersed in the above-mentioned mixed solution, taken out after a period of time, and dried to obtain the fluorescent test paper for detecting explosives.

5. The method for preparing a fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene according to claim 4, characterized in that: In step 2), the soaking time is 1-60 min; the size of the qualitative filter paper is 2-4 cm×3-6 cm.

6. The method for using the fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene according to claim 1, characterized in that: The solution to be tested is dropped onto the fluorescent test paper, and the change of the fluorescence intensity of the fluorescent test paper is observed under 365 nm ultraviolet light. When the solution to be tested contains aromatic nitro explosives, the fluorescence intensity will be significantly reduced.

7. The method for using the fluorescent test paper for rapid detection of explosives based on isoazatrimeric indene according to claim 6, characterized in that: The aromatic nitro explosives include one or more of trinitrotoluene, trinitrophenol and dinitrobenzene.

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