1. The molecular imprinting ratio fluorescent probe for visually detecting quintozene is characterized by being based on fluorescent materials BPDN and BPDN @ SiO₂And preparing a template molecule PCNB.

2. The molecularly imprinted ratiometric fluorescent probe of claim 1, wherein the fluorescent material BPDN has the structure shown below:

3. the molecularly imprinted ratiometric fluorescent probe of claim 1 or 2, wherein the fluorescent material BPDN is a schiff base compound, which is formed by aggregation induction and emits orange fluorescence when the volume fraction of water in the water-DMF solution used exceeds 40% during the preparation of the probe.

4. The molecularly imprinted ratiometric fluorescent probe of claim 1, wherein the BPDN @ SiO is₂The structure of (A) is that BPDN is wrapped in SiO₂In (1), green fluorescence is emitted.

5. A fluorescence test paper for visually detecting the molecular imprinting ratio of quintozene, which is obtained by adsorbing the molecular imprinting ratio probe of claim 1 onto filter paper.

6. The preparation method of the molecularly imprinted ratiometric fluorescent probe for visually detecting quintozene as claimed in any one of claims 1 to 5, characterized by comprising the following steps of mixing BPDN and BPDN @ SiO₂And mixing, adding template molecules PCNB, a cross-linking agent and an initiator, mixing and stirring uniformly, heating and reacting under a nitrogen environment to obtain a molecularly imprinted polymer, and eluting to remove PCNB to obtain the molecularly imprinted ratiometric fluorescent probe.

7. The method of claim 6, wherein the BPDN is prepared by dissolving benzidine and hydroxy-1-naphthaldehyde respectively, mixing and stirring overnight to obtain orange precipitate, washing, centrifuging, and drying.

8. The method for preparing a molecularly imprinted ratiometric fluorescent probe according to claim 6, wherein the BPDN @ SiO₂The preparation method comprises the steps of mixing BPDN and silane organic matters, and adding the mixture into a microemulsion system for reaction.

9. The method of claim 8, wherein the silane-based organic material includes vinyltriethoxysilane and 3-aminopropyltriethoxysilane.

10. The method for preparing a molecularly imprinted ratiometric fluorescent probe according to claim 8, wherein the microemulsion system is a solution obtained by dissolving a sodium sulfonate salt, including dioctyl sodium sulfosuccinate, and mixing the solution with an organic solvent and water.

Background

Pentachloronitrobenzene (PCNB) is listed as a carcinogen list as an organochlorine protective bactericide because of its toxicity, recalcitrance, disturbance of human endocrine, and the danger of being enriched in living organisms through the food chain. In the face of the harm, countries such as Europe and America adopt measures for forbidding or limiting the use of PCNB, and although PCNB is not listed in a forbidden pesticide list in China, a plurality of analysis and detection methods for PCNB in different samples are established.

In recent years, chromatography, enzyme-linked immunosorbent assay (ELISA), spectroscopy, and the like are used for detection of PCNB. For example, Li and the like establish a detection method combining QuEChERS pretreatment with GC-MS/MS, and the method is successfully applied to analyzing and detecting 84 PCBs and OCPs pesticide residues in shellfish samples; xu et al reported a competitive ELISA for detecting PCNB, and experimental results showed that the method can effectively replace the GC method for monitoring the pesticide residue PCNB in the environment. Although the methods have the advantages of high sensitivity and strong selectivity, the methods require special and expensive instruments and specialized technicians, which greatly limits the application of the methods and are not suitable for field detection.

Each detection method has advantages and disadvantages, and visual detection is the current popular research direction. The ratiometric fluorescence method has the advantages of high sensitivity, simplicity and convenience in operation, low cost, visualization and the like, and is suitable for being applied to rapid and convenience in detection of a target object. Therefore, the invention establishes a detection method based on the molecular imprinting ratio fluorescent test paper for visual detection of PCNB.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a molecular imprinting ratio fluorescent probe and a fluorescent test paper for visually detecting pentachloronitrobenzene, which provide a good fluorescent response signal based on a fluorescent material BPDN emitting orange fluorescence and a BPDN @ SiO emitting green fluorescence₂The stable reference signal is provided, the obtained molecular imprinting ratio fluorescent probe has good selectivity and higher sensitivity, and the prepared test paper has obvious visual detection effect.

The technical content of the invention is as follows:

the invention provides a molecular imprinting ratio fluorescence probe (MIRF probe) for visually detecting quintozene, which is based on the fluorescent material BPDN emitting orange fluorescence and the fluorescent material BPDN @ SiO emitting green fluorescence₂The template molecule PCNB, and the MIRF probe prepared by adopting a molecular imprinting technology;

the structure of the fluorescent material BPDN is shown as follows:

the fluorescent material BPDN is Schiff base compound 1,1'- {4,4' -biphenyldiyl bis [ imino (E) ] } bis (2-naphthol), is BPDN for short, and is formed by aggregation induction and emission of orange fluorescence when the volume fraction of water in a water-DMF solution exceeds 40% in the preparation process of a probe.

The BPDN @ SiO₂The structure of (A) is that BPDN is wrapped in SiO₂In (b), green fluorescence is emitted.

The invention also provides a molecular imprinting ratio fluorescent test paper for visually detecting the pentachloronitrobenzene, which is obtained by adsorbing the molecular imprinting ratio probe on filter paper.

The invention also provides a preparation method of the molecular imprinting ratio fluorescent probe for visually detecting the pentachloronitrobenzene, which comprises the following steps of emitting the BPDN with orange fluorescence and emitting the BPDN @ SiO with green fluorescence₂Mixing, adding template molecules PCNB, a cross-linking agent and an initiator, mixing and stirring uniformly, then heating and reacting under a nitrogen environment to obtain a molecularly imprinted polymer, and eluting to remove PCNB to obtain the molecularly imprinted ratiometric fluorescent probe;

the fluorescent material BPDN is prepared by taking benzidine and hydroxy-1-naphthaldehyde as raw materials, and has the specific operation that the benzidine and the hydroxy-1-naphthaldehyde are respectively dissolved in an organic solvent (absolute ethyl alcohol), mixed and stirredReacting overnight to obtain orange precipitate, washing, centrifuging and drying to obtain 1,1'- {4,4' -biphenyldiyl bis [ imino (E)]Bis (2-naphthol) (BPDN). The properties are as follows: BPDN when dissolved in DMF fluoresces blue, when the concentration of BPDN is from 1.0X 10^-7M is increased to 1.0X 10^-5M, maximum emission wavelength (λ) of BPDN_max) Red-shifted from 420nm to 518nm, and the fluorescence color of the solution changed from blue to green. After adding water as a poor solvent to the above system, the maximum emission wavelength of the resulting solution was red-shifted from 518nm to 560nm, and the solution emitted orange fluorescence (FIG. 4). This phenomenon can also be achieved by varying the water-DMF volume fraction ratio (fig. 5). The concentration is 1.0 × 10^-5The BPDN of M fluoresces green in DMF, corresponding to a broad absorption in the uv-vis absorption spectrum. When the water volume fraction increased to 20%, the fluorescence color of the solution changed from green to blue, with its ultraviolet absorption red-shifted. When the volume fraction of water exceeds 40%, the solution emits orange fluorescence;

the BPDN @ SiO₂The preparation method comprises the steps of mixing BPDN and silane organic matters, adding the mixture into a microemulsion system, and reacting to obtain the product, wherein the silane organic matters comprise vinyl triethoxy silane (VTES) and 3-aminopropyl triethoxy silane (APTES);

the microemulsion system is a solution obtained by dissolving sodium sulfonate and mixing the sodium sulfonate with an organic solvent (comprising n-butanol) and water, wherein the sodium sulfonate comprises dioctyl sodium sulfosuccinate (AOT);

the cross-linking agent comprises Ethylene Glycol Dimethacrylate (EGDMA);

the initiator includes Azobisisobutyronitrile (AIBN).

The invention has the following beneficial effects:

the molecular imprinting ratio fluorescent probe for detecting the quintozene is prepared based on Schiff base fluorescent material BPDN and is prepared by emitting green fluorescent BPDN @ SiO₂Providing a stable reference signal and emitting orange fluorescent BPDN providing a good fluorescent response signal; the molecular imprinting ratio fluorescent probe has good selectivity and higher sensitivity, and the probe is successfully applied toThe analysis and detection of PCNB in the soil, tap water and longan pulp samples, the prepared fluorescent test paper has obvious visual detection effect on PCNB;

the preparation of the fluorescent probe comprises the steps of firstly synthesizing a multi-color fluorescent Schiff base compound BPDN as a fluorescent material, synthesizing a reference signal material emitting green fluorescence and a response signal material emitting orange fluorescence on the basis, then preparing the MIRF fluorescent probe by combining a molecular imprinting technology, adsorbing the molecular imprinting ratio fluorescent probe on filter paper to construct MIRF test paper, applying the MIRF test paper to visual detection of pesticide residue PCNB, and enabling the fluorescent color of the test paper to change along with the increase of the concentration of template molecules to realize visual detection.

Drawings

FIG. 1 is a flow chart of the preparation of the molecular imprinting ratio fluorescent probe and the detection test paper thereof of the present invention;

FIG. 2 is a synthesis scheme of the fluorescent material BPDN of the present invention;

FIG. 3 is an infrared spectrum of fluorescent material BPDN;

FIG. 4 is a fluorescence emission spectrum of fluorescent material BPDN;

FIG. 5 is a graph of fluorescence emission spectrum and UV-VIS absorption spectrum of fluorescent material BPDN in different mixed solvents;

FIG. 6 shows BPDN @ SiO of the present invention₂(A) SEM images of MIRF probe (B) and non-molecularly imprinted ratiometric fluorescent probe (NIRF probe) (C);

FIG. 7 shows MIRF probe, BPDN and BPDN @ SiO of the present invention₂The fluorescence emission spectrum and the visualization graph;

FIG. 8 is a graph of the fluorescence emission spectrum and linear plot of PCNB detected by the MIRF probe and the NIRF probe of the present invention;

FIG. 9 is a graph showing the results of stability examination at room temperature of MIRF probe solutions, MIRF probe and PCNB mixed solutions according to the present invention;

FIG. 10 is a graph of the fluorescence emission spectra of the MIRF probe of the present invention detecting PCB, PCBCN and PCBA;

FIG. 11 is a graph of the MIRF probe solution, MIRF probe and PCNB mixture solution anti-ion interference of the present invention;

FIG. 12 is a visual depiction of the detection of PCNB in MIRF fluorescence test strips of the present invention in sunlight (a) and under UV light (b).

Detailed Description

The present invention is described in further detail in the following detailed description with reference to specific examples, which are intended to be illustrative only and not to be limiting of the scope of the invention, as various equivalent modifications of the invention will become apparent to those skilled in the art after reading the present invention and are intended to be included within the scope of the appended claims.

All the raw materials and reagents of the invention are conventional market raw materials and reagents unless otherwise specified.

Example 1

Preparation of fluorescent material BPDN:

weighing 0.64g of benzidine (3.5mmol), placing the benzidine in a round-bottom flask, adding 30mL of absolute ethyl alcohol, and stirring to dissolve the benzidine; 1.20g of 2-hydroxy-1-naphthaldehyde (7.0mmol) was dissolved in 30mL of anhydrous ethanol and added dropwise to the round-bottomed flask. The mixed solution was then stirred to react overnight, giving an orange precipitate. The product was washed 3 times with absolute ethanol, centrifuged at 4000r for 5min and dried in an oven at 60 ℃ to yield 1.40g of BPDN (82.4% yield). 0.0050g BPDN (0.01mmol) was weighed and dissolved in 10.0mL N, N-Dimethylformamide (DMF) to give a stock solution of BPDN (1.0 mM);

the synthetic route of the BPDN 1,1'- {4,4' -biphenyldiylbis [ imino (E) ] } bis (2-naphthol) is shown in FIG. 2.

As shown in FIG. 3, it is an infrared spectrum of BPDN material, from which characteristic absorption peak (-C ═ N, 1623 cm) of Schiff base can be seen^-1) It shows that the Schiff base compound BPDN is successfully synthesized.

As shown in FIG. 4, the inset is from left to right 0.10. mu.M BPDN in DMF, 10.0. mu.M BPDN in DMF and 10.0. mu.M BPDN at 40% H₂Visualization of O-DMF mixed solvent, in which BPDN dissolved in DMF emits blue fluorescence. When the concentration of BPDN is from 1.0X 10^-7M is increased to 1.0X 10^-5M, the maximum emission wavelength of BPDN is red-shifted from 420nm to 518nm, and of solutionThe fluorescent color also changes from blue to green. After adding poor solvent water into the system, the maximum emission wavelength of the obtained solution is red shifted from 518nm to 560nm, and the solution emits orange fluorescence.

As shown in FIG. 5, the concentration in graph A is 1.0X 10^-5BPDN of M fluoresces green in DMF, corresponding to a broad absorption in the uv-vis absorption spectrum (panel B). As can be seen from the graphs A-B, when the water volume fraction is increased to 20%, the fluorescence color of the solution changes from green to blue, with a red-shift in the UV absorption. When the volume fraction of water exceeds 40%, the solution fluoresces orange, and the intensity of the fluorescence becomes weaker as the volume fraction of water increases, and the ultraviolet absorption of the solution is red-shifted and then substantially unchanged. This is because the excimer formation causes the maximum fluorescence emission wavelength of BPDN to red shift from 516nm to 560 nm; in addition, the formation of J-aggregate causes red shift of BPDN due to ultraviolet absorption, and then molecules in the solution can aggregate to generate precipitation along with the increase of the concentration of BPDN or after poor solvent water is added, so that the fluorescence intensity is reduced. In FIG. C, the concentration is 1.0X 10^-5The BPDN of M has a maximum emission wavelength in MeOH of 516nm, corresponding to a narrower absorption in the uv-vis absorption spectrum (panel D). As can be seen from FIGS. C-D, when the water volume fraction is increased to 20%, the maximum fluorescence emission wavelength of BPDN is red-shifted from 516nm to 560nm, with its UV absorption blue-shifted; the fluorescence intensity of the water becomes weaker and weaker along with the increase of the volume fraction of the water, and the ultraviolet absorption of the solution of the water is blue-shifted and then basically unchanged. This is because the excimer formation results in a red-shift of the maximum fluorescence emission wavelength of BPDN from 516nm to 560 nm; furthermore, the UV absorption of BPDN is blue-shifted due to the formation of H-aggregates, and then as the volume fraction of water increases, the molecules in the solution collect to precipitate, resulting in a decrease in fluorescence intensity. In FIG. E, the concentration is 1.0X 10^-5The BPDN of M has a maximum emission wavelength of 510nm in THF, corresponding to a broad absorption in the uv-vis absorption spectrum (fig. F). As can be seen from FIGS. E-F, the maximum fluorescence emission wavelength of BPDN was red-shifted from 510nm to 516nm, purple-shifted when the volume fraction of water was increased to 20%Absorbing externally to generate red shift; when the volume fraction of water exceeds 60%, the maximum fluorescence emission wavelength of BPDN is red-shifted from 516nm to 560nm, and the ultraviolet absorption of BPDN is blue-shifted; the fluorescence intensity of the water is firstly enhanced and then weakened along with the increase of the volume fraction of the water, and simultaneously, the ultraviolet absorption of the solution of the water is blue-shifted and then basically has no change. This is because the excimer formation leads to a red-shift of the maximum fluorescence emission wavelength of BPDN from 510nm to 516nm, and furthermore, the formation of J-aggregates leads to a red-shift of the uv absorption of BPDN; then as the volume fraction of water increases by 60%, the formation of another excimer causes a red-shift of the maximum fluorescence emission wavelength of BPDN from 516nm to 560nm, and furthermore the uv absorption of BPDN is blue-shifted due to the formation of H-aggregates; then, as the volume fraction of water increases, molecules in the solution aggregate to precipitate, resulting in a decrease in fluorescence intensity.

Example 2

Green fluorescent signal material BPDN @ SiO₂：

0.44g of AOT (sodium dioctyl sulfosuccinate) was weighed into 20mL of deionized water, and 800.0. mu.L of n-butanol was added and stirred until the solution was clear and transparent to form a microemulsion system, followed by the addition of 800.0. mu.L of LBPDN stock solution (1.0mM) and 200.0. mu.L of LVTES (vinyltriethoxy silane).

After stirring for 4 hours, 10.0. mu.L of LAPTES (3-aminopropyltriethoxysilane) was added and the reaction was further stirred for 24 hours. After the reaction is finished, adding absolute ethyl alcohol to demulsify, standing to remove supernatant, washing and precipitating the precipitate for 3 times respectively with acetone and water, centrifuging for 5min at 4000r, and drying in an oven at 60 ℃ to obtain a reference signal material BPDN @ SiO emitting green fluorescence₂。

Example 3

An orange fluorescent signal material BPDN:

10mg of BPDN (0.02mmol) was weighed out and dissolved in 10.0mL of N, N-Dimethylformamide (DMF) to give a BPDN stock (2.0mM), and 4.0mL of BPDN stock (2.0mM) was added to DMF-water solution (v/v 4:3, 7.0mL) to generate aggregation-induced luminescence, giving a response signal material BPDN which emits orange fluorescence.

Example 4

Preparation of a molecularly imprinted ratiometric fluorescent MIRF probe:

weighing the reference signal material BPDN @ SiO of example 2₂60.0 mg of a solution of BPDN (2.0mM) from example 3 dispersed in 4:3 (v/v) DMF in water (7.0mL) was added and stirred for 10min to obtain a response signal material, followed by addition of 0.075 mmol of template molecule PCNB, 1.5mmol of crosslinker EGDMA and 10.0mg of initiator AIBN and stirring at room temperature for 12h to form a self-assembling solution.

Introducing high-purity nitrogen for 10min, placing the mixture in a water bath kettle at 60 ℃ for reaction for 6h to generate a molecularly imprinted polymer, and finally washing the product with cyclohexane for several times to elute PCNB until the absorption peak of PCNB cannot be detected by the eluate with an ultraviolet-visible spectrophotometer, thus obtaining the MIRF probe.

As shown in figure 1, the preparation process of the molecular imprinting ratio fluorescent probe and the detection test paper thereof of the invention is shown in the figure, multicolor fluorescence Schiff base compound BPDN directly synthesized by Schiff base reaction is taken as fluorescent material, and reference signal material BPDN @ SiO which emits green fluorescence is respectively synthesized on the basis of the fluorescent material₂And a response signal material BPDN emitting orange fluorescence, an MIRF fluorescent probe is prepared by combining a molecular imprinting technology, the MIRF fluorescent probe is adsorbed on filter paper to prepare MIRF test paper, the test paper is successfully used for visually detecting PCNB, and the fluorescence color of the obtained test paper changes along with the increase of the concentration of template molecules, so that visual detection is realized.

Non-molecularly imprinted ratiometric fluorescent NIRF probes were synthesized under the same conditions, but without the addition of the template molecule PCNB during the preparation.

As shown in FIG. 6, BPDN @ SiO was separately aligned using SEM₂MIRF and NIRF probes, and FIG. 6A, it can be seen that the synthesized silica nanoparticles are all spherical and BPDN @ SiO₂Has a particle size of about 60nm, and is shown in FIG. 7 where BPDN @ SiO corresponds₂The maximum emission wavelength is at 440nm, and BPDN can be successfully embedded in the silicon dioxide nano-particles;

in FIGS. 6B-C, the surface roughness of the MIRF probe can be seen, while the NIRF probe is relatively smooth, indicating that the template is relatively smoothThe imprinting aperture of molecular PCNB has been successfully imprinted in MIRF probes. In addition, the fluorescence emission spectra of the MIRF probe (FIG. 7) shows that it has dual emission peaks at 440nm and 516nm, indicating a green fluorescent emitting BPDN @ SiO₂And BPDN emitting orange fluorescence were both successfully encapsulated in molecularly imprinted polymers, indicating successful preparation of the MIRF probe.

Test examples

Fluorescence detection and visualization detection of PCNB

Using fluorescence emission spectra and UV lamps (lambda)_ex365nm) investigated the analytical performance of the MIRF probe.

As shown in FIG. 8, the fluorescence intensity ratio of the MIRF probe prepared in example 4 and the PCNB concentration are in a linear relationship of 50.0-600.0. mu. mol/L, and the linear equation obtained by fitting is F₅₁₆/F₄₄₀＝-0.00155×[PCNB/μM]+1.785(R ═ 0.9984), the limit of detection was calculated to be 14.7 μ M according to the 3 σ/k rule.

In the inset of fig. 8A, the fluorescence color of the MIRF probe solution gradually changed from orange to yellow and finally to green, indicating that it has the potential for visual detection in the field. The backsight non-molecularly imprinted ratiometric fluorescent probe (NIRF probe), as can be seen from fig. 8B, the PCNB has a low quenching efficiency on the NIRF probe, and the fluorescence color change is also not obvious, and is substantially orange, indicating that the MIRF probe has a much stronger selective recognition capability on the PCNB than the NIRF probe, indicating that the MIRF probe has a good specific recognition capability compared to the NIRF probe.

2. Repeatability and stability of fluorescent probe MIRF

The concentration of the fluorescent probe was selected to be 2.0mg/mL and the concentration of PCNB was 300.0. mu.M, and the ratio of the fluorescence intensity of the solution F was recorded₅₁₆/F₄₄₀。

The repeatability of the MIRF probe is checked by measuring 6 mixed solutions of different MIRF probes and PCNB, and the fluorescence intensity ratio F is obtained after 3 times of repeated measurement of each sample₅₁₆/F₄₄₀The Relative Standard Deviation (RSD) difference was 1.5%.

To investigate its stability, the fluorescence intensity ratio F of the MIRF probe solution at room temperature was investigated₅₁₆/F₄₄₀All are the same asThe fluorescence intensity ratio F of the mixed solution of the MIRF probe and the PCNB at room temperature was also examined₅₁₆/F₄₄₀As shown in FIG. 9, the MIRF probe solution, the mixed solution of MIRF probe and PCNB, was stable for 2 hours.

The results show that the fluorescent probe and the application thereof have good repeatability and stability.

3. Selectivity and interference rejection of fluorescent probe MIRF

The MIRF concentration of the fluorescent probe is selected to be 2.0mg/mL, the influence of PCNB structural analogs (PCB, PCBA and PCBCN) and metal ions on the measurement of the PCNB is examined, and the fluorescence emission spectrum of each structural analog solution is recorded.

Under the best experimental conditions, the selectivity of the PCNB structural analogue is examined by adding the same concentration of the structural analogue respectively, and the measurement result is shown in FIG. 10, so that the PCNB structural analogue has very low fluorescence quenching efficiency and no obvious color change (basically orange) is observed under the irradiation of an ultraviolet lamp. The results show that the structural analogs do not influence the analysis and detection of the MIRF probe on PCNB, and the MIRF probe prepared by the invention has good selectivity.

The effect of interfering substances on the measurement of PCNB was also investigated by adding an excess of metal ions, with a probe concentration of 2.0mg/mL and a PCNB concentration of 300.0. mu.M, and recording the fluorescence intensity ratio F of the solution₅₁₆/F₄₄₀. The measurement results are shown in FIG. 11. The MIRF probe solution and the mixed solution of the MIRF probe and the PCNB have respective fluorescence intensity ratios F in the presence of excessive metal ions compared with the respective blanks₅₁₆/F₄₄₀No significant change occurred, indicating that the MIRF probe did not respond to metal ions and therefore the fluorescence intensity ratio of the solution was F₅₁₆/F₄₄₀The MIRF probe is not interfered by metal ions, and the result shows that the MIRF probe has good anti-interference capability.

4. Reagent sample detection of fluorescent probe MIRF

The results of the PCNB measurement using the fluorescent probe MIRF applied to tap water, soil and longan pulp samples are shown in table 1:

TABLE 1 normalized recovery of PCNB in tap water, soil and longan pulp samples

The adding standard recovery rate of the fluorescence detection method is between 99.7% and 111.3%, the Relative Standard Deviation (RSD) obtained by calculation is less than 3.0% after 3 times of parallel detection, and the method is a reliable method for determining the PCNB of the actual sample.

The probe concentration was chosen to be 2.0mg/mL, the PCNB concentration was 300.0. mu.M, and the fluorescence intensity ratio F of the solution was recorded₅₁₆/F₄₄₀. Under the best experimental conditions, the precision of the MIRF probe and the PCNB is studied by measuring the mixed solution of the MIRF probe and the PCNB, and the fluorescence intensity ratio F is obtained after 6 times of repeated measurement₅₁₆/F₄₄₀The relative standard deviation of the fluorescence probe MIRF is 1.6 percent, which shows that the detection method of the fluorescence probe MIRF has good accuracy and precision.

5. Test paper application of fluorescent probe MIRF

The 100.0 μ L MIRF probe solution was adsorbed on filter paper and dried at room temperature to prepare MIRF test paper, which was placed under an ultraviolet lamp (. lamda.) (Lambda.)_ex365nm) shows orange fluorescence under irradiation. PCNB (100.0-600.0 mu M) with different concentrations is dripped on a series of test paper for visual detection.

The fluorescence color of each test paper was photographed in a dark environment and under ultraviolet light. From FIG. 12, it can be observed that the test paper has a fluorescence color change from orange to yellow to green under UV irradiation after adding PCNB with different concentrations, indicating that the prepared test paper is feasible for visually detecting PCNB.