A fluorescent colorimetric ionic liquid, a composite ionic probe and application in detection of phoxim

Abstract

The application discloses a fluorescent colorimetric ionic liquid, a composite ionic probe and application in detection of phoxim, and the functionalized composite ionic probe is successfully synthesized by electrostatic self-assembly of the fluorescent colorimetric ionic liquid and a surfactant, the sensitivity and selectivity of the composite ionic probe in detection of phoxim are effectively improved, and the detection limit is reduced, and the detection limit of the fluorescent method in detection of phoxim can reach 3.0*10 ‑8 M, which is lower than the minimum maximum allowable concentration specified in the national standard. The composite ionic probe can visually and conveniently detect phoxim.

Description

(I) TECHNICAL FIELD

[0001] The present application relates to a fluorescent colorimetric ionic liquid, a composite ionic probe and its application in the detection of phoxim. (II) BACKGROUND

[0002] Phoxim, an organophosphorus insecticide, is commonly used for parasitic and pest control in crops. However, the abuse of phoxim can lead to its gradual accumulation in the food chain and natural environment, seriously endangering human health. Phoxim has irreversible neurotoxicity, which can cause severe clinical symptoms such as vomiting, coma, and even death. In order to ensure food safety, China has adopted very strict legal regulations to control its residues. In the national food safety standard (GB 2763-2021), the maximum allowable concentration of phoxim in cereal vegetables should be less than 0.05 mg / kg, and the maximum allowable concentration of phoxim in tea should be less than 0.2 mg / kg. The existing pesticide residue detection methods mainly include enzyme inhibition reaction detection, immune reaction detection, chromatography-mass spectrometry technology, biosensor, chemical optical detection, etc. At present, the most commonly used is still the chromatography-mass spectrometry technology based on large instruments, which usually shows high accuracy and sensitivity, but needs to be carried out in professional laboratories and requires professional personnel to operate and maintain. Therefore, it is imperative to propose a simple, rapid and suitable detection method for on-site analysis.

[0003] Optical probes have great potential in the detection of harmful substances due to their high sensitivity, fast response speed, and simple operation. Fluorescent organic materials, as common optical probe materials, have limited light physical signal transduction of functionalized fluorophores due to various environmental factors such as solvent, pH, and concentration, which reduces their sensitivity. In addition, they have poor solubility in water. This requires an intelligent sensing method that amplifies the fluorescent response to analytes in aqueous solution. Micelle-based probes are considered promising candidates for chemical sensors, and surfactants are one of the effective methods to improve the solubility of organic materials in water. Ionic liquids (ILs) are functional materials composed of only anions and cations. The high tunability allows the introduction of fluorescent organic materials as signal modules. In addition, their ionic properties promote the electrostatic self-assembly process and form ion associates with ionic surfactants such as cetyltrimethylammonium bromide (CTAB). CTAB can provide a positively charged surface environment and a hydrophobic internal micro-heterogeneous phase environment, allowing poorly soluble probes in water to have good solubility and high fluorescence emission intensity in water. Therefore, based on the electrostatic assembly technology, it is possible to develop a composite ionic probe formed by self-assembly of surfactants and ionic liquids, and use the probe for sensitive detection of phoxim. (III) SUMMARY

[0004] The application aims to provide a fluorescent colorimetric ionic liquid, a composite ionic probe and application in detection of phoxim, adopt a double-path strategy of electrostatic and hydrophobic between the probe and phoxim, construct a new composite ionic probe (DCFP@CTAB) formed by electrostatic self-assembly of ionic liquid and surfactant, the ionic liquid is encapsulated into the hydrophobic core of CTAB, the solubility problem of hydrophobic ionic liquid in water and fluorescence quenching is improved by surfactant; the probe has the advantages of high sensitivity, good specificity and visual signal. The paper-based developed at the same time can meet the needs of portable devices, and can be applied to detection of phoxim in various real samples, and provides a new idea for convenient detection of phoxim in complex matrix.

[0005] The technical scheme adopted by the application is:

[0006] The application provides a fluorescent colorimetric ionic liquid, the chemical formula is [DCF][P 66614 ]2, and the structural formula is shown as formula (I):

[0007]

[0008] The application further provides a synthesis method of the fluorescent colorimetric ionic liquid, and the method is:

[0009] [P 66614 ][OH] and 2',7'-dichlorofluorescein are dissolved in anhydrous ethanol, stirring reaction is carried out at 30-80 DEG C for 4-16 h (preferably 60 DEG C for 12 h), after the reaction is completed, the solvent is removed by evaporation under reduced pressure, and the product is further dried at 60-100 DEG C in a nitrogen atmosphere to remove trace amounts of ethanol and water in the product, so that the fluorescent colorimetric ionic liquid is obtained; the molar ratio of [P 66614 ][OH] to 2',7'-dichlorofluorescein is 1-3:1 (preferably 2:1).

[0010] [P 66614 ][OH] is obtained by dechlorination treatment of trihexyl (tetradecyl) phosphonium chloride ([P 66614 ][Cl]) through a strong basic anion exchange resin, and the dechlorination method is as follows: the ethanol solution of [P 66614 ][Cl] is added to a chromatography column containing a strong basic anion exchange resin (preferably 717 strong basic anion exchange resin), the eluate is collected by slowly flushing with anhydrous ethanol, and [P 66614 ][OH] is obtained.

[0011] The application further provides a composite ion probe, which is prepared by slowly adding drop by drop an ethanol solution of the fluorescent colorimetric ionic liquid shown in formula (I) into an aqueous CTAB solution, and obtaining a static self-organizing composite ion probe solution, denoted as DCFP@CTAB solution, after sufficient stirring at room temperature.

[0012] The CTAB has a chemical formula of C 19 H 42 BrN, and a structural formula as shown in formula (II):

[0013]

[0014] Further, the concentration of the ionic liquid ethanol solution is 0.1-1 mM (preferably 0.1 mM), the concentration of the aqueous CTAB solution is 1-5 mM (preferably 3 mM), and the volume ratio of the ionic liquid ethanol solution to the aqueous CTAB solution is 1:10-20 (preferably 1:12.5).

[0015] The application further provides an application of the composite ion probe in detection of an actual sample of phoxim.

[0016] Further, the method of the application is as follows: after grinding and crushing a solid actual sample to be detected, ethanol is used as an extraction agent to ultrasonically extract the sample under the condition of 100-300 W (preferably 250 W) for 5-20 min (preferably 15 min), and then centrifuged to collect the supernatant; the composite ion probe is added into the supernatant or a liquid actual sample to be detected, and the fluorescence spectrum at 510-650 nm is detected to obtain the content of phoxim in the actual sample to be detected according to a standard curve between the fluorescence intensity quenching value (ΔF) at 538 nm and the concentration of phoxim.

[0017] Further, the volume of the ethanol is 5-20 mL / g (preferably 10 mL / g) based on the mass of the solid actual sample to be detected; and the concentration of the composite ion probe added into the supernatant or the liquid actual sample to be detected is 1-80 µM (preferably 40 µM).

[0018] Further, the standard curve between the fluorescence intensity quenching value (Delta F) at 538nm and the concentration of phoxim is drawn as follows: 100ul of 80uM complex ion probe solution and different volumes of phoxim aqueous solution are added into a centrifuge tube, then pure water is added to 1.0ml, so that the probe concentration is 8uM, the final concentration of phoxim is 0.0, 0.05, 0.07, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 2.0, 3.0, 5.0, 7.0, 9.0, 10.0uM respectively, after mixing evenly, pour into a quartz cuvette, measure the fluorescence spectrum of 510-650nm, take the fluorescence intensity quenching value (Delta F=F0-F) at 538nm as the ordinate, and take the concentration of phoxim as the abscissa to draw the standard curve.

[0019] Further, the solid actual sample to be tested includes tea leaves, soil, baby bok choy, corn, cucumber or rice; the liquid actual sample to be tested includes river water, tap water.

[0020] The application further provides a test strip for rapidly visualizing and detecting phoxim prepared from the complex ion probe, which is prepared by the following steps: after the filter paper strip is soaked in the complex ion probe ethanol solution (preferably 80uM) and naturally dried, a test strip is prepared;

[0021] The application method of the test strip is as follows: the solution to be tested is added dropwise to the test strip, and the test strip is placed at room temperature for 5min, then dried, and the fluorescence color of the test strip is recorded under a 365nm ultraviolet lamp; the content of phoxim in the sample to be tested is preliminarily judged by taking the test strip fluorescence quenching standard card as a reference, the gray value of the test strip is extracted, and the content of phoxim in the sample to be tested is further determined according to the standard curve drawn between the gray value change and the logarithmic value of the concentration of phoxim; the test strip fluorescence quenching standard card is prepared by adding phoxim ethanol solution dropwise to the test strip, placing at room temperature for 5min, then drying, and recording the fluorescence color of the test strip under a 365nm ultraviolet lamp. The concentration of the phoxim ethanol solution is 0, 0.1, 1, 5, 7, 10, 30, 50, 70, 100, 300, 500, 700, 1000uM. The fluorescence color of the test strip gradually changes from bright yellow-green fluorescence to dark fluorescence.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] (1) The fluorescent colorimetric ionic liquid has bright fluorescence color, high sensitivity and good chemical stability, and is an excellent luminescent material, which serves as a signal reporting unit.

[0024] (2)The present application synthesizes a functionalized composite ion probe DCFP@CTAB by electrostatic self-assembly of fluorescent colorimetric ionic liquid and surfactant. The hydrophobic ionic liquid is encapsulated into the hydrophobic core of CTAB, and the positive corona and hydrophobic inner cavity around CTAB are used as the adsorption unit of phoxim. The positively charged hydrophilic corona preferentially approaches phoxim by electrostatic attraction, and the phoxim enriched in the corona can further diffuse into the fluorescent core. The "electrostatic and hydrophobic" dual-path strategy between the probe and phoxim not only improves the poor solubility of ionic liquid in water and the fluorescence quenching problem, but also effectively improves the sensitivity and selectivity of the composite ion probe for detecting phoxim, and reduces the detection limit. The detection limit of DCFP@CTAB for phoxim fluorescence detection can reach 3.0 x 10 -8 M, which is lower than the minimum maximum allowable concentration specified in the national standard.

[0025] (3) The composite ion of the present application realizes the fluorescence quantitative detection of phoxim in a wide linear range, and the linear range is 0.05-1 μM. The composite ion can identify phoxim from 20 different pesticides, and has good sensitivity, selectivity and anti-interference.

[0026] (4) The composite ion probe of the present application can visually and conveniently detect phoxim. The DCFP@CTAB is loaded on filter paper to make a portable test paper strip for colorimetric quantitative detection of phoxim. After adding phoxim, the green fluorescence of the DCFP@CTAB probe is obviously quenched. At the same time, the probe solution can show a multi-color change from green, orange to pink purple, and the colorimetric detection limit is as low as 1.7 x 10 -7 M.

[0027] (5) The composite ion probe of the present application shows high sensitivity and specificity to phoxim, realizes fluorescence and colorimetric quantitative detection of phoxim in a wide linear range, and exhibits a multi-color change visible to the naked eye. The composite ion probe of the present application can be assembled into a portable paper-based device to realize rapid, on-site semi-quantitative detection of phoxim. The present application can qualitatively analyze and quantitatively detect phoxim residues in real samples, and provides a sensitive and visual detection method for organic phosphorus pesticide residue detection. (Four)DETAILED DESCRIPTION

[0028] Figure 1 Zeta potential of [DCF][P 66614 ]2 and DCFP@CTAB in aqueous solution (a); morphology of DCFP@CTAB under electron transmission electron microscope (b).

[0029] Figure 2 Fluorescence emission spectrum of DCFP@CTAB under different concentrations of phoxim.

[0030] Figure 3 The graph of the fluorescence quenching intensity (ΔF) of DCFP@CTAB at 538 nm versus the concentration of phoxim (a) and the linear calibration curve of the fluorescence quenching intensity versus the concentration of phoxim (b) at different concentrations of phoxim.

[0031] Figure 4 The structural formula and number of phoxim and 19 interfering pesticides detected by the DCFP@CTAB probe.

[0032] Figure 5 The fluorescence spectrum and fluorescence quenching intensity of different pesticides detected by DCFP@CTAB: a represents the fluorescence spectrum of different pesticides detected by DCFP@CTAB; b represents the fluorescence spectrum of DCFP@CTAB when coexisting with phoxim and interfering pesticides; c represents the fluorescence quenching intensity column chart of different pesticides detected by DCFP@CTAB; d represents the fluorescence quenching intensity column chart of DCFP@CTAB when coexisting with phoxim and interfering pesticides.

[0033] Figure 6 The fluorescence visualization photos (A) and colorimetric photos (B) of DCFP@CTAB mixed with 0-30 μM phoxim under 365 nm ultraviolet light.

[0034] Figure 7 The linear calibration curve (a) of the color parameter (R / G) of DCFP@CTAB mixed with different concentrations of phoxim versus the concentration of phoxim and its local enlarged view (b).

[0035] Figure 8 The fluorescence photos of the test strip based on DCFP@CTAB after adding different concentrations of phoxim (0-1000 μM) under 365 nm ultraviolet light.

[0036] Figure 9 The graph of the gray scale change value (ΔGray) of the test strip image based on DCFP@CTAB after adding different concentrations of phoxim versus the concentration of phoxim (a) and the linear calibration curve of the gray scale change value versus the logarithm of the concentration of phoxim (b). (V) SPECIFIC EMBODIMENTS

[0037] The application will be further described in conjunction with specific embodiments, but the protection scope of the application is not limited to this:

[0038] The chemical reagents and solvents used in the examples are commercially available and are of analytical purity.

[0039] The fluorescence spectrum determination conditions are set as follows: the excitation wavelength is 508 nm, the emission wavelength is 510-650 nm, and the excitation and emission slit widths are 2.5 nm and 5 nm, respectively.

[0040] Example 1, synthesis of fluorescent colorimetric ionic liquid [DCF][P 66614 ]2, synthesis of composite ionic probe

[0041] (1) Dechlorination of [P 66614 ][Cl]:

[0042] 40 g of [P 66614 ][Cl] liquid was added to a chromatographic column filled with 717 strong basic anion exchange resin ([P 66614 ][Cl] and strong basic anion exchange resin mass ratio was 1:6), and slowly washed with anhydrous ethanol until the effluent was neutral. The basic effluent was collected to obtain 120 mL of [P 66614 ][OH] ethanol solution containing 20.60 g, and its concentration was determined by titration to be 0.3430 M.

[0043] (2) Synthesis of fluorescent colorimetric ionic liquid [DCF][P 66614 ]2:

[0044] 5.83 mL of [P 66614 ][OH] ethanol solution (containing 1.0010 g of [P 66614 ][OH]) obtained in step (1) and 0.4012 g of 2',7'-dichlorofluorescein were added to a round-bottom flask in a molar ratio of 2:1, and an appropriate amount of anhydrous ethanol was added for dissolution. The reaction was carried out at 60°C under oil bath stirring for 12 h. After removing the solvent ethanol from the product after the reaction using a rotary evaporator, the product was further heated at 80°C under nitrogen atmosphere to remove trace amounts of ethanol and water in the product, obtaining 1.1668 g of brown-red viscous liquid, which was the fluorescent colorimetric ionic liquid [DCF][P 66614 ]2. It can be stored in a sealed manner at room temperature. The ionic liquid [DCF][P 66614 ]2 was prepared into an 80 μM solution with water, and the Zeta potential was detected, the results are shown in Figure 1 a.

[0045] (3) The ionic liquid [DCF][P 66614 ]2 prepared in step (2) was prepared into an ionic liquid mother liquor (0.1 mM), and 320 μL of the mother liquor was slowly added dropwise to 40 mL of CTAB aqueous solution (3.0 mM). After fully stirring at room temperature, an 80 μM composite ionic probe solution was obtained, which was recorded as DCFP@CTAB solution. The Zeta potential of the obtained 80 μM DCFP@CTAB solution was detected, and the results are shown in Figure 1 a, and the electron transmission electron microscopy image is shown in Figure 1 b.

[0046] As shown in Figure 1As shown, the self-assembly between the ionic liquid and CTAB was proved by the change of Zeta potential; the formed probe presented uniform spherical shape by the electron transmission electron microscopy image.

[0047] Example 2, sensitive and visual detection of phoxim in real samples by using the composite ionic probe

[0048] The DCFP@CTAB solution (80 μM) prepared by the method of Example 1 was subjected to the following detection:

[0049] (1) The fluorescence detection limit of DCFP@CTAB probe for phoxim:

[0050] Phoxim was accurately weighed and dissolved in ethanol to prepare a stock solution of 0.1 mM. During the fluorescence detection, 100 μL of DCFP@CTAB solution (80 μM) and different volumes of phoxim stock solution were added into a centrifuge tube, and then diluted with pure water to 1.0 mL, so that the final concentration of phoxim was 0.0, 0.05, 0.07, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 2.0, 3.0, 5.0, 7.0, 9.0, 10.0 μM, respectively. After mixing, the mixture was poured into a quartz cuvette, and the fluorescence spectrum of 510-650 nm was measured. Figure 2 As shown, the fluorescence intensity of the probe at 538 nm gradually decreased.

[0051] The curve graph with the fluorescence quenching intensity at 538 nm as the vertical coordinate and the concentration of phoxim (0-10 μM) as the horizontal coordinate is shown in FIG. 2a. Figure 3 The linear calibration curve of fluorescence quenching intensity and phoxim concentration (0-1.0 μM) is shown in FIG. 2b. Figure 3 The linear correlation equation fitting is ΔF = 1335.7C + 47.1 (R 2 = 0.9920), and the detection limit LOD is 3.0 x 10 -8 M according to the three times signal-to-noise ratio (3σ / k). The fluorescence quenching intensity (ΔF = F0-F) of the emission peak at 538 nm showed a good linear relationship with the concentration of phoxim in the range of 0.05-1 μM.

[0052] (2) The selectivity and anti-interference of DCFP@CTAB probe for phoxim detection:

[0053] Pesticides and numbers: 1 phoxim, 2 bensulfuron methyl, 3 carbendazim, 4 cyfluthrin, 5 dimethoate, 6 beta-cypermethrin, 7 quintozene, 8 paraquat, 9 deltamethrin, 10 parathion methyl, 11 chlorpyrifos, 12 fomesafen, 13 triazophos, 14 pretilachlor, 15 acephate, 16 diazinon, 17 machette, 18 acetochlor, 19 profenfos and 20 dichlorvos, the structural formula is shown in Figure 4

[0054] In 100 μL, 80 μM DCFP@CTAB solution, each type of pesticide was added alone, and then pure water was added to 1.0 mL, and the final concentration of each type of pesticide was 5.0 μM. The control (curve 0 in a) was not added with pesticides. The fluorescence spectrum of 510-650 nm (a) was detected, and the fluorescence quenching intensity (ΔF) at 538 nm was taken as the vertical coordinate, and the type of pesticide was taken as the horizontal coordinate to draw a column chart (c), which proved that the probe had excellent selectivity. Figure 4 Figure 5 Figure 5 Figure 5

[0055] In addition, in 100 μL, 80 μM DCFP@CTAB solution, 5.0 μM phoxim and equivalent other interfering pesticides (pesticides 2-20 in b) were added at the same time, and then pure water was added to 1.0 mL, and the final concentration of each type of interfering pesticide was 5.0 μM. The control (curve 0 in b) was not added with pesticides. The fluorescence spectrum was recorded in the same way, and the column chart was drawn, as shown in b and d in 5, which proved that the probe had good anti-interference performance. Figure 4 Figure 5 Figure 5

[0056] (3) Visual detection of DCFP@CTAB probe for phoxim:

[0057] ​​​​​​​​Into centrifuge tubes, 250 μL of 80 μM DCFP@CTAB solution and different volumes of phoxim stock solution were added, and then diluted to 1.0 mL with pure water, so that the final concentration of phoxim was 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 3.0, 5.0, 7.0, 9.0, 10, 30 μM, and the concentration of DCFP@CTAB was 20 μM. Photographs were taken under 365 nm UV light and sunlight, respectively.

[0058] As shown in Fig. 1A, under 365 nm UV light irradiation, the bright green fluorescence of DCFP@CTAB solution was clearly observed to be quenched by phoxim, indicating that DCFP@CTAB has excellent fluorescence visualization. Figure 6 As shown in Fig. 1B, under sunlight, the naked eye observed that the solution exhibited a wide color change from green, orange to pink purple, indicating that DCFP@CTAB has excellent colorimetric visualization. Figure 6

[0059] The RGB of each color was extracted for quantitative analysis. Within the range of 0.1-30 μM of phoxim, the red channel and green channel ratio (R / G) in the color parameter showed a good linear relationship with the concentration of phoxim, and the linear equation was R / G = 0.0475C + 1.1193 (R2= 0.9984). The LOD was calculated to be 1.7 x 10-8M. 2 -7 M, as shown in Fig. 1C. Figure 7

[0060] (4) Detection of phoxim in real samples by DCFP@CTAB probe

[0061] Eight real samples were collected: river water, tap water, soil, baby bok choy, corn, cucumber, rice and green tea. The recovery rate of phoxim was determined by the standard addition recovery experiment. River water and tap water were directly used as the sample to be tested. 0.1 g of green tea leaves, 1.0 g of soil, 1.0 g of baby bok choy, 1.0 g of corn, 1.0 g of cucumber, and 1.0 g of rice were taken, respectively, and crushed or ground, and then added to 10 mL of ethanol as the extraction solvent. After 10 min of ultrasonic treatment at 250 W, the insoluble impurities were removed by centrifugation to obtain the extraction solution. The extraction solution was diluted 10 times with pure water and used as the sample to be tested.

[0062] ​​​The phoxim was directly added into each of the 100 μL of the sample to be tested, and the final concentration of the phoxim was 0.1, 0.5 and 1.0 μM respectively, and then 100 μL of the 80 μM DCFP@CTAB solution prepared in Example 1 was added, and the fluorescence spectrum of 510-650 nm was measured respectively, and the fluorescence intensity value at 538 nm was obtained. According to the linear standard curve obtained in Example 2, the recovery rate was calculated, and the results are shown in Table 1, the recovery rate is between 97.5-103.2%, and the relative standard deviation (RSD) is less than 3.6%. The verification by high performance liquid chromatography shows that there is no significant difference (P>0.05) between the results of the two methods.

[0063] The high performance liquid chromatography analysis conditions are referred to GB 9556-2008, the instrument model of the experiment is ChromaiLeaps, a C18 chromatographic column is used, and the specific operation conditions are as follows: mobile phase, methanol: water = 75:25, flow rate 1.0 mL / min, column temperature room temperature, detection wavelength 254 nm, and injection volume 10 μL.

[0064] Table 1. The standard addition recovery results of the fluorescence method and the HPLC method

[0065]

[0066] ND a :NotDetected.

[0067] (5) Preparation of the DCFP@CTAB test strip

[0068] 1. Preparation of the test strip

[0069] The circular filter paper with a diameter of 9 cm was cut into a test strip with a length of 4.2 cm and a width of 1.5 cm (it can also be processed into other shapes), and was respectively immersed in 2 mL of the 80 μM DCFP@CTAB solution prepared in Example 1, and after natural air drying, the DCFP@CTAB test strip was obtained.

[0070] 2. Fluorescence quenching standard card of the test strip

[0071] 30 μL of the ethanol solution of phoxim with different concentrations (0, 0.1, 1, 5, 7, 10, 30, 50, 70, 100, 300, 500, 700, 1000 μM) was added dropwise to the surface of the test strip, and the response was placed at room temperature for 5 min, and after natural drying, the change of the fluorescence of the test strip was recorded under the 365 nm ultraviolet lamp, and the fluorescence quenching standard card was prepared, and the color of the fluorescence test paper gradually changed from bright yellow-green fluorescence to dark fluorescence, as shown in Figure 8 .

[0072] 3. Quantitative analysis of the test strip

[0073] To determine the concentration of the sample more accurately, the quantitative analysis of the test strips was achieved by extracting the gray value (G) of each strip image. In the range of 0.1-500 μM of phoxim, the gray value change (ΔGray = G-G0) with the concentration of phoxim was plotted as Figure 9 Fig. 1a, in which the gray value change was well linear with the logarithm of the concentration of phoxim (lgC), and the linear equation was ΔGray = 23.7lgC + 15.5 (R 2 = 0.9968). The LOD was calculated to be 0.3 μM, as Figure 9 Fig. 1b.

Claims

1. A fluorescent colorimetric ionic liquid with the chemical formula [DCF][P] 66614 2. The structural formula is shown in formula (I):

2. A method for synthesizing the fluorescent colorimetric ionic liquid according to claim 1, characterized in that, The method is as follows: [P] 66614 [OH] and 2',7'-dichlorofluorescein were dissolved in anhydrous ethanol and reacted with stirring at 30–80 °C for 4–16 h. After the reaction was completed, the solvent was removed by vacuum evaporation, and the product was further dried under a nitrogen atmosphere at 60–100 °C to remove trace amounts of ethanol and water, yielding the fluorescent colorimetric ionic liquid; the [P] 66614 The molar ratio of [OH] to 2',7'-dichlorofluorescein is 1 to 3:

1.

3. A composite ion probe prepared from the fluorescent colorimetric ion liquid of claim 1, characterized in that, The composite ion probe is prepared as follows: the fluorescent colorimetric ion liquid ethanol solution of formula (I) is slowly added dropwise to the aqueous solution of hexadecyltrimethylammonium bromide, and after thorough stirring at room temperature, an electrostatically self-organized composite ion probe solution is obtained, denoted as DCFP@CTAB solution.

4. The composite ion probe as described in claim 3, characterized in that, The concentration of the ionic liquid ethanol solution is 0.1-1 mM, the concentration of the hexadecyltrimethylammonium bromide aqueous solution is 1-5 mM, and the volume ratio of the ionic liquid ethanol solution to the hexadecyltrimethylammonium bromide aqueous solution is 1:10-20.

5. The application of the composite ion probe of claim 3 in the detection of phoxim in actual samples.

6. The application as described in claim 5, characterized in that, The method of application is as follows: after grinding and pulverizing the solid actual sample to be tested, ethanol is used as the extraction solvent, and ultrasonic extraction is performed at 100-300W for 5-20 minutes. After centrifugation, the supernatant is collected. The composite ion probe is added to the supernatant or liquid actual sample to be tested, and the fluorescence spectrum at 510-650 nm is detected. The phoxim content in the actual sample to be tested is obtained according to the standard curve between the fluorescence intensity quenching value at 538 nm and the phoxim concentration.

7. The application as described in claim 6, characterized in that, The volumetric amount of ethanol used is 5–20 mL / g based on the actual mass of the solid sample to be tested; the concentration of the composite ion probe added to the supernatant or liquid sample to be tested is 1–80 μM.

8. The application as described in claim 6, characterized in that, The solid samples to be tested include tea leaves, soil, bok choy, corn, cucumber, or rice; the liquid samples to be tested include river water and tap water.

9. A rapid visual detection strip for phoxim prepared from the composite ion probe of claim 5.

10. The test strip as described in claim 9, characterized in that, The test strip is prepared by the following steps: the filter paper strip is moistened in the composite ion probe ethanol solution and then naturally air-dried. The application method of the test strip is as follows: add the test solution to the test strip, let it stand at room temperature for 5 minutes to respond, and after drying, record the fluorescence color of the test strip under a 365nm ultraviolet lamp; using the test strip fluorescence quenching standard card as a reference, preliminarily determine the content of phoxim in the test sample, extract the gray value of the test strip, and further determine the content of phoxim in the test sample based on the standard curve plotted according to the gray value change and the logarithm of phoxim concentration; the test strip fluorescence quenching standard card is made by adding phoxim ethanol solution to the test strip, letting it stand at room temperature for 5 minutes to respond, drying, and then recording the fluorescence color of the test strip under a 365nm ultraviolet lamp.

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