Fluorescent colorimetric ionic liquid, composite ion probe and application in phoxim detection

Abstract

The invention discloses a fluorescent colorimetric ionic liquid, a composite ionic probe and an application of the fluorescent colorimetric ionic liquid and the composite ionic probe in phoxim detection. According to the invention, the fluorescent colorimetric ionic liquid and a surfactant are subjected to electrostatic self-assembly to successfully synthesize the functionalized composite ionic probe; the sensitivity and selectivity of the compound ion probe for detecting phoxim are effectively improved, the detection limit is reduced, and the detection limit of phoxim fluorescence method detection can reach 3.0 * 10 <-8 > M and is lower than the minimum maximum allowable concentration specified by the national standard. The compound ion probe disclosed by the invention can be used for visually and conveniently detecting phoxim.

Description

(I) Technical field

[0001] The invention relates to a fluorescent colorimetric ionic liquid, a composite ion probe and applications in phoxim detection. (II) Background technology

[0002] Phoxim, an organophosphorus insecticide, is commonly used for antiparasitic and pest control of 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 and can cause severe clinical symptoms such as vomiting, coma, and even death. In order to ensure food safety, my country has adopted very strict legal regulations to control its residues. The National Food Safety Standard (GB 2763-2021) stipulates that 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 methods for detecting pesticide residues mainly include enzyme inhibition reaction detection, immune reaction detection, chromatography-mass spectrometry, biosensors, chemical optical detection, etc. The most commonly used method is still chromatography-mass spectrometry 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 organics are common optical probe materials. Due to the influence of various environmental factors, such as solvent, pH and concentration, the photophysical signal transduction of functionalized fluorophores is limited, which reduces their sensitivity; in addition, most of them have poor solubility in water. This requires a smart sensing method with amplified fluorescence response to analytes in aqueous solution. Micellar-based probes are considered to be promising candidates for chemical sensors, and surfactants are one of the effective methods to improve the solubility of organic matter in water. Ionic liquids (ILs) are functional materials composed only of anions and cations. Their high tunability enables the introduction of fluorescent organics as signal modules; in addition, their ionic properties promote the electrostatic self-assembly process to form ionic complexes with ionic surfactants such as cetyltrimethylammonium bromide (CTAB). CTAB can provide a positively charged surface environment and a hydrophobic internal micro-heterogeneous environment, so that probes that are difficult to dissolve in water can also have good solubility and high fluorescence emission intensity in water. Therefore, based on the electrostatic assembly technology, it is possible to develop a composite ion probe formed by self-assembly of surfactants and ionic liquids, and use the probe for the sensitive detection of phoxim. (III) Summary of the invention

[0004] The purpose of the present invention is to provide a fluorescent colorimetric ionic liquid, a composite ion probe and its application in the detection of phoxim. A new composite ion probe (DCFP@CTAB) formed by electrostatic self-assembly of ionic liquid and surfactant is constructed by adopting the "electrostatic and hydrophobic" dual-path strategy between the probe and phoxim. The ionic liquid is encapsulated in the hydrophobic core of CTAB, and the surfactant is used to improve the poor solubility of the hydrophobic ionic liquid in water and the fluorescence quenching problem; the probe has the advantages of high sensitivity, good specificity and visualized signal. The paper base developed at the same time can meet the needs of portable devices and can be applied to the detection of phoxim in a variety of real samples, providing a new idea for the convenient detection of phoxim in complex matrices.

[0005] The technical solution adopted by the present invention is:

[0006] The present invention provides a fluorescent colorimetric ionic liquid, the chemical formula of which is [DCF][P 66614 ] 2 , the structural formula is shown in formula (I):

[0007]

[0008] The present invention also provides a method for synthesizing the fluorescent colorimetric ionic liquid, which comprises:

[0009] [P 66614 ][OH] and 2',7'-dichlorofluorescein are dissolved in anhydrous ethanol, stirred and reacted at 30-80°C for 4-16h (preferably 60°C for 12h), and after the reaction, the solvent is evaporated under reduced pressure to remove the solvent, and further dried in a nitrogen atmosphere at 60-100°C to further remove trace ethanol and water in the product to obtain the fluorescent colorimetric ionic liquid; the [P 66614 The molar ratio of ][OH] to 2',7'-dichlorofluorescein is 1 to 3:1 (preferably 2:1).

[0010] Said [P 66614 ][OH] is made from trihexyl(tetradecyl)phosphine chloride ([P 66614 [Cl]) is obtained by dechlorination treatment with a strong alkaline anion exchange resin, wherein the specific dechlorination method is: 66614 The ethanol solution of [Cl] is added to a chromatography column filled with a strong basic anion exchange resin (preferably 717 strong basic anion exchange resin), slowly rinsed with anhydrous ethanol, and the effluent is collected to obtain [P 66614 ][OH].

[0011] The present invention also provides a composite ion probe, which is prepared by the following method: slowly adding a fluorescent colorimetric ionic liquid ethanol solution represented by formula (I) dropwise into a CTAB aqueous solution, and after sufficient stirring at room temperature, an electrostatically self-organized composite ion probe solution is obtained, which is recorded as a DCFP@CTAB solution;

[0012] The CTAB chemical formula is C 19 H 42 BrN, the structural formula is shown in formula (II):

[0013]

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

[0015] The present invention also provides an application of the composite ion probe in the detection of phoxim in actual samples.

[0016] Furthermore, the application method is as follows: after grinding and crushing the solid actual sample to be tested, using ethanol as an extractant, ultrasonically extracting for 5 to 20 minutes (preferably 15 minutes) at 100 to 300W (preferably 250W), centrifuging, and collecting the supernatant; adding the composite ion probe to the supernatant or liquid actual sample to be tested, detecting the fluorescence spectrum at 510 to 650nm, and obtaining the phoxim content in the actual sample to be tested based on a standard curve between the fluorescence intensity quenching value (ΔF) at 538nm and the phoxim concentration.

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

[0018] Further, the steps for drawing a standard curve between the fluorescence intensity quenching value (ΔF) at 538 nm and the concentration of phoxim are as follows: 100 μL of 80 μM composite ion probe solution and different volumes of phoxim aqueous solution are added to a centrifuge tube, and then the volume is made up to 1.0 mL with pure water so that the probe concentration is 8 μM and the final concentrations of phoxim are 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, and 10.0 μM, respectively. After mixing evenly, the mixture is poured into a quartz cuvette, and the fluorescence spectrum at 510 to 650 nm is measured. The fluorescence intensity quenching value (ΔF=F 0-F) as the ordinate and the standard curve was drawn with the concentration of phoxim as the abscissa.

[0019] Furthermore, the solid actual samples to be tested include tea leaves, soil, baby cabbage, corn, cucumber or rice; the liquid actual samples to be tested include river water and tap water.

[0020] The present invention also provides a test strip for rapid visual detection of phoxim prepared by the composite ion probe, wherein the test strip is prepared according to the following steps: soaking a filter paper strip in a composite ion probe ethanol solution (preferably 80 μM) and then naturally drying it;

[0021] The application method of the test strip is as follows: dripping the solution to be tested into the test strip, standing at room temperature for 5 minutes to respond, and after drying, recording the fluorescence color of the test strip under a 365nm ultraviolet lamp; using the test strip fluorescence quenching standard card as a reference, preliminarily judging the content of phoxim in the sample to be tested, extracting the gray value of the test strip, and further determining the content of phoxim in the sample to be tested according to the standard curve drawn by the gray value change value and the logarithmic value of the phoxim concentration; the test strip fluorescence quenching standard card is made by dripping the phoxim ethanol solution into the test strip, standing at room temperature for 5 minutes to respond, and after drying, 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, 1000 μM. The fluorescence color of the test paper gradually changes from bright yellow-green fluorescence to no fluorescence.

[0022] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

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

[0024] (2) The present invention successfully synthesized a functional composite ion probe DCFP@CTAB by electrostatic self-assembly of fluorescent colorimetric ionic liquid and surfactant. The hydrophobic ionic liquid was encapsulated into the hydrophobic core of CTAB. The positive corona and hydrophobic inner cavity around CTAB were used as adsorption units for phoxim. The positively charged hydrophilic corona attracted phoxim to approach preferentially through electrostatic attraction. The phoxim enriched in the corona could further diffuse into the fluorescent core. The "electrostatic and hydrophobic" dual-path strategy between the probe and phoxim not only improved the poor solubility of ionic liquid in water and fluorescence quenching, but also effectively improved the sensitivity and selectivity of the composite ion probe for detecting phoxim, and reduced the detection limit. The detection limit of DCFP@CTAB for phoxim fluorescence detection can reach 3.0×10 -8 M, which is lower than the minimum maximum allowable concentration specified in the national standard.

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

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

[0027] (5) The composite ion probe of the present invention exhibits high sensitivity and specificity to phoxim, realizes fluorescence and colorimetric quantitative detection of phoxim within a wide linear range, and exhibits multicolor changes visible to the naked eye; the composite ion probe of the present invention can be assembled into a portable paper substrate to realize rapid, on-site semi-quantitative detection of phoxim; the present invention can perform qualitative analysis and quantitative detection of phoxim residues in real samples, and provides a sensitive and visual detection method for the detection of organophosphorus pesticide residues. (IV) Description of the drawings

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

[0029] Figure 2 The fluorescence emission spectra 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 and the concentration of phoxim at different concentrations (a) and the linear calibration curve of the fluorescence quenching intensity and the concentration of phoxim (b).

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

[0032] Figure 5Fluorescence spectra and fluorescence quenching intensities of different pesticides detected by DCFP@CTAB: a represents the fluorescence spectra of different pesticides detected by DCFP@CTAB; b represents the fluorescence spectra of the coexistence of phoxim and interfering pesticides detected by DCFP@CTAB; c represents the fluorescence quenching intensity bar graph of different pesticides detected by DCFP@CTAB; d represents the fluorescence quenching intensity bar graph of the coexistence of phoxim and interfering pesticides detected by DCFP@CTAB.

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

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

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

[0036] Fig. 9 The graph of the grayscale change value (ΔGray) and the phoxim concentration of the DCFP@CTAB-based test strip image after adding different concentrations of phoxim (a) and the linear calibration curve of the grayscale change value and the logarithm of the phoxim concentration (b). (V) Specific implementation methods

[0037] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0038] The chemical reagents and solvents used in the examples were all commercially available analytical grade.

[0039] The fluorescence spectrum measurement conditions were set as an excitation wavelength of 508 nm, an emission wavelength of 510-650 nm, and excitation and emission slit widths of 2.5 nm and 5 nm, respectively.

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

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

[0042] 40g of [P 66614 The [Cl] liquid was added to a chromatography column containing 717 strongly basic anion exchange resin ([P66614 The mass ratio of [Cl] to strong basic anion exchange resin was 1:6), and it was slowly rinsed with anhydrous ethanol until the effluent was neutral. The alkaline effluent was collected to obtain 20.60 g of [P 66614 ][OH] ethanol solution 120mL, its concentration was determined to be 0.3430M by titration.

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

[0044] 5.83 mL of [P 66614 ][OH] ethanol solution (containing [P 66614 ][OH]1.0010g) and 0.4012g of 2',7'-dichlorofluorescein were added to a round-bottom flask at a molar ratio of 2:1, and an appropriate amount of anhydrous ethanol was added to dissolve, and the reaction was stirred in an oil bath at 60°C for 12 hours. The product after the reaction was used to remove the solvent ethanol using a rotary evaporator, and then heated at 80°C in a nitrogen atmosphere to further remove trace ethanol and water in the product, to obtain 1.1668g of a brown-red viscous liquid, which is the fluorescent colorimetric ionic liquid [DCF][P 66614 ] 2 . Just seal and store at room temperature. Ionic liquid [DCF][P 66614 ] 2 Zeta potential was measured after preparing 80 μM solution with water. The results are shown in Figure 1 Middle a.

[0045] (3) the ionic liquid [DCF][P prepared in step (2) 66614 ] 2 The ionic liquid mother solution (0.1 mM) was prepared with ethanol, and 320 μL of the mother solution was slowly added dropwise to 40 mL of CTAB aqueous solution (3.0 mM). After sufficient stirring at room temperature, a composite ion probe solution with a concentration of 80 μM 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 As shown in a, the electron transmission electron microscopy image is shown in Figure 1 As shown in b.

[0046] like Figure 1 As shown, the change in Zeta potential indicates that self-assembly occurs between the ionic liquid and CTAB; the transmission electron microscopy image shows that the formed probe presents a uniform spherical shape.

[0047] Example 2: Composite ion probe for sensitive and visual detection of phoxim in real samples

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

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

[0050] Phoxim was accurately weighed and dissolved in ethanol to prepare a 0.1 mM stock solution. During the fluorescence detection process, 100 μL of DCFP@CTAB solution (80 μM) and different volumes of phoxim stock solution were added to a centrifuge tube, and then diluted to 1.0 mL with pure water, so that the final concentrations of phoxim were 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 evenly, the mixture was poured into a quartz cuvette and the fluorescence spectrum at 510-650 nm was measured, as shown in FIG. 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 ordinate and the concentration of phoxim (0-10 μM) as the abscissa is as follows: Figure 3 As shown in a, the linear calibration curve of fluorescence quenching intensity and phoxim concentration (0-1.0 μM) is shown in Figure 3 As shown in b, the linear correlation equation is fitted as ΔF = 1335.7C + 47.1 (R 2 =0.9920), and the detection limit LOD was calculated to be 3.0×10 -8 M. Fluorescence quenching intensity of the emission peak at 538 nm (ΔF = F 0 -F) showed a good linear relationship with the concentration of phoxim in the range of 0.05 to 1 μM.

[0052] (2) 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 as follows: Figure 4 shown.

[0054] In 100 μL, 80 μM DCFP@CTAB solution, add Figure 4 The various pesticides shown were diluted to 1.0 mL with pure water, and the final concentration of each pesticide was 5.0 μM. No pesticide was added as a control ( Figure 5 The curve 0 in a). Detect the fluorescence spectrum at 510-650nm ( Figure 5 In a), a bar graph is drawn with the fluorescence quenching intensity (ΔF) at 538 nm as the ordinate and the type of pesticide as the abscissa ( Figure 5 c), demonstrating that the probe has excellent selectivity.

[0055] In addition, 5.0 μM phoxim and equivalent amounts of other interfering pesticides ( Figure 4 Pesticides 2-20), dilute to 1.0 mL with pure water, add interfering pesticides to a final concentration of 5.0 μM; and use no pesticide added as a control ( Figure 5 The fluorescence spectrum was recorded and histogram was drawn in the same way as in curve 0 in b. Figure 5 As shown in Figure 5b and Figure 5d, it is proved that the probe also has good anti-interference performance.

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

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

[0058] like Figure 6 As shown in Figure 1, under 365 nm UV light, 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 Figure 2B, under sunlight, the solution showed a wide range of color changes from green, orange to pink-purple, indicating that DCFP@CTAB also has excellent colorimetric visualization.

[0059] The RGB of each color was extracted for quantitative analysis. In the range of 0.1 to 30 μM of phoxim, the ratio of the red channel to the green channel (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 (R 2 =0.9984), the calculated LOD is 1.7×10 -7 M, such as 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 cabbage, corn, cucumber, rice and green tea, and the recovery rate of phoxim was determined by a spike recovery experiment. River water and tap water were used directly as test samples. 0.1g of green tea leaves, 1.0g of soil, 1.0g of baby cabbage, 1.0g of corn, 1.0g of cucumber, and 1.0g of rice were taken respectively, crushed or ground, and 10mL of ethanol was added as the extraction solvent. After 250W ultrasound for 10min, insoluble impurities were removed by centrifugation to obtain each extract. The extract was diluted 10 times with pure water and used as the test sample for standby use.

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

[0063] The HPLC analysis conditions were based on GB 9556-2008. The instrument model of this experiment was ChromaiLeaps, using a C18 chromatographic column. The specific operating conditions were: mobile phase, methanol: water = 75:25, flow rate 1.0 mL / min, column chamber temperature, detection wavelength 254 nm, injection volume 10 μL.

[0064] Table 1. Fluorescence and HPLC spike recovery results

[0065]

[0066] ND a :NotDetected.

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

[0068] 1. Preparation of test strips

[0069] A circular filter paper with a diameter of 9 cm was cut into test strips with a length of 4.2 cm and a width of 1.5 cm (it can also be processed into various other shapes), and immersed in 2 mL of the 80 μM DCFP@CTAB solution prepared in Example 1, and naturally air-dried to obtain DCFP@CTAB test strips.

[0070] 2. Fluorescence quenching standard card for test strips

[0071] 30 μL of ethanol solution of phoxim of different concentrations (0, 0.1, 1, 5, 7, 10, 30, 50, 70, 100, 300, 500, 700, 1000 μM) was added to the surface of the test strip, and the test strip was allowed to stand for 5 min at room temperature for response. After natural drying, the changes in the fluorescence of the test strip were recorded under a 365 nm ultraviolet lamp to make a fluorescence quenching standard card. The color of the fluorescent test strip gradually changed from bright yellow-green fluorescence to no fluorescence, such as Figure 8 shown.

[0072] 3. Quantitative analysis of test strips

[0073] In order to more accurately determine the concentration of the sample to be tested, the quantitative analysis of the test strips is achieved by extracting the gray value (G) of each strip image. In the range of phoxim 0.1 to 500 μM, the gray value change (ΔGray = GG 0 ) changes with the concentration of phoxim as shown in Fig. 9 In a, the grayscale change value has a good linear relationship with the logarithm of the concentration of phoxim (lgC), and the linear equation is ΔGray=23.7lgC+15.5(R 2 =0.9968), the LOD was calculated to be 0.3 μM. Fig. 9 Middle b.

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: [P 66614 ][OH] and 2',7'-dichlorofluorescein are dissolved in anhydrous ethanol, stirred and reacted at 30-80°C for 4-16h, and after the reaction, the solvent is evaporated under reduced pressure to remove the solvent, and further dried in a nitrogen atmosphere at 60-100°C to further remove trace ethanol and water in the product to obtain 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 ionic liquid according to claim 1, characterized in that: The composite ion probe is prepared as follows: the fluorescent colorimetric ionic liquid ethanol solution represented by formula (I) is slowly added dropwise to the hexadecyltrimethylammonium bromide aqueous solution, and after sufficient stirring at room temperature, an electrostatically self-organized composite ion probe solution is obtained, which is recorded as DCFP@CTAB solution.

4. The composite ion probe according to 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. Use of the composite ion probe according to claim 3 in the detection of phoxim in actual samples.

6. The use according to claim 5, characterized in that The application method is as follows: after grinding and crushing the solid actual sample to be tested, using ethanol as an extractant, ultrasonically extracting for 5 to 20 minutes under 100 to 300W conditions, centrifuging, and collecting the supernatant; adding the composite ion probe to the supernatant or liquid actual sample to be tested, detecting the fluorescence spectrum at 510 to 650nm, and obtaining the phoxim content in the actual sample to be tested based on a standard curve between the fluorescence intensity quenching value at 538nm and the phoxim concentration.

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

8. The use according to claim 6, characterized in that The solid actual samples to be tested include tea leaves, soil, baby cabbage, corn, cucumber or rice; the liquid actual samples to be tested include river water and tap water.

9. A test strip for rapid visual detection of phoxim prepared by the composite ion probe according to claim 5.

10. The test strip according to claim 9, characterized in that: The test strip is prepared according to the following steps: soaking the filter paper strip in a composite ion probe ethanol solution and then naturally drying it; The application method of the test strip is as follows: dripping a solution to be tested into the test strip, standing at room temperature for 5 minutes to respond, and after drying, recording the fluorescence color of the test strip under a 365nm ultraviolet lamp; using a fluorescence quenching standard card of the test strip as a reference, preliminarily judging the content of phoxim in the sample to be tested, extracting the gray value of the test strip, and further determining the content of phoxim in the sample to be tested according to a standard curve drawn between the gray value change value and the logarithmic value of the phoxim concentration; the fluorescence quenching standard card of the test strip is prepared by dripping a phoxim ethanol solution into the test strip, standing at room temperature for 5 minutes to respond, and after drying, recording the fluorescence color of the test strip under a 365nm ultraviolet lamp.

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