A manganese ion-doped perovskite nanocrystal composite and a method for rapid detection of 3-chloropropanol in edible oil

Abstract

The present invention discloses a perovskite nanocrystal composite doped with manganese ions and a method for rapid detection of 3-chloropropanol in edible oil. The perovskite nanocrystal doped with manganese ions has a molecular formula of CsPb (1‑x) Mn x Br3, and the composite is prepared by crystallizing and growing a perovskite solution in COFs material. The perovskite nanocrystal composite doped with manganese ions provided by the present invention improves the fluorescence intensity of the perovskite nanocrystal by doping with manganese ions, and increases the detection sensitivity to 3-chloropropanol; after being compounded with COFs, the fluorescence stability of the perovskite nanocrystal is improved, and the affinity with 3-chloropropanol is increased; the palladium-carbon activation technology of the present invention increases the reaction activity of 3-chloropropanol with the perovskite nanocrystal and the composite, improves the detection sensitivity and accuracy, significantly shortens the reaction time, and the method is simple, especially suitable for on-site rapid detection.

Description

Technical Field

[0001] The invention relates to a manganese ion-doped perovskite nanocrystal composite and a method for quickly detecting 3-chloropropanol in edible oil. Background Art

[0002] Edible oil and oil-containing foods (refined vegetable oil, fat, soy sauce and even infant formula) often produce chloropropanol compounds represented by 3-MCPD during processing, which seriously endangers food safety and human health. Generally, 3-MCPD is the esterification product of 3-MCPD (3-MCPD) and fatty acids. In recent years, 3-MCPD has been listed as a Class 2B carcinogen; and many studies have shown that 3-MCPD can harm the immune, nervous, reproductive and other systems and has strong toxicity (FoodChemistry, 2023, 403: 134332). Therefore, 3-MCPD has become one of the safety hazard factors and main monitoring indicators of edible oil; rapid and sensitive detection of 3-MCPD in edible oil has important economic and social value for ensuring its quality and safety.

[0003] At present, the detection of 3-MCPD is mainly based on gas phase-mass spectrometry. Although this method has high sensitivity and good repeatability, the complex pre-treatment is time-consuming and cumbersome, and requires large and expensive equipment, which is difficult to meet the needs of on-site monitoring and detection. Therefore, it is very necessary to develop a fast and sensitive detection method for 3-MCPD. Summary of the invention

[0004] The present invention aims to provide a manganese ion-doped perovskite nanocrystal complex and a method for rapidly detecting 3-chloropropanol in edible oil. The manganese ion-doped perovskite nanocrystal effectively improves the fluorescence signal, and the perovskite nanocrystal and COFs complex have significantly improved stability, enhanced lipophilicity, and higher reaction efficiency. In addition, the present invention uses noble metal activation to catalyze the rapid reaction of 3-chloropropanol ester with the perovskite nanocrystal and COFs complex, and the detection method has higher selectivity, sensitivity, accuracy, and better stability.

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

[0006] The present invention provides a method for preparing a manganese ion-doped perovskite nanocrystal composite, wherein the method comprises crystallizing and growing a Pb-Cs stock solution and a Mn-Cs stock solution for preparing manganese ion-doped perovskite nanocrystals in a COFs material to prepare the composite;

[0007] Pb-Cs stock solution: PbBr2 and CsBr were weighed, mixed and dispersed in N,N-dimethylformamide, and stirred until the solid was completely dissolved to prepare a Pb-Cs stock solution;

[0008] Mn-Cs stock solution: Weigh MnBr2 and CsBr, mix and disperse in N,N-dimethylformamide, stir until the solid is completely dissolved, and prepare Mn-Cs stock solution; the molecular formula of the manganese ion-doped perovskite nanocrystal is CsPb (1-x) Mn x Br3, x is 0.1, 0.2, 0.3, 0.4 or 0.5.

[0009] Furthermore, it is preferred that x is 0.3.

[0010] Furthermore, the COFs material includes 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 1,3,5-tris(4-formylphenyl), 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, or 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinylterephthalaldehyde covalently connected.

[0011] Furthermore, the concentrations of PbBr2 and CsBr in the Pb-Cs stock solution were both 0.04 mol / L.

[0012] Furthermore, the concentrations of MnBr2 and CsBr in the Mn-Cs stock solution were both 0.04 mol / L.

[0013] Further, the composite is prepared as follows:

[0014] The Pb-Cs stock solution, the Mn-Cs stock solution and the COFs material are ultrasonically mixed for 1-3 minutes (preferably 1 minute), stirred for 1-3 hours (preferably 1 hour), oleic acid and oleylamine are added, stirred for 5-15 minutes (preferably 10 minutes), toluene is added, stirred for 1-3 minutes (preferably 2 minutes), centrifuged (at 8000 rpm for 5 minutes), and the precipitate is dried (preferably evaporated and dried in a fume hood) to obtain the composite.

[0015] Further, the amount of the Pb-Cs stock solution is calculated based on the amount of Pb substance, the amount of the Mn-Cs stock solution is calculated based on the amount of Mn substance, and the molar ratio of Pb to Mn is 9:1-1:1, preferably 7:3. The volume ratio of oleic acid to oleylamine is 1:1, and the ratio of the total volume of oleic acid and oleylamine to the total volume of the Pb-Cs stock solution and the Mn-Cs stock solution is 0.1:1; the ratio of the volume of toluene to the total volume of the Pb-Cs stock solution and the Mn-Cs stock solution is 20:1.

[0016] Furthermore, the ratio of the mass of the COFs material to the total volume of the Pb-Cs stock solution and the Mn-Cs stock solution is 0.5 g:40-100 mL, preferably 0.5 g:40 mL.

[0017] Furthermore, the COFs material is prepared according to one of the following methods: (1) 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and 1,3,5-tris(4-formylphenyl)benzene (TFP) are added to a beaker, and then acetonitrile and acetic acid are added, shaken and evenly mixed, and ultrasonicated for 10 minutes until the monomers are completely dispersed; after standing at room temperature for 3 days, the precipitate is collected by centrifugation at 8000 rpm for 5 minutes, washed three times with DMF, washed once with tetrahydrofuran, washed twice with anhydrous ethanol, and dried at 75°C to obtain TTA-TFP; the mass ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to 1,3,5-tris(4-formylphenyl)benzene is 2.13:2.34; the volume of acetonitrile used is 500 mL / 2.13 based on the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine. g, the volume ratio of acetonitrile to acetic acid is 25:3; (2) 1,3,5-tris(4-aminophenyl)benzene (TPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMA) are added to a beaker, and then 1,4-dioxane, mesitylene and acetic acid are added. After stirring at room temperature for 72 hours, the precipitate is collected by centrifugation at 8000 rpm for 5 minutes, washed three times with methanol, and dried at 75 °C to obtain TPB-DMA; the mass ratio of 1,3,5-tris(4-aminophenyl)benzene to 2,5-dimethoxybenzene-1,4-dicarboxaldehyde is 11.2:9.6; the volume amount of 1,4-dioxane is 300 mL / 11.2 g. g, the volume ratio of 1,4-dioxane to mesitylene and acetic acid is 3:3:1; (3) 1,3,5-tris(4-aminophenyl)benzene (TPB) and 2,5-divinylterephthalaldehyde (DVA) are added to a beaker, and acetonitrile and acetic acid are added, stirred for 1 minute, ultrasonicated for 1 minute, and allowed to stand at room temperature for 3 days. The precipitate is collected by centrifugation at 8000 rpm for 5 minutes, washed once with tetrahydrofuran, washed three times with anhydrous ethanol, and dried at 75°C to obtain TPB-DVA; the mass ratio of 1,3,5-tris(4-aminophenyl)benzene to 2,5-divinylterephthalaldehyde is 0.5:4; the volume amount of acetonitrile is 6 L / g based on the mass of 1,3,5-tris(4-aminophenyl)benzene, and the volume ratio of acetonitrile to acetic acid is 6:1.

[0018] The invention also provides a manganese ion-doped perovskite nanocrystal composite prepared by the method.

[0019] The present invention also provides a method for rapidly detecting 3-chloropropanol in edible oil by using a manganese ion-doped perovskite nanocrystal complex. The method comprises: adding palladium carbon to the edible oil to be tested, vortexing for 5-15 s (preferably 10 s), centrifuging, taking the supernatant and adding it to a toluene dispersion of the manganese ion-doped perovskite nanocrystal complex, vortexing for 5-15 s (preferably 10 s), standing at room temperature for 10-30 min (15 min), and detecting a 400-700 nm fluorescence spectrum; and calculating the 3-chloropropanol content in the edible oil to be tested by using a standard curve of the fluorescence intensity of a characteristic peak and the concentration of 3-chloropropanol detected by replacing edible oil with 3-chloropropanol under the same conditions or a standard curve of the characteristic peak shift value and the concentration of 3-chloropropanol according to the characteristic peak fluorescence intensity or the characteristic peak shift value.

[0020] Furthermore, the amount of palladium carbon added is 5-15 mg / mL, preferably 10 mg / mL, based on the volume of the edible oil to be tested; the concentration of the toluene dispersion of the perovskite nanocrystal complex doped with manganese ions is 1-5 mg / mL (preferably 1 mg / mL), and the volume ratio of the added amount to the supernatant is 1-3:1 (preferably 1:1).

[0021] Furthermore, the mass content of palladium in the palladium carbon is 10%.

[0022] Further, the standard curve of the fluorescence intensity of the characteristic peak and the concentration of 3-chloropropanol or the standard curve of the characteristic peak offset value and the concentration of 3-chloropropanol is prepared as follows:

[0023] Soybean oil with different 3-MCPD contents was added with palladium carbon, vortexed for 10 seconds, and centrifuged; the supernatant was taken, and toluene dispersion of perovskite nanocrystal complex doped with manganese ions was added to each of them, vortexed for 10 seconds, and allowed to stand at room temperature for 15 minutes, and the fluorescence spectrum of 400-700nm was detected; the 3-MCPD contents were 1, 10, 100, 500, 1000, 2000, and 4000 µg / g, respectively; the 3-MCPD content of 0 was used as the control group;

[0024] The characteristic peak position of different 3-MCPD contents was recorded as λ, and the fluorescence intensity was recorded as I; the characteristic peak position of the control group was recorded as λ0, and the fluorescence intensity was recorded as I0; the Lg value of 3-MCPD content was used as the horizontal coordinate and (λ0-λ) as the vertical coordinate to fit and construct the offset quantitative standard curve;

[0025] The fluorescence intensity quantitative standard curve was constructed by fitting, with the Lg value of 3-MCPD content as the horizontal axis and (I0-I) / I0 as the vertical axis.

[0026] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0027] (1) The manganese ion-doped perovskite nanocrystals provided by the present invention improve the fluorescence intensity of the perovskite nanocrystals by doping with manganese ions, and increase the detection sensitivity of 3-MCPD; after being compounded with COFs, the fluorescence stability of the perovskite nanocrystals is improved, and the affinity with 3-MCPD is increased;

[0028] (2) The palladium-carbon activation technology of the present invention increases the reaction activity of 3-MCPD with perovskite nanocrystals and complexes, significantly improving the detection sensitivity (the detection limit of the wavelength shift method is 1 µg / g, and the detection limit of the fluorescence intensity reduction method is 0.274 µg / g) and accuracy (compared with the detection results of the spiked recovery samples, the average error of the wavelength shift method is 8.68%; the average error of the fluorescence intensity reduction method is 6.29%), and the reaction time is significantly shortened (from 6 hours to 15-20 minutes).

[0029] (3) The method of the present invention is simple to operate and has mild reaction conditions (can be carried out at room temperature), and is particularly suitable for on-site rapid detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 , CsPb doped with different types of ions 0.9 B 0.1 Fluorescence spectra of Br3 NCs (B=Mn, Sn, Co, Zn).

[0031] Figure 2 、CsPb doped with different contents of Mn ions (1-x) Mn x Fluorescence spectra of Br3 NCs (x=0-0.5).

[0032] Figure 3 , CsPb 0.7 Mn 0.3 Br3@COFs and CsPb 0.7 Mn 0.3 Relative fluorescence intensity curve of Br3 NCs after continuous UV light irradiation.

[0033] Figure 4 、Different COFs and CsPb 0.7 Mn 0.3 Fluorescence spectrum of Br3 NCs after composite.

[0034] Figure 5 Without pretreatment, CsPb 0.7 Mn 0.3 Fluorescence spectrum of Br3@TPB-DMA-COF to 3-MCPD in oils and fats.

[0035] Figure 6 Without pretreatment, CsPb 0.7Mn 0.3 Quantitative standard curve of Br3@TPB-DMA-COF for the change of 3-MCPD fluorescence intensity in oils and fats.

[0036] Figure 7 Without pretreatment, CsPb 0.7 Mn 0.3 Quantitative standard curve of wavelength shift of 3-MCPD in oils and fats by Br3@TPB-DMA-COF.

[0037] Figure 8 , Pd-Carbon pretreatment, CsPb 0.7 Mn 0.3 Fluorescence spectrum of Br3@COFs to 3-MCPD in oils and fats.

[0038] Fig. 9 , Pd-Carbon pretreatment, CsPb 0.7 Mn 0.3 Quantitative calibration curve of Br3@COFs on the change of 3-MCPD fluorescence intensity in oils and fats.

[0039] Fig.10 , Pd-Carbon pretreatment, CsPb 0.7 Mn 0.3 Quantitative standard curve of wavelength shift of 3-MCPD in oils and fats by Br3@COFs.

[0040] Fig.11 , Pd-Carbon pretreatment, CsPb 0.7 Mn 0.3 Fluorescence visualization of 3-MCPD in oils and fats by Br3@COFs. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0042] Preparation of reagents used in the embodiments of the present invention:

[0043] (1) Pb-Cs stock solution: Weigh 14.70 g PbBr2 and 8.50 g CsBr, mix and disperse in 1 L DMF (N,N-dimethylformamide), and stir until the solid is completely dissolved to prepare a Pb-Cs stock solution containing 0.04 mol / L PbBr2 and 0.04 mol / L CsBr.

[0044] (2) Mn-Cs stock solution: Weigh 8.50 g MnBr2 and 8.50 g CsBr, mix and disperse in 1 L DMF, and stir until the solid is completely dissolved to prepare a Mn-Cs stock solution containing 0.04 mol / L MnBr2 and 0.04 mol / L CsBr.

[0045] (3) Sn-Cs stock solution: Weigh 11.02 g MnBr2 and 8.50 g CsBr, mix and disperse in 1 L DMF, and stir until the solid is completely dissolved to prepare a Mn-Cs stock solution containing 0.04 mol / L MnBr2 and 0.04 mol / L CsBr.

[0046] (4) Co-Cs stock solution: Weigh 8.66 g MnBr2 and 8.50 g CsBr, mix and disperse in 1 L DMF, and stir until the solid is completely dissolved to prepare a Mn-Cs stock solution containing 0.04 mol / L MnBr2 and 0.04 mol / L CsBr.

[0047] (5) Zn-Cs stock solution: Weigh 8.91 g ZnBr2 and 8.50 g CsBr, mix and disperse in 1 L DMF, and stir until the solid is completely dissolved to prepare a Zn-Cs stock solution containing 0.04 mol / L ZnBr2 and 0.04 mol / L CsBr.

[0048] Preparation method of CsPbBr3 NCs: 60 mL of Pb-Cs stock solution was transferred, 3 mL of oleic acid and 3 mL of oleylamine were added, and 1.2 L of toluene was added after vigorous stirring for 5 min. The mixed solution was centrifuged at 8000 rpm for 5 min, and the precipitate was taken and evaporated and dried in a fume hood for later use. 1.3 g of CsPbBr3 nanocrystals were obtained, which were recorded as CsPbBr3 NCs (yield of about 93%), and the average particle size was about 8.8 nm. As a control group, toluene was used to prepare a dispersion of 0.5 mg / mL, and the fluorescence spectrum was tested using the method in Example 1. The results are shown in FIG. Figure 1 shown.

[0049] The room temperature in the embodiment of the present invention is 25-30°C.

[0050] Example 1-4: Effect of doping ion types on CsPb 0.9 B 0.1 Effect of Br3 NCs fluorescence intensity

[0051] Appropriate doping ions can not only reduce the proportion of Pb in CsPbBr3 NCs, but also optimize the fluorescence properties of CsPbBr3 NCs. To this end, four different doping ions were synthesized:

[0052] Example 1, CsPb 0.9 Mn 0.1 Synthesis and fluorescence intensity of Br3 NCs

[0053] Take 54 mL of Pb-Cs stock solution and 6 mL of Mn-Cs stock solution, add 3 mL of oleic acid and 3 mL of oleylamine, stir vigorously for 5 min, then add 1.2 L of toluene and stir for 5 min. Centrifuge the mixed solution at 8000 rpm for 5 min, take the precipitate, evaporate and dry in a fume hood for later use, and obtain CsPb 0.9 Mn 0.1 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0054] The prepared CsPb 0.9 Mn 0.1 Br3 NCs were dispersed in toluene to obtain a dispersion with a concentration of 0.5 mg / mL. Then, the fluorescence spectrum of 400-700 nm after 365 nm laser excitation was measured using a multifunctional microplate reader (Synergy H1, Bioteck, USA). The results are shown in Figure 1 shown.

[0055] Example 2, CsPb 0.9 Sn 0.1 Synthesis and fluorescence intensity of Br3 NCs

[0056] Take 54 mL of Pb-Cs stock solution and 6 mL of Sn-Cs stock solution, add 3 mL of oleic acid and 3 mL of oleylamine, stir vigorously for 5 min, then add 1.2 L of toluene and stir for 5 min. Centrifuge the mixed solution at 8000 rpm for 5 min, take the precipitate, evaporate and dry in a fume hood for later use, and obtain CsPb 0.9 Sn 0.1 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0057] The prepared CsPb 0.9 Sn 0.1 Br3 NCs were dispersed in toluene to obtain a dispersion with a concentration of 0.5 mg / mL. Then, the fluorescence spectrum of 400-700 nm after 365 nm laser excitation was measured using a multifunctional microplate reader (Synergy H1, Bioteck, USA). The results are shown in Figure 1 shown.

[0058] Example 3, CsPb 0.9 Co 0.1 Synthesis and fluorescence intensity of Br3 NCs

[0059] Take 54 mL of Pb-Cs stock solution and 6 mL of Co-Cs stock solution, add 3 mL of oleic acid and 3 mL of oleylamine, stir vigorously for 5 min, then add 1.2 L of toluene and stir for 5 min. Centrifuge the mixed solution at 8000 rpm for 5 min, take the precipitate, evaporate and dry in a fume hood for later use, and obtain CsPb 0.9 Co 0.1 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0060] The prepared CsPb 0.9 Co 0.1 Br3 NCs were dispersed in toluene to obtain a dispersion with a concentration of 0.5 mg / mL. Then, the fluorescence spectrum of 400-700 nm after 365 nm laser excitation was measured using a multifunctional microplate reader (Synergy H1, Bioteck, USA). The results are shown in Figure 1 shown.

[0061] Example 4, CsPb 0.9 Zn 0.1 Synthesis and fluorescence intensity of Br3 NCs

[0062] Take 54 mL of Pb-Cs stock solution and 6 mL of Zn-Cs stock solution, add 3 mL of oleic acid and 3 mL of oleylamine, stir vigorously for 5 min, then add 1.2 L of toluene and stir for 5 min. Centrifuge the mixed solution at 8000 rpm for 5 min, take the precipitate, evaporate and dry in a fume hood for later use, and obtain CsPb 0.9 Zn 0.1 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0063] The prepared CsPb 0.9 Zn 0.1 Br3 NCs were dispersed in toluene to obtain a dispersion with a concentration of 0.5 mg / mL. Then, the fluorescence spectrum of 400-700 nm after 365 nm laser excitation was measured using a multifunctional microplate reader (Synergy H1, Bioteck, USA). The results are shown in Figure 1 shown.

[0064] Figure 1 The results show that CsPb 0.9 B 0.1The fluorescence intensity of Br3 NCs is quite different. Compared with CsPbBr3 NCs (fluorescence peak position 512 nm, fluorescence intensity 32956 au), CsPb 0.9 Mn 0.1 The fluorescence peak position of Br3 NCs remained basically unchanged, but the fluorescence intensity was enhanced (35677 au); while CsPb 0.9 Co 0.1 The fluorescence intensity of Br3 NCs was greatly reduced (22931 au); for CsPb 0.9 Sn 0.1 Br3 NCs (33084 au) and CsPb 0.9 Zn 0.1 Br3 NCs (32622 au), the fluorescence intensity is basically unchanged. Therefore, Mn-doped CsPb 0.9 Mn 0.1 The following experiments were carried out on Br3 NCs.

[0065] Example 5-8 Effect of Mn ion doping amount on CsPb (1-x) Mn x Effect of Br3 NCs fluorescence intensity

[0066] The amount of ion doping will affect the CsPb (1-x) Mn x The crystal structure of Br3 NCs has a significant impact on their fluorescence intensity. To this end, four materials with different doping ratios were synthesized:

[0067] Example 5, CsPb 0.8 Mn 0.2 Synthesis and fluorescence intensity of Br3 NCs

[0068] Take 48 mL of Pb-Cs stock solution and 12 mL of Mn-Cs stock solution and add them to a 5 L beaker. Ultrasonic dispersion is performed for 1 minute. After stirring for 1 hour, 3 mL of oleic acid and 3 mL of oleylamine are added. After stirring for 10 minutes, 1.2 L of toluene is added and stirred for 2 minutes. Centrifuge at 8000 rpm for 5 minutes and evaporate and dry in a fume hood to obtain CsPb 0.8 Mn 0.2 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0069] CsPb 0.8 Mn 0.2 Br3 NCs were prepared into a dispersion with a concentration of 0.5 mg / mL in toluene, and the fluorescence intensity was measured using the method of Example 1. Figure 2 shown.

[0070] Example 6, CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3 NCs

[0071] Take 42 mL of Pb-Cs stock solution and 18 mL of Mn-Cs stock solution and add them to a 5 L beaker. Ultrasonic dispersion is performed for 1 minute. After stirring for 1 hour, 3 mL of oleic acid and 3 mL of oleylamine are added. After stirring for 10 minutes, 1.2 L of toluene is added and stirred for 2 minutes. Centrifuge at 8000 rpm for 5 minutes and evaporate and dry in a fume hood to obtain CsPb 0.7 Mn 0.3 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0072] CsPb 0.7 Mn 0.3 Br3 NCs were prepared into a dispersion with a concentration of 0.5 mg / mL using toluene, and the fluorescence intensity was measured using the method in Example 1. Figure 2 shown.

[0073] Example 7, CsPb 0.6 Mn 0.4 Synthesis and fluorescence intensity of Br3 NCs

[0074] Take 36 mL of Pb-Cs stock solution and 24 mL of Mn-Cs stock solution and add them to a 5 L beaker. Ultrasonic dispersion is performed for 1 minute. After stirring for 1 hour, 3 mL of oleic acid and 3 mL of oleylamine are added. After stirring for 10 minutes, 1.2 L of toluene is added and stirred for 2 minutes. Centrifuge at 8000 rpm for 5 minutes and evaporate and dry in a fume hood to obtain CsPb 0.6 Mn 0.4 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0075] CsPb 0.6 Mn 0.4 Br3 NCs were prepared into a dispersion with a concentration of 0.5 mg / mL using toluene, and the fluorescence intensity was measured using the method in Example 1. Figure 2 shown.

[0076] Example 8, CsPb 0.5 Mn 0.5 Synthesis and fluorescence intensity of Br3 NCs

[0077] Take 30 mL of Pb-Cs stock solution and 30 mL of Mn-Cs stock solution and add them to a 5 L beaker. Ultrasonic dispersion is performed for 1 minute. After stirring for 1 hour, 3 mL of oleic acid and 3 mL of oleylamine are added. After stirring for 10 minutes, 1.2 L of toluene is added and stirred for 2 minutes. Centrifuge at 8000 rpm for 5 minutes and evaporate and dry in a fume hood to obtain CsPb 0.5 Mn 0.5 Br3 NCs, 1.3 g, average particle size about 8.7 nm.

[0078] CsPb 0.5 Mn 0.5 Br3 NCs were prepared into a dispersion with a concentration of 0.5 mg / mL using toluene, and the fluorescence intensity was measured using the method in Example 1. Figure 2 shown.

[0079] Figure 2 The results show that manganese ion doping does not change the characteristic fluorescence wavelength (512 nm) of CsPbBr3 NCs, but significantly increases the fluorescence intensity of CsPbBr3 NCs, thereby improving the sensitivity and detection limit of the 3-MCPD method. S Pb (1-x) Mn x The excitation fluorescence wavelength of Br3 NCs increased from 32697 au to 35598-69433 au, especially when Mn ions were doped at 30%, the fluorescence of quantum dots was the strongest at 69433 au. However, when Mn ions were doped at 50%, the fluorescence of nanocrystals decreased.

[0080] Example 9-12 Effect of COFs Type on CsPb 0.7 Mn 0.3 Effect of Br3 NCs fluorescence intensity

[0081] Appropriate COFs should have a good pore size distribution to allow CsPb 0.7 Mn 0.3 Br3 NCs should grow and distribute well in them; they should also have good hydrophobicity to effectively promote the oil carrying 3-MCPD to enter the pores and contact and react with the nanocrystals. In addition, the fluorescence intensity of the nanocrystals grown in COFs should be high to ensure the monitoring sensitivity of 3-MCPD. Four different COFs were synthesized separately.

[0082] Example 9, CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3@TTA-TFP

[0083] 1. TTA-TFP

[0084] 2.13 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and 2.34 g of 1,3,5-tris(4-formylphenyl)benzene (TFP) were added to a 5 L beaker, and then 500 mL of acetonitrile and 60 mL of acetic acid (12 M) were added and shaken, and ultrasonicated for 10 minutes until the monomers were completely dispersed. After standing at room temperature for 3 days, the precipitate was collected by centrifugation at 8000 rpm for 5 minutes, washed three times with DMF, washed once with tetrahydrofuran, washed twice with anhydrous ethanol, and dried at 75 °C to obtain 4.25 g of TTA-TFP powder.

[0085] 2. CsPb 0.7 Mn 0.3 Preparation and fluorescence intensity of Br3@COFs

[0086] Take 42 mL of Pb-Cs stock solution, 18 mL of Mn-Cs stock solution and 0.5 g of TTA-TFP powder and add them to a 5 L beaker, ultrasonicate for 1 minute, stir for 1 hour, add 3 mL of oleic acid and 3 mL of oleylamine, stir for 10 minutes, add 1.2 L of toluene, stir for 2 minutes, centrifuge at 8000 rpm for 5 minutes, and evaporate and dry in a fume hood to obtain CsPb 0.7 Mn 0.3 Br3@COFs powder 1.60 g.

[0087] Cb 0.7 Mn 0.3 Br3@COFs was prepared into a dispersion with a concentration of 0.5 mg / mL using toluene, and its fluorescence intensity was measured using the method of Example 1. Figure 3 shown.

[0088] Example 10, CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3@TPB-DMA

[0089] 1. TPB-DMA

[0090] 11.2 g of 1,3,5-tris(4-aminophenyl)benzene (TPB) and 9.6 g of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMA) were added to a 5 L beaker, followed by 300 mL of 1,4-dioxane, 300 mL of mesitylene and 100 mL of acetic acid. After stirring at room temperature for 72 hours, the precipitate was collected by centrifugation at 8000 rpm for 5 minutes, washed three times with methanol, and dried at 75 °C to obtain 19.97 g of TPB-DMA powder.

[0091] 2. CsPb 0.7 Mn 0.3Br3@ TPB-DMA

[0092] The TTA-TFP powder in step 2 of Example 9 was replaced with the TPB-DMA powder prepared in step 1, and the other operations were the same to obtain 1.453 g of CsPb 0.7 Mn 0.3 Br3@TPB-DMA, and measured its fluorescence absorption. The results are as follows Figure 3 shown.

[0093] In addition, CsPb 0.7 Mn 0.3 Br3@TPB-DMA and CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3 NCs under continuous irradiation with 365 nm UV light is shown in Figure 2. Figure 4 As shown, the results show that CsPb 0.7 Mn 0.3 After long-term exposure to ultraviolet light, the fluorescence intensity of Br3 NCs decreases rapidly until it is annihilated; while CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3@TPB-DMA slowly decreased. 0.7 Mn 0.3 The fluorescence intensity of Br3@TPB-DMA is 96% of the original intensity, while CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3 NCs was only 39% of the original intensity; after 10 h of UV irradiation, the fluorescence intensity of CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3@TPB-DMA was 77% of the original intensity, while that of CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3 NCs is only 3.3% of the original intensity (basically annihilated). Therefore, the composite of TPB-DMA greatly improves the fluorescence intensity of CsPb 0.7 Mn 0.3 Fluorescence stability of Br3@TPB-DMA.

[0094] Example 11, CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3@TPB-DVA

[0095] 1. TPB-DVA

[0096] 0.5 g of 1,3,5-tris(4-aminophenyl)benzene (TPB) and 4 g of 2,5-divinylterephthalaldehyde (DVA) were added to a 5 L beaker, and then 3 L of acetonitrile and 500 mL of acetic acid were added, stirred for 1 minute, and ultrasonicated for 1 minute. After standing at room temperature for 3 days, the precipitate was collected by centrifugation at 8000 rpm for 5 minutes, washed once with tetrahydrofuran, washed three times with anhydrous ethanol, and dried at 75 °C to obtain 4.23 g of TPB-DVA powder.

[0097] 2. CsPb 0.7 Mn 0.3 Br3@ TPB-DVA

[0098] The TTA-TFP powder in step 2 of Example 9 was replaced with TPB-DVA prepared in step 1, and other operations were performed in the same manner to obtain 1.61 g of CsPb 0.7 Mn 0.3 Br3@TPB-DVA, and measured its fluorescence absorption. The results are as follows Figure 3 shown.

[0099] Example 12, CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3@PTP-PDA

[0100] 1.PTP-PDA

[0101] PTP: 180 g p-hydroxybenzaldehyde and 58.5 g NaOH were added to a mixed solution of 2.4 L acetone and 2.4 L water, which was recorded as solution A. Ice bath was set to 0 °C. 90 g cyanuric chloride was dissolved in 2.4 L acetone, which was recorded as solution B. Solution B was slowly dripped into solution A over a period of 1 h. After reacting at room temperature for 12 h, the mixture was filtered and the precipitate was washed with a large amount of pure water. The mixture was dried at 80 °C to obtain 162.8 g of TPT as a white solid product. Then, 4.4 g TPT, 1.63 g p-phenylenediamine, 75 mL n-butanol and 100 mL o-dichlorobenzene were added to a 500 mL beaker, stirred vigorously for 10 minutes, and ultrasonicated for 10 minutes to obtain a uniform solution. 25 mL n-butanol containing 400 mg phosphotungstic acid was added, and the mixture was reacted at room temperature for 2 hours. The mixture was centrifuged at 8000 rpm for 5 minutes, and the precipitated product was washed once with acetone and twice with tetrahydrofuran, and dried at 75 °C to obtain 5.79 g of PTP-PDA powder.

[0102] 2. CsPb 0.7 Mn 0.3 Br3@PTP-PDA

[0103] The TTA-TFP powder in step 2 of Example 9 was replaced with the PTP-PDA prepared in step 1, and the other operations were the same to obtain 1.54 g of CsPb 0.7 Mn 0.3 Br3@PTP-PDA, and measured its fluorescence absorption. The results are as follows Figure 3 shown.

[0104] Figure 3 The data show that different COFs and CsPb 0.7 Mn 0.3 The composite of Br3 NCs will not change the fluorescence emission peak position (about 514 nm), but will significantly affect its fluorescence intensity. 0.7 Mn 0.3 The composite of Br3 NCs has the highest fluorescence intensity, which is 58508 au; while the composite fluorescence intensity of PTP-PDA is the lowest, which is 7737 au, and a small fluorescence peak appears at 460 nm, indicating that CsPb 0.7 Mn 0.3 The growth effect of Br3 NCs on PTP-PDA was poor.

[0105] Example 13-15 TPB-DMA and CsPb 0.7 Mn 0.3 Effect of Br3 NCs ratio on fluorescence intensity

[0106] The appropriate material ratio should be able to provide both CsPb 0.7 Mn 0.3 The growth of Br3 NCs provides sufficient pore structure and can also ensure high fluorescence intensity. Four composite materials with different ratios were synthesized respectively. Here, the amount of TPB-DMA was fixed (0.5 g) and the amount of CsPb 0.7 Mn 0.3 Different ratios were achieved by adjusting the amount of the total stock solution of Br3 NCs (including the total volume of the Pb-Cs stock solution and the Mn-Cs stock solution, which were 40 mL, 60 mL, 80 mL, and 100 mL, respectively).

[0107] Example 13, 0.5 g TPB-DMA and CsPb 0.7 Mn 0.3 Synthesis of Br3 NCs (40 mL total stock solution) and their fluorescence intensity

[0108] 28 mL of Pb-Cs stock solution and 12 mL of Mn-Cs stock solution and 0.5 g of TPB-DMA prepared by the method of Example 10 were added to a 5 L beaker, ultrasonicated for 1 minute, stirred for 1 hour, and then 2 mL of oleic acid and 2 mL of oleylamine were added. After stirring for 10 minutes, 0.8 L of toluene was added and stirred for 2 minutes. The mixture was centrifuged at 8000 rpm for 5 minutes and evaporated and dried in a fume hood to obtain 1.227 g of CsPb 0.7 Mn 0.3 Br3@TPB-DMA.

[0109] Cb 0.7 Mn 0.3 Br3@TPB-DMA was prepared into a dispersion of 0.5 mg / mL using toluene, and its fluorescence intensity at 512 nm was measured using the method of Example 1, as shown in Table 1.

[0110] Example 14: 0.5 g TPB-DMA and CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3 NCs (80 mL total stock solution)

[0111] 56 mL of Pb-Cs stock solution and 24 mL of Mn-Cs stock solution and 0.5 g of TPB-DMA prepared by the method of Example 10 were added to a 5 L beaker, ultrasonicated for 1 minute, stirred for 1 hour, 4 mL of oleic acid and 4 mL of oleylamine were added, stirred for 10 min, 1.6 L of toluene was added, stirred for 2 min, centrifuged at 8000 rpm for 5 minutes, and the precipitation was evaporated and dried in a fume hood to obtain 1.998 g of CsPb 0.7 Mn 0.3 Br3@TPB-DMA.

[0112] Cb 0.7 Mn 0.3 Br3@TPB-DMA was prepared into a dispersion of 0.5 mg / mL using toluene, and its fluorescence intensity at 512 nm was measured using the method of Example 1, as shown in Table 1.

[0113] Example 15, 0.5 g TPB-DMA and CsPb 0.7 Mn 0.3 Synthesis and fluorescence intensity of Br3 NCs (100 mL total stock solution)

[0114] 70 mL of Pb-Cs stock solution, 30 mL of Mn-Cs stock solution and 0.5 g of COFs were added to a 5 L beaker, ultrasonicated for 1 minute, stirred for 1 hour, 5 mL of oleic acid and 5 mL of oleylamine were added, stirred for 10 min, 2 L of toluene was added, stirred for 2 min, centrifuged at 8000 rpm for 5 minutes, and evaporated and dried in a fume hood to obtain 2.358 g of CsPb 0.7 Mn 0.3 Br3@TPB-DMA.

[0115] Cb 0.7 Mn 0.3 Br3@TPB-DMA was prepared into a dispersion of 0.5 mg / mL using toluene, and its fluorescence intensity at 512 nm was measured using the method of Example 1, as shown in Table 1.

[0116] Table 1 Comparison of fluorescence intensity shows that CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3@TPB-DMA increases with the increase of CsPb 0.7 Mn 0.3 The increase of Br3NCs precursor solution showed a trend of increasing first and then decreasing. 0.7 Mn 0.3 The maximum fluorescence intensity of Br3 NCs precursor solution was 58508 a.u. when the volume was 40 mL. 0.7 Mn 0.3 Br3 NCs precursor solution and the amount of CsPb 0.7 Mn 0.3 The fluorescence intensity of Br3@TPB-DMA is different, so 0.5 g TPB-DMA and 40 mL CsPb 0.7 Mn 0.3 Br3NCs precursor solution is the most ideal COFs type and material ratio.

[0117] Table 1 Different ratios of CsPb 0.7 Mn 0.3 Fluorescence intensity of Br3@TPB-DMA

[0118]

[0119] Example 16, CsPb 0.7 Mn 0.3 Fluorescence detection of 3-MCPD with different concentrations in oils and fats by Br3@TPB-DMA

[0120] 1 mL of soybean oil with different 3-MCPD contents (3-MCPD contents of 0, 1, 10, 20, 50, 100, 500, and 1000 µg / g) was taken respectively, and 1 mg / mL of CsPb prepared by the method of Example 13 was added to each of them. 0.7 Mn 0.3 1 mL of Br3@TPB-DMA toluene dispersion was vortexed for 10 s and allowed to stand at room temperature for 15 min. The fluorescence spectrum was detected using the method in Example 1. Figure 5 shown.

[0121] Figure 5 It can be seen that CsPb 0.7 Mn 0.3 After Br3@TPB-DMA came into contact with soybean oil with different 3-MCPD contents, its characteristic peak position remained basically unchanged (512 nm), but its fluorescence intensity decreased significantly with the increase of 3-MCPD concentration.

[0122] According to the fluorescence spectrum, the characteristic peak position (denoted as λ) and fluorescence intensity (denoted as I) of the control group (3-MCPD content is 0) were recorded. With Lg (3-MCPD content) as the independent variable X and (I0-I) / I0 as the dependent variable Y2, the fluorescence intensity quantitative standard curve Y2=K2X+B2 was constructed by fitting, and K2=0.2127, intercept B2=0.02758, R 2 = 0.9859, showing a good linear relationship ( Figure 6 ), indicating that CsPb 0.7 Mn 0.3 Br3@TPB-DMA fluorescence intensity sensitively detects 3-MCPD in soybean oil.

[0123] Taking Lg (3-MCPD content) as the independent variable X and (λ0-λ) as the dependent variable Y1, the offset quantitative standard curve Y1=K1X+B1 was constructed by fitting, and K1=1.2806, intercept B1=-0.305, R 2 =0.9298, indicating that 3-MCPD can be detected by wavelength shift, but the accuracy and sensitivity of the method are not satisfactory. In addition, the wavelength shift is small, and it is difficult to produce significant color changes ( Figure 7 ), so it is difficult to directly observe CsPb with the naked eye 0.7 Mn 0.3 Br3@TPB-DMA color change for sensitive detection of 3-MCPD in soybean oil.

[0124] The decrease in fluorescence intensity is mostly due to the destruction of CsPb by polar substances. 0.7 Mn 0.3 Br3@TPB-DMA structure leads to the conclusion that CsPb0.7 Mn 0.3 The Br3@TPB-DMA structure is easily affected by other substances; while CsPb 0.7 Mn 0.3 The wavelength shift of Br3@TPB-DMA is mostly due to changes in composition, which proves that the CsPb 0.7 Mn 0.3 Br3@TPB-DMA has high specificity. Therefore, if the decrease in fluorescence intensity and wavelength shift can be analyzed comprehensively, the 3-MCPD content will be detected more accurately.

[0125] Example 17: Activation of 3-MCPD and CsPb by Copper Oxide 0.7 Mn 0.3 Wavelength shift of Br3@TPB-DMA reaction products

[0126] 10 mL of soybean oil (3-MCPD content of 100 and 4000 µg / g) was taken respectively, 0.1 g of copper oxide was added, vortexed for 10 seconds and centrifuged, 1 mL of the supernatant was taken, and 1 mg / mL of CsPb prepared by the method of Example 13 was added. 0.7 Mn 0.3 1 mL of Br3@TPB-DMA toluene dispersion was vortexed for 10 s and allowed to stand at room temperature for 15 min. The fluorescence spectrum was measured using the method in Example 1 to determine the position of the characteristic peak and calculate the wavelength shift compared with the 512 nm characteristic peak, as shown in Table 2.

[0127] Example 18, Palladium-carbon activation of 3-MCPD and CsPb 0.7 Mn 0.3 Wavelength shift of Br3@TPB-DMA reaction products

[0128] 10 mL of soybean oil (3-MCPD content of 100 and 4000 µg / g) was taken respectively, and 0.1 g of palladium carbon (palladium content of 10%) was added. After vortexing for 10 s, centrifugation was performed, and 1 mL of the supernatant was taken. 1 mg / mL of CsPb prepared by the method of Example 13 was added. 0.7 Mn 0.3 1 mL of Br3@TPB-DMA toluene dispersion was vortexed for 10 s and allowed to stand at room temperature for 15 min. The fluorescence spectrum was measured using the method in Example 1 to determine the position of the characteristic peak and calculate the wavelength shift compared with the 512 nm characteristic peak, as shown in Table 2.

[0129] Control group: 1 mL soybean oil (3-MCPD content of 100 and 4000 µg / g) was taken and 1 mg / mL CsPb prepared by the method of Example 13 was added. 0.7 Mn 0.31 mL of Br3@TPB-DMA toluene dispersion was vortexed for 10 s and allowed to stand at room temperature for 6 h. The fluorescence spectrum was measured using the method of Example 1 to determine the characteristic peak wavelength shift, as shown in Table 2.

[0130] Table 2 shows that after the palladium carbon catalyst treatment, CsPb 0.7 Mn 0.3 The wavelength shift of Br3@TPB-DMA is significantly higher than that of the copper oxide catalyst treatment and the control group. The greater the wavelength shift, the higher the sensitivity and accuracy of the measurement. At the same time, the palladium carbon mild environment (room temperature and natural light) treatment has good stability, strong adaptability, and good repeatability. Therefore, the palladium carbon activation treatment can be used to determine the 3-MCPD content by detecting the fluorescence peak shift, which significantly improves the sensitivity, accuracy and detection limit of the detection, and greatly reduces the detection time.

[0131] Table 2 3-MCPD and CsPb after activation with palladium carbon and copper oxide 0.7 Mn 0.3 The maximum fluorescence absorption wavelength shift of the Br3@TPB-DMA reaction product

[0132]

[0133] Example 19: CsPb under palladium carbon pretreatment 0.7 Mn 0.3 Fluorescence response of Br3@TPB-DMA to 3-MCPD in oils and fats

[0134] 10 mL of soybean oil with different 3-MCPD contents (3-MCPD contents of 0, 1, 10, 100, 500, 1000, 2000, and 4000 µg / g) was taken respectively, 0.1 g of palladium carbon was added, vortexed for 10 s and centrifuged, 1 ml of the supernatant was taken, and 1 mg / mL of CsPb prepared by the method of Example 13 was added to each of the 10 mL of soybean oil with different 3-MCPD contents (3-MCPD contents of 0, 1, 10, 100, 500, 1000, 2000, and 4000 µg / g) was added, 10 g of palladium carbon was added, vortexed for 10 s and centrifuged, 1 ml of the supernatant was taken, and 1 mg / mL of CsPb prepared by the method of Example 13 was added to each of the 10 mL of soybean oil with different 3-MCPD contents (3-MCPD contents of 0, 1, 10, 100, 500, 1000, 2000, and 4000 µg / g) was added to each of the 10 mL of soybean oil with different 3-MCPD contents (3-MCPD contents of 0, 1, 10 0.7 Mn 0.3 1 mL of Br3@TPB-DMA toluene dispersion was vortexed for 10 s and allowed to stand at room temperature for 15 min. The fluorescence spectrum was detected using the method in Example 1.

[0135] Under 365 nm UV light, soybean oil with different 3-MCPD contents and CsPb were photographed. 0.7 Mn 0.3 Photos of Br3@TPB-DMA reactants, such as Fig.11 shown.

[0136] Fluorescence spectra such as Figure 8 It can be seen that after palladium carbon treatment, CsPb 0.7 Mn 0.3After Br3@TPB-DMA reacted with different concentrations of 3-MCPD, as the concentration of 3-MCPD increased, its characteristic peak position shifted significantly to the blue, and its fluorescence intensity decreased significantly.

[0137] According to the fluorescence spectrum, the characteristic peak position (denoted as λ) and fluorescence intensity (denoted as I) of the 3-MCPD reactant at different concentrations were recorded, and the characteristic peak position (denoted as λ0) and fluorescence intensity (denoted as I0) of the control group (3-MCPD content was 0) were recorded. With Lg (3-MCPD content) as the independent variable X and (λ0-λ) as the dependent variable Y1, the offset quantitative standard curve Y1=K1X+B1 was constructed by fitting, and K1=3.8726, intercept B1 was -0.06, and R 2 =0.9748, and its detection limit is 1 µg / g ( Fig.10 ).

[0138] With Lg (3-MCPD content) as the horizontal coordinate X and (I0-I) / I0 as the vertical coordinate Y2, the fluorescence intensity quantitative standard curve Y2=K2X+B2 was constructed by fitting, and K2=0.1162, intercept B2=0.2627, R 2 = 0.9903, showing a good linear relationship ( Fig. 9 ), with a detection limit of 0.274 µg / g.

[0139] Based on CsPb 0.7 Mn 0.3 The wavelength of Br3@TPB-DMA is shifted to obtain its reaction photos. Fig.11 The difference can be distinguished by naked eye.

[0140] Example 20, CsPb 0.7 Mn 0.3 Detection of 3-MCPD in different edible oils by Br3@TPB-DMA

[0141] Commercially available camellia oil, olive oil, linseed oil, soybean oil, walnut oil, sesame oil, gardenia oil, and Torreya grandis oil were selected as the samples to be tested, and the amount of 3-MCPD added was 10 μg / g. The subsequent operation was the same as in Example 19. According to the standard curve of Example 19, the 3-MCPD content in the samples to be tested was obtained, and the results are shown in Table 3.

[0142] The results in Table 3 show that the CsPb 0.7 Mn 0.3Br3@TPB-DMA is suitable for 3-MCPD detection of various edible oils. In the wavelength shift method, the error of the detection results compared with the spiked recovery samples was between 1.3-13.8%, and the average error was 8.68%; in the fluorescence intensity reduction method, the error of the detection results compared with the spiked recovery samples was between 2.2-9.5%, and the average error was 6.29%. This reflects the higher accuracy, sensitivity and lower detection limit of the new method. In particular, the method is simple, fast, and the results are intuitive, which is particularly suitable for rapid on-site detection.

[0143] Table 3 CsPb 0.7 Mn 0.3 Determination of 3-MCPD in different edible oils by Br3@TPB-DMA method

[0144]

Claims

1. A method for rapid detection of 3-chloropropanol in edible oil using a manganese ion-doped perovskite nanocrystal composite, characterized in that: The preparation method of the composite is to crystallize and grow a Pb-Cs stock solution and a Mn-Cs stock solution used for preparing perovskite nanocrystals doped with manganese ions in a COFs material to prepare the composite; Pb-Cs stock solution: PbBr2 and CsBr were weighed, mixed and dispersed in N,N-dimethylformamide, and stirred until the solid was completely dissolved to prepare a Pb-Cs stock solution; Mn-Cs stock solution: Weigh MnBr2 and CsBr, mix and disperse in N,N-dimethylformamide, and stir until the solid is completely dissolved to prepare a Mn-Cs stock solution; The molecular formula of the manganese ion-doped perovskite nanocrystal is CsPb (1-x) Mn x Br3, x is 0.1, 0.2, 0.3, 0.4 or 0.5; The COFs material includes 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, or 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinylterephthalaldehyde covalently connected.

2. The method according to claim 1, characterized in that The concentrations of PbBr2 and CsBr in the Pb-Cs stock solution were both 0.04 mol / L, and the concentrations of MnBr2 and CsBr in the Mn-Cs stock solution were both 0.04 mol / L.

3. The method according to claim 1, characterized in that The method is carried out according to the following steps: ultrasonically mixing the Pb-Cs stock solution, the Mn-Cs stock solution and the COFs material for 1-3 minutes, stirring for 1-3 hours, adding oleic acid and oleylamine, stirring for 5-15 minutes, adding toluene, stirring for 1-3 minutes, centrifuging, taking the precipitate and drying it to obtain the composite.

4. The method according to claim 3, characterized in that The amount of the Pb-Cs stock solution is calculated based on the amount of the Pb substance, the amount of the Mn-Cs stock solution is calculated based on the amount of the Mn substance, and the molar ratio of the Pb to the Mn is 9:1-1:

1.

5. The method according to claim 3, characterized in that The volume ratio of oleic acid to oleylamine is 1:1, and the ratio of the total volume of oleic acid and oleylamine to the total volume of Pb-Cs stock solution and Mn-Cs stock solution is 0.1:1; the ratio of the volume of toluene to the total volume of Pb-Cs stock solution and Mn-Cs stock solution is 20:1; the ratio of the mass of the COFs material to the total volume of the Pb-Cs stock solution and the Mn-Cs stock solution is 0.5 g:40-100 mL.

6. The method according to claim 1, characterized in that The method comprises: adding palladium carbon to the edible oil to be tested, vortexing for 5-15 seconds, centrifuging, taking the upper clear liquid and adding it to a toluene dispersion of a perovskite nanocrystal complex doped with manganese ions, vortexing for 5-15 seconds, standing at room temperature for 10-30 minutes, and detecting a 400-700 nm fluorescence spectrum; calculating the 3-chloropropanol content in the edible oil to be tested according to a characteristic peak fluorescence intensity or a characteristic peak offset value, a standard curve of the characteristic peak fluorescence intensity and the 3-chloropropanol concentration, or a standard curve of the characteristic peak offset value and the 3-chloropropanol concentration; The standard curve of the fluorescence intensity of the characteristic peak and the concentration of 3-chloropropanol or the standard curve of the characteristic peak offset value and the concentration of 3-chloropropanol was prepared as follows: Take soybean oil with different 3-chloropropanol contents, add palladium carbon, vortex for 5-15 seconds, and centrifuge; take the upper clear liquid, add toluene dispersion of perovskite nanocrystal complex doped with manganese ions, vortex for 5-15 seconds, stand at room temperature for 10-30 minutes, and detect the fluorescence spectrum at 400-700nm; the 3-chloropropanol contents are 1, 10, 100, 500, 1000, 2000, and 4000 µg / g respectively; the 3-chloropropanol content of 0 is used as the control group; The characteristic peak position of different 3-chloropropanol contents was recorded as λ, and the fluorescence intensity was recorded as I; the characteristic peak position of the control group was recorded as λ0, and the fluorescence intensity was recorded as I0; the Lg value of 3-chloropropanol content was used as the horizontal coordinate and (λ0-λ) as the vertical coordinate, and the offset quantitative standard curve was constructed by fitting; The fluorescence intensity quantitative standard curve was constructed by fitting, with the Lg value of 3-chloropropanol content as the horizontal axis and (I0-I) / I0 as the vertical axis.

7. The method according to claim 6, characterized in that The amount of palladium carbon added is 5-15 mg / mL; the concentration of the toluene dispersion of the manganese ion-doped perovskite nanocrystal complex is 1-5 mg / mL, and the volume ratio of the added amount to the supernatant is 1-3:1.

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