A fluorescence sensing array detection platform and detection method for multiple plasticizers

Abstract

The present invention combines a fluorescence sensor with an array to provide a fluorescence sensing array detection platform and a detection method for multiple plasticizers. The fluorescence sensing array detection platform includes a B-doped graphene quantum dot solution using N,N-dimethylformamide as a solvent and a B-GQDs solution using cyclohexane as a solvent; the fluorescence intensity of the B-GQDs solution with DMF as the solvent at the fluorescence characteristic peak obtained under ultraviolet light excitation at a wavelength of 350 nm, and the fluorescence data at 391 nm, 413 nm, and 434 nm are used as array points 1, 2, and 3; the fluorescence intensity of the B-GQDs solution with CH as the solvent at the fluorescence characteristic peak obtained under ultraviolet light excitation at a wavelength of 350 nm, and the fluorescence data at 386 nm, 408 nm, and 430 nm are used as array points 4, 5, and 6; thus, a 3×2 fluorescence sensor array is constructed. The detection method using the fluorescence sensor array of the present invention has simple steps, and has satisfactory specificity, reproducibility, stability and practicability, and has application potential.

Description

Technical Field

[0001] The present invention relates to the detection of plasticizers, and particularly to a fluorescence sensing array detection platform and detection method for multiple plasticizers. Background Art

[0002] Phthalic acid esters (PAEs) are plasticizers that enhance the performance of products such as plastics and rubbers. Therefore, PAEs are mass-produced in the industry. The wanton increase and widespread presence of PAEs are gradually threatening human health and the public environment. PAEs have estrogen-like effects, hepatotoxicity, and nephrotoxicity, and may cause negative effects such as cell metabolic disorders and cardiovascular system imbalance. For the detection of PAEs, common methods include high performance liquid chromatography, gas chromatography, gas chromatography-mass spectrometry, infrared spectroscopy, surface-enhanced Raman scattering spectroscopy, etc. They are usually large instruments, expensive, and complex to operate. More specifically, the matrix effect and co-eluting substances in the separation of high performance liquid chromatography and gas chromatography will change the ionization efficiency of the components to be detected, which will cause signal interference; compared with conventional and traditional detection methods, infrared spectroscopy has no obvious advantage in detection sensitivity and cannot be applied to the detection of water-containing samples; surface-enhanced Raman scattering spectroscopy uses metal nanomaterials such as gold and silver as substrates. Under the excitation of light, local surface plasmon resonance (hot spots) will be generated. When the substance to be detected is placed at the hot spots, an enhanced Raman signal of the substance to be detected will be obtained, which has high sensitivity, but it has the disadvantages of being easily interfered and polluted. The above methods are all complex and not convenient for effective analysis, and usually need to extract effective data from the accumulated information, which is both time-consuming and laborious. Therefore, it is urgent to find a fast, sensitive, efficient, and low-cost detection method.

[0003] In the context of the booming development of chemical sensing technology, there are a wide variety of available sensors. Among them, the fluorescence sensor, as an optical sensor, is an important detection tool that can achieve rapid and specific targeting of the target. It usually has high sensitivity, strong anti-interference ability, and can cope with complex detection environments. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention combines a fluorescence sensor with an array to provide a fluorescence sensing array detection platform and detection method for multiple plasticizers.

[0005] The described fluorescence sensing array detection platform includes a B-doped graphene quantum dot (B-GQDs) solution using N,N-dimethylformamide (DMF) as a solvent and a B-doped graphene quantum dot (B-GQDs) solution using cyclohexane (CH) as a solvent; the fluorescence intensity of the B-GQDs solution with DMF as the solvent at the fluorescence characteristic peak obtained under ultraviolet light excitation at a wavelength of 350 nm, and the fluorescence data at 391 nm, 413 nm, and 434 nm are used as array points 1, 2, and 3; the fluorescence intensity of the B-GQDs solution with CH as the solvent at the fluorescence characteristic peak obtained under ultraviolet light excitation at a wavelength of 350 nm, and the fluorescence data at 386 nm, 408 nm, and 430 nm are used as array points 4, 5, and 6; thus, a 3×2 fluorescence sensor array is constructed. The described fluorescence intensity (ΔF) is the response value of this fluorescence sensing array, and ΔF = |F before reaction - F after reaction|.

[0006] The preparation method of the described B-doped graphene quantum dot (B-GQDs) is as follows:

[0007] Take a certain amount of 1,3,6-trinitropyrene and boric acid and uniformly disperse them in N,N-dimethylformamide (DMF) to prepare a mixed solution with a mass concentration of 60 g / L, where the mass ratio of 1,3,6-trinitropyrene to boric acid is 2:1. Transfer the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining and react at 180 °C for 12 hours. The liquid after the reaction is the B-doped graphene quantum dot (B-GQDs) solution. Filter it through a 0.22-micron filter membrane to remove impurities, and then store it at 4 °C.

[0008] Based on the fluorescence sensing array detection platform provided above, a fluorescence sensing array detection method for various plasticizers provided by the present invention is as follows:

[0009] Dilute 5 μL of the B-GQDs solution to 10 mL with two solvents, DMF and CH, respectively, to prepare a B-GQDs stock solution with DMF as the solvent and a B-GQDs stock solution with CH as the solvent.

[0010] Prepare sample solutions of the plasticizer samples to be measured with two solvents, DMF and CH, respectively.

[0011] Mix 20 μL of the B-GQDs stock solution with DMF as the solvent and 400 μL of the sample solution with DMF as the solvent under ultraviolet light excitation at a wavelength of 350 nm to obtain the fluorescence intensity of the fluorescence characteristic peak, and take the fluorescence data at array points 1, 2, and 3, namely 391 nm, 413 nm, and 434 nm; Mix 20 μL of the B-GQDs stock solution with CH as the solvent and 400 μL of the sample solution with CH as the solvent under ultraviolet light excitation at a wavelength of 350 nm to obtain the fluorescence intensity of the fluorescence characteristic peak, and take the fluorescence data at array points 4, 5, and 6, namely 386 nm, 408 nm, and 430 nm.

[0012] After obtaining the data of the six array points, perform linear fitting on the data of each array point, and select the array point with the strongest correlation in the fitting result as the advantageous point for the quantitative detection of this plasticizer.

[0013] The plasticizers detected by the detection method of the present invention include: diisobutyl phthalate (DIBP), bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), diallyl phthalate (DAP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP).

[0014] Advantages of the present invention:

[0015] The present invention selects the one-pot solvothermal method to synthesize B-GQDs with high fluorescence intensity. According to the number of fluorescence characteristic peaks and solvents, six array points are constructed. The fluorescence sensor array of the present invention can effectively detect six plasticizers. The fluorescence information output by the fluorescence sensor array shows a good linear relationship with the concentrations of the six plasticizers. The quantitative detection ability can be specifically described as: the detection range is 100 ng / mL - 195 ng / mL, the detection limit is 1.05 - 11.58 ng / mL, and it shows good analytical performance in actual samples, with a recovery rate of 95% - 106%. The detection method using the fluorescence sensor array in the present invention has simple steps and low experimental operation requirements. After simply dissolving the sample containing the plasticizer with DMF and CH, and then introducing a very small amount of B-GQDs, multi-dimensional detection of the plasticizer can be achieved at six array points. This method has satisfactory specificity, reproducibility, stability, and practicality, and has application potential. Description of the Drawings

[0016] Figure 1 It is the fluorescence spectrogram of the dissolution of B-GQDs of the present invention in DMF and CH;

[0017] Figure 2 It is the characterization of B-GQDs of the present invention;

[0018] Figures (a-b) are TEM micrographs of B-GQDs; (c) is the FT-IR spectrum of B-GQDs; (d) is the Survey-scan XPS spectrum of B-GQDs; XPS spectra of B-GQDs: (e) is O1s, (f) is N1s, (g) is C1s, (h) is B1s;

[0019] Figure 3 Reactions of B-GQDs of the present invention dispersed in (a) DMF and (b) CH with plasticizer-5 series concentrations; Selectivity of B-GQDs dispersed in (c) DMF and (d) CH to plasticizer-5.

[0020] Figure 4 Schematic diagram of the quantitative detection experiment of six plasticizers by array points 1 to 6 of the present invention;

[0021] (a) is plasticizer 6; (b) is plasticizer 5; (c) is plasticizer 4; (d) is plasticizer 2; (e) is plasticizer 3; (f) is plasticizer 1;

[0022] Figure 5 Schematic diagram of the specificity experiment of the fluorescence sensor array of the present invention;

[0023] Figure 6 Schematic diagram of the stability and lifetime experiments of the fluorescence sensor array of the present invention. (a) is array point 1; (b) is array point 2; (c) is array point 3; (d) is array point 4; (e) is array point 5; (f) is array point 6. Detailed implementation manners

[0024] A fluorescence sensing array detection platform for multiple plasticizers provided in this embodiment is prepared as follows:

[0025] First, dissolve 2 grams of pyrene in 240 mL of concentrated nitric acid with a concentration of 16 mol / L, continuously stir at 80 °C, and carry out nitrification for 18 hours. To stabilize the nitro group, then cool the mixture to 25 °C and dilute it with 2 L of deionized water. After stirring the diluted solution for 24 hours, filter it and dry it at 60 °C for 24 hours. 1,3,6-trinitropyrene is obtained in this step.

[0026] Take 2 grams of 1,3,6-trinitropyrene and 1 gram of boric acid and uniformly disperse them in 50 mL of N,N-dimethylformamide (DMF) to prepare a mixed solution. Transfer the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining and react at 180 °C for 12 hours. The liquid after the reaction is the solution of B-doped graphene quantum dots (B-GQDs). Remove impurities through a 0.22-micron filter membrane and then store it at 4 °C.

[0027] Solutions of B-doped graphene quantum dots (B-GQDs) using N,N-dimethylformamide (DMF) as a solvent and solutions of B-doped graphene quantum dots (B-GQDs) using cyclohexane (CH) as a solvent; the fluorescence intensity of the B-GQDs solution with DMF as the solvent to obtain a fluorescence characteristic peak under ultraviolet light excitation at a wavelength of 350 nm, taking the fluorescence data at 391 nm, 413 nm, and 434 nm as array points 1, 2, and 3; the fluorescence intensity of the B-GQDs solution with CH as the solvent to obtain a fluorescence characteristic peak under ultraviolet light excitation at a wavelength of 350 nm, taking the fluorescence data at 386 nm, 408 nm, and 430 nm as array points 4, 5, and 6; thus, a 3×2 fluorescence sensor array is constructed.

[0028] A fluorescence sensing array detection method for multiple plasticizers provided in this embodiment includes the following steps:

[0029] Dilute 5 μL of the B-GQDs solution to 10 mL with two solvents, DMF and CH respectively, to prepare a B-GQDs stock solution with DMF as the solvent and a B-GQDs stock solution with CH as the solvent.

[0030] Dilute 100 μL of the plasticizer-containing sample (or interference / real sample) to 1 mL with two solvents, DMF and CH respectively, to prepare a sample solution with DMF as the solvent and a sample solution with CH as the solvent. In this embodiment, the plasticizer samples include: plasticizer 1 - diisobutyl phthalate (DIBP), plasticizer 2 - bis(2-ethylhexyl) phthalate (DEHP), plasticizer 3 - dibutyl phthalate (DBP), plasticizer 4 - diallyl phthalate (DAP), plasticizer 5 - diisononyl phthalate (DINP), plasticizer 6 - diisodecyl phthalate (DIDP), and the interfering substances are tetrahydrofuran, dichloromethane, ethyl acetate, and styrene respectively.

[0031] Mix 20 μL of the B-GQDs stock solution with DMF as the solvent and 400 μL of the sample solution with DMF as the solvent under ultraviolet light excitation at a wavelength of 350 nm to obtain the fluorescence intensity of the fluorescence characteristic peak, and take the fluorescence data at array points 1, 2, and 3, namely 391 nm, 413 nm, and 434 nm; mix 20 μL of the B-GQDs stock solution with CH as the solvent and 400 μL of the sample solution with CH as the solvent under ultraviolet light excitation at a wavelength of 350 nm to obtain the fluorescence intensity of the fluorescence characteristic peak, and take the fluorescence data at array points 4, 5, and 6, namely 386 nm, 408 nm, and 430 nm.

[0032] After obtaining the data of the six array points, perform linear fitting on the data of each array point, and select the array point with the strongest correlation of the fitting result as the dominant point for the quantitative detection of this plasticizer.

[0033] Working principle of the present invention:

[0034] Due to the interaction between B and graphene quantum dots, boron-doped graphene quantum dots and graphene quantum dots with the same concentration, the former has stronger fluorescence properties. Therefore, doping boron in graphene quantum dots can provide a wider response range for sensing detection. Boron-doped graphene quantum dots have three characteristic emission regions in both DMF or CH, specifically: (a) 350 - 400 nm, π→π*, C=C transition, (b) 400 - 430 nm, n→π*, C=O and C=N transitions, (c) 430 - 460 nm, n→π*, transitions of non-bonding electrons such as B-C, C-O, B-O, N-B, C-NO2. DMF is called the "universal solvent" because it can dissolve most organic and inorganic compounds, with a relative polarity of 0.386. CH is a saturated compound and is not easily reactive with other substances at room temperature. The polarity of CH is very different from that of DMF, with a relative polarity of 0.006. DMF and CH are selected as solvents because they have different polarities and saturation levels. Most importantly, the dispersibility of boron-doped graphene quantum dots in the two solvents leads to different fluorescence signals. Under ultraviolet light, the suspension of boron-doped graphene quantum dots in DMF is blue-violet, while the suspension in CH is bright yellow. Benefiting from the fact that boron-doped graphene quantum dots have three characteristic fluorescence emission peaks( Figure 1 ), their solvent dependence results in the shift of the characteristic peak positions. 391, 413, and 434 nm are sequentially selected as array points 1, 2, and 3 (DMF as the solvent). 386, 408, and 430 nm are respectively regarded as array points 4, 5, and 6 (CH as the solvent). The suspensions in DMF and CH show good dispersibility, which in turn directly affects the fluorescence properties. Solvent molecules with different physicochemical properties change the interfacial structure (such as local defects and chemical bonds) between the surfaces of boron-doped graphene quantum dots. When the analyte is reintroduced, the interfacial structure changes again, and the dispersion reaches a new equilibrium. In addition, there are other factors in the analyte that affect the fluorescence characteristics of boron-doped graphene quantum dots. For example, the carbonyl group in the plasticizer has an electron-withdrawing effect. It can accept electrons from the excited state to generate photoinduced electron transfer and cause fluorescence quenching. In summary, dispersibility and electron transfer directly affect the fluorescence characteristics of boron-doped graphene quantum dots.

[0035] Transmission electron microscopy (TEM) is used to observe the morphology of B-GQDs. As Figure 2 (a-b) shows, the prepared B-GQDs are overall uniformly dispersed and spherical. Its particle size distribution diagram shows a normal distribution centered at 2 - 4 nanometers, with an average particle size of 3 nanometers. Fourier transform infrared spectrometer (FT-IR) is used to confirm the functional groups attached to B-GQDs. From Figure 2(c) It can be seen that the sample contains carboxyl groups because the C-O stretching of carboxyl groups was found at 1000 - 1200 cm -1 -1, and the peak corresponding to 1650 cm also shows the presence of C═C and C═N; most importantly, the stretching at 1080 cm -1 and 1390 cm -1 correspond to the stretching of C-B and B-O respectively, which confirms the successful incorporation of boron into GQDs. X-ray photoelectron spectroscopy (XPS) can provide information such as elemental composition and content, molecular structure, chemical bonds, etc., Figure 2 (d) is the survey scan XPS spectrum of B-GQDs. C1s (284.21 eV), N1s (405.21 eV), O1s (532.07 eV), and B1s (188.03 eV) are its four main elements, and their atomic contents are 72.95%, 15.41%, 8.16%, and 3.49% in sequence. Figure 2 (e - h) are the high-resolution O1s, N1s, C1s, and B1s peaks of B-GQDs. The peaks of the O1s spectrum are composed of C═O and C-O / B-O / C-NO2. C-NO2 is one of the factors affecting the dispersion performance of B-GQDs; the N1s spectrum consists of the following components: N-B, graphitic N, pyridine / pyrroline N, and NO2, corresponding to 398.82 eV, 401.46 eV, 403.88 eV, and 405.47 eV respectively; according to the bond type of C atoms, the C1s spectrum can be decomposed into four peaks: C-O (285.3 eV), C═O / C-C (284.5 eV), C-B (283.8 eV); the presence of the C-B group indicates the doping of boron in the graphite lattice. Moreover, the peak of B1s is supported by B-N (187.8 eV), B-C (188.8 eV), BC2O (189.3 eV), and BCO2 (190.5 eV). It can also be inferred therefrom that boron atoms have been successfully incorporated into the framework of graphene quantum dots, confirming the successful preparation of B-GQDs.

[0036] The present invention conducts a responsiveness test on a sensor array platform for five concentrations of plasticizer 5 (0, 0.3, 1.6, 8.0, 40.0 mg / mL). Figure 3 (a) is the fluorescence spectrum obtained using DMF as a solvent. Figure 3 (b) shows using CH as a solvent. They show that the quenching ability of plasticizer - 5 decreases simultaneously from high concentration to low concentration. In Figure 3 (c - d), in the face of four interfering substances (tetrahydrofuran, dichloromethane, ethyl acetate, and styrene), the fluorescence intensity of B-GQDs is hardly affected. This indicates that the effect of plasticizer on B-GQDs is specific, proving the feasibility of the present invention.

[0037] Figure 4 Six phthalates were quantitatively detected from array points 1 to 6. For these six phthalates, the lowest limit of detection (LOD) was 1.05 ng / mL and the highest LOD was 11.58 ng / mL.

[0038] As shown in Table 1, the present invention compared the fluorescence sensor array with other detection methods for phthalates. The fluorescence sensing array established in the present invention has a wide detection range and a low detection limit. Compared with other detection methods for phthalates, the present invention does not require expensive antigen-antibody, nor the cumbersome processes of precisely preparing template molecules and layer-by-layer modification of electrodes, and has the advantages of convenience, low cost and high sensitivity.

[0039] Table 1 Comparison with other detection methods

[0040]

[0041] As Figure 5 shown, the present invention selected more than 20 interfering substances to explore the fluorescence sensor array. The concentrations of these interfering substances were 10 times that of the phthalates. Taking array point 1 as an example, the response values of the phthalate and the fluorescence sensing array were 4.8 - 57 times that of the interfering substances. This verified that the fluorescence sensing array has good specificity in detection.

[0042] As Figure 6 shown, the present invention further examined the stability and lifespan of the fluorescence sensor array through 20 consecutive days of testing. The fluorescence values after the reaction of all array points were summarized: on the 7th day, the fluorescence intensity decayed to 90% of the initial value, on the 13th day, it decayed to 80% of the initial value, and on the 20th day, it decayed to 70% of the initial value. Generally speaking, the fluorescence sensor array of the present invention has good stability. To ensure the correctness and reliability of the detection results, the lifespan of the fluorescence sensing array of the present invention is about 13 days.

[0043] The packaging containers of medical disinfection alcohol (MDA) are generally made of plastic, and it is very likely that plasticizers will penetrate into MDA, which will provide an opportunity for plasticizers to come into direct contact with human skin. To further evaluate the practicality of the present invention, MDA was selected as the actual sample in this example, and the concentrations of plasticizers 1-6 were determined by the standard addition method. Plasticizer 5 has a relatively large molecular weight and many isomers, which easily interfere with the reaction results of the sensor. Therefore, it was selected as a special case for the analysis of real samples. Specifically, the retention time of plasticizer 5 is 19.526 minutes, its qualitative ions are 77, 133, 163, and 194 (m / z), and the quantitative ion is 163 (m / z). Table 2 lists the recovery rates of plasticizer 5 under the two detection methods of the present invention and GC-MS, ranging from 95% to 106%, and the RSD is 1% to 9%. The above situation indicates that the sensor array has good application prospects in the detection of plasticizers.

[0044] Table 2 Spike recovery experiment of plasticizer-5

[0045]

Claims

1. A fluorescence sensing array detection platform for multiple plasticizers, characterized in that: The described fluorescence sensing array detection platform includes a B-doped graphene quantum dot (B-GQDs) solution using N,N-dimethylformamide (DMF) as a solvent and a B-GQDs solution using cyclohexane (CH) as a solvent. The fluorescence intensity of the B-GQDs solution with DMF as the solvent at the fluorescence characteristic peak obtained under ultraviolet light excitation at a wavelength of 350 nm is used. The fluorescence data at 391 nm, 413 nm, and 434 nm are taken as array points 1, 2, and 3. The fluorescence intensity of the B-GQDs solution with CH as the solvent at the fluorescence characteristic peak obtained under ultraviolet light excitation at a wavelength of 350 nm is used. The fluorescence data at 386 nm, 408 nm, and 430 nm are taken as array points 4, 5, and 6. A 3×2 fluorescence sensor array is constructed. The plasticizers for detection include one or several of diisobutyl phthalate (DIBP), bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), diallyl phthalate (DAP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP).

2. The fluorescence sensing array detection platform for multiple plasticizers according to claim 1, characterized in that: The preparation method of the described B-doped graphene quantum dots (B-GQDs) is as follows: Take a certain amount of 1,3,6-trinitropyrene and boric acid and uniformly disperse them in N,N-dimethylformamide (DMF) to prepare a mixed solution with a mass concentration of 60 g / L, where the mass ratio of 1,3,6-trinitropyrene to boric acid is 2:

1. Transfer the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene lining and react at 180 °C for 12 hours. The reacted liquid is the B-GQDs solution, and impurities are removed through a 0.22-micron filter membrane.

3. A fluorescence sensing array detection method for multiple plasticizers, characterized in that: Based on the fluorescence sensing array detection platform described in claim 1 or 2, dilute 5 μL of the B-GQDs solution to 10 mL with two solvents, DMF and CH, respectively, to prepare a B-GQDs stock solution with DMF as the solvent and a B-GQDs stock solution with CH as the solvent. Prepare sample solutions of the plasticizer samples to be detected with two solvents, DMF and CH, respectively. Mix 20 μL of the B-GQDs stock solution with DMF as the solvent and 400 μL of the sample solution with DMF as the solvent under ultraviolet light excitation at a wavelength of 350 nm to obtain the fluorescence intensity at the fluorescence characteristic peak, and take the fluorescence data at array points 1, 2, and 3, namely 391 nm, 413 nm, and 434 nm. Mix 20 μL of the B-GQDs stock solution with CH as the solvent and 400 μL of the sample solution with CH as the solvent under ultraviolet light excitation at a wavelength of 350 nm to obtain the fluorescence intensity at the fluorescence characteristic peak, and take the fluorescence data at array points 4, 5, and 6, namely 386 nm, 408 nm, and 430 nm. After obtaining the data of the six array points, perform linear fitting on the data of each array point, and select the array point with the strongest correlation in the fitting result as the advantageous point for quantitative detection of the plasticizer.

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