CN109187507B - Electrochemiluminescence sensor for detecting bisphenol A and preparation method and application thereof - Google Patents
Electrochemiluminescence sensor for detecting bisphenol A and preparation method and application thereof Download PDFInfo
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- CN109187507B CN109187507B CN201810666793.9A CN201810666793A CN109187507B CN 109187507 B CN109187507 B CN 109187507B CN 201810666793 A CN201810666793 A CN 201810666793A CN 109187507 B CN109187507 B CN 109187507B
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Abstract
The invention discloses an electrochemiluminescence sensor for detecting bisphenol A and a preparation method thereof3O4The modification layer of the nanocrystal consists of perfluorosulfonic acid modified on the surface of the composite layer, and the electrochemiluminescence sensor for detecting bisphenol A is constructed by taking alkaline luminol solution as electrolyte, wherein the preparation method comprises the step of Fe3O4Preparing nano crystals; mixing Fe3O4Sequentially dripping NCs solution and perfluorosulfonic acid ethanol solution on the surface of the glassy carbon electrode to obtain a working electrode Nafion/Fe3O4NCs/GCE, namely an electrochemiluminescence sensor for detecting bisphenol A, has the advantages of good selectivity, stability and high sensitivity.
Description
Technical Field
The invention belongs to the technical field of novel nanometer functional materials and biosensors, and particularly relates to an electrochemiluminescence sensor for detecting bisphenol A, and a preparation method and application thereof.
Background
Bisphenol a, namely 4, 4-dihydroxydiphenyl propane (BPA for short), is an environmental Endocrine Disrupting Chemicals (EDCs) with estrogenic activity, and causes serious pollution and harm to the ecological environment. Bisphenol A is one of the most widely used industrial compounds in the world, and is mainly used for producing various high polymer materials such as polycarbonate, epoxy resin, rubber anti-aging agent, coating and the like and fine chemical products. The addition of bisphenol A can enable plastic products to have the characteristics of colorless transparency, durability, lightness, good impact resistance and the like, so the bisphenol A is widely applied to the manufacture of common daily necessities such as packages of canned food and beverage, sealing glue for milk bottles, water cups, tooth fillers, spectacle lenses and the like. Bisphenol A precipitates and migrates under conditions of heat, sunlight, etc. Animal experiments show that the bisphenol A has the effect of estrogen-like, and the low dosage can also enable the animals to have the effects of female prematurity, reduction of the number of male sperms, prostate growth and the like. In addition, the data show that bisphenol A has certain embryotoxicity and teratogenicity, and can obviously increase the occurrence of cancers such as animal ovarian cancer, prostatic cancer, leukemia and the like. Studies have shown that BPA is orally administered in half the Lethal Dose (LD) in rat model experiments50) 3250.0 mg/kg; in the mouse model experiment, the oral half lethal dose is 2400.0 mg/kg. The limit for BPA intake in humans is 1.0. mu.g/kg. Based on the serious harm effect of BPA to human body, the development has important practical significance to the detection and monitoring technology.
At present, detection methods related to bisphenol A mainly focus on gas chromatography, gas-mass spectrometry, liquid chromatography, liquid-mass spectrometry, DNA aptamer methods, immunochromatography, capillary electrophoresis and the like, although the methods have high sensitivity and high accuracy, complicated pretreatment needs to be carried out on a sample to be detected, required instruments are expensive, large and heavy, professional technicians are required to carry out daily maintenance, and the defects of long time consumption, high cost, inapplicability to field detection and the like exist. In view of the serious human and ecological environment damage caused by bisphenol A and the limitation of the current detection technology, the development of the technology for detecting bisphenol A is necessary. The electrochemiluminescence analysis technology is widely applied to the fields of clinical diagnosis, drug analysis, environmental monitoring and the like due to the advantages of small background interference, high sensitivity, wide linear range, simple and convenient operation and the like, but the existing electrochemiluminescence sensor has the problems of insufficient luminous intensity and stability and low sensitivity.
Disclosure of Invention
The invention aims to solve the technical problem of providing an electrochemiluminescence sensor for detecting bisphenol A, which has good selectivity, stability and high sensitivity in the detection of BPA in an environmental water sample, and a preparation method and application thereof.
The technical scheme adopted by the invention for solving the technical problems is as follows: an electrochemiluminescence sensor for detecting bisphenol A, which comprises a working electrode, wherein the working electrode comprises a substrate, a compound layer and a modification layer, and is characterized in that: the substrate is made of a glassy carbon conductive material, and the composite layer is magnetic Fe uniformly dispersed on the surface of the substrate3O4The modification layer is composed of perfluorosulfonic acid modified on the surface of the composite layer, and an alkaline luminol solution is used as an electrolyte to construct the electrochemiluminescence sensor for detecting bisphenol A.
The preparation method of the electrochemiluminescence sensor for detecting bisphenol A comprises the following steps:
（1）Fe3O4nanocrystals (Fe)3O4Preparation of-NCs)
A. Preparing an iron oleate precursor solution: 2.53g of FeCl were weighed3·6H2Dissolving O in 25mL of secondary water; 8.86mL of oleic acid was dissolved in 32mL of ethanol; mixing the two solutions, adding the mixture into a three-neck flask, stirring for 4 hours at 70 ℃, separating the solution into two layers, washing the upper layer containing the iron oleate compound in a separating funnel for 3 times by using deionized water, and then removing n-hexane under a vacuum condition to obtain a waxy solid, namely the iron oleate compound;
B. 1mL of iron oleate complex, 3mL of n-Trioctylamine (TOA) was dissolved in 8mL of Octadecene (ODE)Putting the mixed solution into a three-neck flask, vacuumizing for 1 hour at 100 ℃, then raising the reaction temperature to 320 ℃ at the rate of 10 ℃ per minute under the protection of nitrogen, and reacting for 0.5 hour to obtain Fe3O4-a raw NCs solution;
C. in Fe3O4Adding 20mL of chloroform and 20mL of ethanol to the NCs original solution, centrifuging at 3000 g for 10 min, removing supernatant, and re-dispersing the precipitate into chloroform to obtain Fe3O4-a solution of NCs;
(2) preparation of electrochemiluminescence sensor
A. Polishing the glassy carbon electrode by using alumina slurry with the particle size of 0.05-0.07 mu m, washing dirt on the surface of the electrode by using ethanol and ultrapure water respectively, and airing for later use; wherein the alumina slurry is prepared by mixing alumina powder and ultrapure water according to the mass ratio of 1:1, mixing to obtain the product;
B. sucking 5.0 mul of uniformly dispersed Fe with the concentration of 4-12 mg/mL3O4Dripping NCs solution on the surface of the glassy carbon electrode, naturally airing at room temperature, dripping 5-10 mu L of 1% perfluorosulfonic acid ethanol solution with volume concentration on the surface of the glassy carbon electrode, naturally airing, rinsing the surface of the electrode without adsorbing reagent materials by using 0.1M PBS buffer solution, and airing to obtain a working electrode Nafion/Fe3O4NCs/GCE, an electrochemiluminescence sensor for detecting bisphenol A, and is stored in a refrigerator at 4 ℃ for later use.
The alumina slurry in the step (2) is prepared by mixing alumina powder and ultrapure water according to the mass ratio of 1:1, mixing to obtain the product.
Fe described in step (2)3O4The concentration of NCs solution was 8 mg/mL.
The method for detecting the concentration of the bisphenol A by using the electrochemiluminescence sensor for detecting the bisphenol A comprises the following specific steps: the electrochemiluminescence sensor is taken as a working electrode, a platinum wire electrode is taken as an auxiliary electrode, Ag/AgCl is taken as a reference electrode and is inserted into a corresponding hole groove of an electrolytic cell, and the electrolytic cell is arranged right above a photomultiplier in a dark box of the electrochemiluminescence detector; the experiment adopts cyclic voltammetry, the negative high voltage of a photomultiplier is set to be 500V, and the test is carried outThe voltage range is 0 to +1.8V, and the scanning speed is 100 mV/s; the test is carried out at room temperature, before the test, 2mL of ultrapure water is taken into an electrolytic cell, the pH value of an electrochemiluminescence system is adjusted to be 11.0, 160 microliter of ultrapure water with the concentration of 5 multiplied by 10 is added into the electrochemiluminescence system-5And adding the solution of bisphenol A to be detected into the electrolytic cell, carrying out electrochemiluminescence test on the system, and determining the concentration of bisphenol A in the sample to be detected according to the quantitative relation between the electrochemiluminescence intensity and the concentration of bisphenol A.
Compared with the prior art, the invention has the advantages that: the invention relates to an electrochemiluminescence sensor for detecting bisphenol A, a preparation method and application thereof, wherein the sensor is based on magnetic ferroferric oxide nanocrystals/perfluorinated sulfonic acid resin film (Fe)3O4-NCs/nafion) composite material, with magnetic Fe3O4Nanocrystals (Fe)3O4-NCs) as a catalyst, perfluorosulfonic acid (nafion) as a film forming agent, and a glassy carbon electrode (GCE, 3 mm) as a working electrode, and nafion/Fe is prepared3O4-NCs/GCE modified electrode, alkaline luminol solution as electrolyte, due to Fe3O4The nanocrystal has excellent monodispersity and superparamagnetism, can obviously enhance anode electrochemiluminescence of luminol, and obtains the strongest chemiluminescence intensity value at +1.6V, and has the following advantages:
(1) the invention utilizes the dropping coating method to prepare nafion/Fe3O4the-NCs/GCE composite material modified glassy carbon electrode is simple to manufacture, low in material price, green, environment-friendly and good in stability.
(2) The electrochemiluminescence sensor prepared by the invention is used for detecting bisphenol A, is simple to operate, has a wide linear range and a low detection limit, and can realize simple, rapid and high-sensitivity detection of bisphenol A. When the concentration of BPA is 0.01-50.0 mg/L, the electrochemiluminescence signal inhibition response and the concentration of BPA have good linear correlation (r =0.9972), and the detection limit is 0.66 mu g/L.
(3) In the actual water sample detection, the actual sample standard adding recovery rate is 96.0-105.0%, and the relative standard deviation is less than 4.8%. The result shows that the electrochemiluminescence sensor is simple in preparation process, stable in detection result and good in accuracy and precision.
In conclusion, the electrochemiluminescence sensor for detecting bisphenol A, the preparation method and the application thereof are disclosed, the electrochemiluminescence sensor is used for detecting BPA based on the ferroferric oxide nanocrystal sensitized luminol electrochemiluminescence sensor, the preparation and detection method is simple, the sensitivity is high, the bisphenol A detection process is not influenced by structural analogues and the like, the anti-interference performance is good, and the electrochemiluminescence sensor has the advantages of good selectivity, stability, high sensitivity and the like in the detection of BPA in an environmental water sample.
Drawings
FIG. 1 is a schematic diagram of an electrochemiluminescence sensor constructed according to the present invention for detecting bisphenol A;
FIG. 2 is Fe3O4-Transmission Electron Microscopy (TEM) of NCs;
FIG. 3 is Fe3O4-NCs fluorescence spectrum;
FIG. 4 is Fe3O4The hysteresis curves of NCs, the inset is the external magnetic field vs. Fe3O4-the effect of NCs solution;
FIG. 5 is a graph of the effect of different nanocrystals on an electrochemiluminescent system;
fig. 6 is an electrochemical impedance spectrum of the modified electrode: perfluorosulfonic acid/Fe3O4-NCs modified electrode (a), perfluorosulfonic acid modified electrode (b), Fe3O4-NCs modified electrode (c) and bare electrode (d);
FIG. 7 is an electrochemical impedance spectrum of a modified electrode; perfluorinated sulfonic acid/cadmium antimonide nanocrystal modified electrode (a), perfluorinated sulfonic acid/Fe3O4-NCs modified electrode (b), perfluorosulfonic acid/zinc sulfide nanocrystal modified electrode (c), perfluorosulfonic acid/zinc selenide nanocrystal modified electrode (d) and bare electrode (e);
FIG. 8 is a graph showing the effect of luminol addition on electrochemiluminescence intensity;
FIG. 9 is Fe3O4Concentration of NCs versus electrochemistryThe effect of the luminous intensity;
FIG. 10 is a graph showing the effect of pH on electrochemiluminescence intensity;
FIG. 11 is a representation of electrochemical stability of an electrochemiluminescence sensor in a detection system;
FIG. 12 shows the inhibition of different BPA concentrations on the electrochemiluminescence sensor, when the BPA is added in an amount of 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0, 5.0mg/L, the electrochemiluminescence intensity of the detection system continuously decreases;
FIG. 13 is a graph of the linearity of different BPA concentrations with the luminescence intensity of an electrochemiluminescence sensor;
FIG. 14 shows CYP, DES, E2Graph comparing the selective inhibition of the electrochemiluminescence sensor by four inhibitors such as INN and BPA.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
Detailed description of the preferred embodiment
An electrochemiluminescence sensor for detecting bisphenol A comprises a working electrode, wherein the working electrode comprises a substrate, a compound layer and a modification layer, the substrate is made of a glassy carbon conductive material, and the compound layer is magnetic Fe uniformly dispersed on the surface of the substrate3O4The preparation method of the nano-crystal comprises the following steps of:
（1）Fe3O4nanocrystals (Fe)3O4Preparation of-NCs)
A. Preparing an iron oleate precursor solution: 2.53g of FeCl were weighed3·6H2Dissolving O in 25mL of secondary water; 8.86mL of oleic acid was dissolved in 32mL of ethanol; mixing the above two solutions, adding into a three-neck flask, stirring at 70 deg.C for 4 hr to separate the solution into two layers, washing the upper layer containing iron oleate complex with deionized water in a separating funnel for 3 times, and removing n-hexane under vacuum condition to obtain waxy substanceThe solid is an iron oleate compound;
B. dissolving 1mL of iron oleate complex and 3mL of n-Trioctylamine (TOA) in 8mL of Octadecene (ODE), placing the mixed solution in a three-neck flask, vacuumizing at 100 ℃ for 1 hour, raising the reaction temperature to 320 ℃ at the rate of 10 ℃ per minute under the protection of nitrogen, and reacting for 0.5 hour to obtain Fe3O4-a raw NCs solution;
C. in Fe3O4Adding 20mL of chloroform and 20mL of ethanol to the NCs original solution, centrifuging at 3000 g for 10 min, removing supernatant, and re-dispersing the precipitate into chloroform to obtain Fe3O4-a solution of NCs;
firstly, prepared Fe is subjected to Lorentz transmission electron microscope3O4-microscopic characterisation of the morphological morphology of the NCs. As shown in FIG. 2 Fe3O4Transmission Electron Microscopy (TEM) of NCs shows the synthesized tetra-Fe3O4The NCs have good dispersion and uniform size, the size is about 22.0nm, and the good dispersion is beneficial to the stability of electrochemical properties, so that the constructed electrochemiluminescence sensor has better stability and repeatability. Meanwhile, as can be seen from FIG. 3, Fe3O4Fluorescence excitation wavelength and emission wavelength of NCs are 300 nm and 590nm, respectively, from which it can be concluded that Fe was produced3O4NCs are nano particles with certain fluorescence characteristics, and have certain sensitization effect on a luminol electrochemiluminescence reaction system under the existence condition. As can be further seen from FIG. 4, Fe3O4The superparamagnetism of the NCs determines that the NCs present a specific direction without aggregation and agglomeration, which is beneficial to uniformly dispersing the NCs on the surface of an electrode, so that the prepared electrochemiluminescence sensor has stable properties;
(2) preparation of electrochemiluminescence sensor
A. Polishing the glassy carbon electrode by using alumina slurry with the particle size of 0.05-0.07 mu m, washing dirt on the surface of the electrode by using ethanol and ultrapure water respectively, and airing for later use; wherein the alumina slurry is prepared by mixing alumina powder and ultrapure water according to the mass ratio of 1:1, mixing to obtain the product;
B. sucking 5.0 mul of uniformly dispersed Fe with the concentration of 4-12 mg/mL3O4Dropping NCs solution on the surface of the glassy carbon electrode, naturally airing at room temperature, then dropping 5-10 mu L of 1% perfluorosulfonic acid ethanol solution (the volume ratio of perfluorosulfonic acid to ethanol is 1: 100) with volume concentration on the surface of the glassy carbon electrode, naturally airing, then rinsing the surface of the electrode without adsorbing reagent materials by using 0.1M PBS buffer solution, and airing to obtain a working electrode Nafion/Fe3O4NCs/GCE, an electrochemiluminescence sensor for detecting bisphenol A, and is stored in a refrigerator at 4 ℃ for later use. Nafion/GCE, Nafion/ZnS/GCE, Nafion/ZnSe/GCE, Nafion/CdS/GCE and Nafion/CdTe/GCE were prepared using the same method for comparative experimental analysis.
Electrochemical characterization of the electrochemiluminescence sensor: electrochemical impedance testing was performed using CHI660E to electrochemically characterize the modified electrode surface. Research shows that the metal nano crystal has better enhancement performance on luminol cathode electrochemiluminescence or anode electrochemiluminescence; therefore, the experiment firstly adopts cyclic voltammetry and corresponding electrochemiluminescence analysis method for different metal nanocrystals and Fe3O4-comparative analysis, characterization between NCs modified electrodes. When the scanning potential range of the cyclic voltammetry is-1.8 to +1.8V, luminol cathode luminescence is not found, and luminol weak anode luminescence is found. As shown in fig. 5, the anode electrochemiluminescence value of the bare glassy carbon electrode reaches the maximum when the potential is 1.58V; fe when the potential is 1.4V3O4The anode electrogenerated chemiluminescence values of the nanocrystal, ZnS nanocrystal and ZnSe nanocrystal modified electrodes reach the maximum. The comparison shows that the CdS nanocrystal and the CdTe nanocrystal hardly have sensitization effect on luminol cathodoluminescence. As can be seen from FIG. 5, at a potential of 1.4V, Fe3O4The electrochemiluminescence intensity generated by the nanocrystal modified electrode is the maximum, and the signal value of the electrochemiluminescence intensity is 4 times that of the electrochemiluminescence signal value generated by the ZnS nanocrystal modified electrode. This is due to Fe3O4The good electrochemical catalysis of the nano crystal produces sensitization effect on luminol electrochemiluminescenceThe application is as follows.
The working electrode modification process and the electrochemiluminescence mechanism can be explained by electrochemical impedance tests. As shown in fig. 6, the nyst curve shows a semicircular arc line for all the modified electrodes, and the abscissa value corresponding to the vertical tangent of the semicircular arc line is the resistance value of the modified electrode. As shown in FIG. 6, bare electrode, perfluorosulfonic acid modified electrode, Fe3O4-NCs modified electrode, perfluorosulfonic acid/Fe3O4The resistance values of the NCs modified electrode are 150.0 omega, 130.0 omega, 1400 omega and 123.0 omega respectively. The results show that perfluorosulfonic acid and Fe3O4NCs were successfully modified to the surface of the working electrode and perfluorosulfonic acid/Fe3O4The NCs modified electrode has better conductivity. Respectively reacting perfluorosulfonic acid/Fe3O4-NCs, perfluorosulfonic acid and Fe3O4Modifying NCs on the surface of the bare electrode, wherein the resistance value of the modified electrode is lower than that of the bare electrode. The results show that perfluorosulfonic acid and Fe3O4NCs are each effective in promoting the conductivity of the working electrode, Fe3O4NCs are capable of promoting the electron transfer rate of the system. It can also be seen from FIG. 6 that perfluorosulfonic acid/Fe3O4Resistance ratio Fe of NCs modified electrode3O4The resistance value of-NCs (ferroferric oxide nanocrystal) modified electrode is lower, which indicates that perfluorosulfonic acid is combined with Fe3O4NCs modified electrode vs. Fe alone3O4The NCs modified electrode has higher charge transfer efficiency, which also shows that the use of the perfluorosulfonic acid not only can play the role of a film-forming agent, but also can promote Fe3O4NCs modify the electron transport of the electrode. In addition, as can be seen from fig. 7, the resistance values of both the perfluorosulfonic acid/zinc selenide nanocrystal-modified electrode and the perfluorosulfonic acid/zinc sulfide nanocrystal-modified electrode were higher than those of perfluorosulfonic acid/Fe3O4The resistance value of the NCs modified electrode is large. This indicates that the perfluorosulfonic acid/ferroferric oxide nanocrystal modified electrode has higher conductivity, which is consistent with the results in fig. 6. In conclusion, the sensitization effect of the perfluorinated sulfonic acid/ferroferric oxide nanocrystal modified electrode on luminol electrochemiluminescence is benefited by the sensitization effectGood conductivity and electrochemical catalytic activity. Thus, perfluorosulfonic acid/Fe was chosen3O4NCs modified electrodes the next optimization experiment was performed.
Detailed description of the invention
Optimization of electrochemiluminescence systems
1. Effect of luminol addition on electrochemiluminescence intensity
As an electrochemiluminescence precursor substance, the influence of the luminol concentration on the electrochemiluminescence intensity of a detection system is very important. If the concentration of the luminol is too low, the generation of excited state luminol can be influenced, and the electrochemiluminescence efficiency is influenced; too high luminol concentration may affect the stability and sensitivity of the electrochemiluminescence sensor and may not contribute to the amplification of the luminol electrochemiluminescence signal value. As can be seen from the effect of luminol concentration on the intensity of electrochemiluminescence in FIG. 8, when the amount of luminol solution (5.0X 10-5M in 0.01M NaOH) added was increased from 0.0 to 160.0. mu.L, the electrochemiluminescence signal of the system increased rapidly and reached a maximum at 160.0. mu.L (1560 a.u.); when the luminol concentration continues to increase, the electrochemiluminescence signal value of the detection system continuously decreases, and the noise value of the detection instrument rises. Therefore, 160.0. mu.L of luminol solution with a concentration of 5.0X 10-5M was chosen.
2、Fe3O4Influence of the concentration of NCs on the intensity of electrochemiluminescence
As luminol electrochemiluminescence sensitizer, Fe3O4The concentration of NCs has a significant influence on the sensitivity of the detection system. Fe3O4Too low concentration of NCs can cause the conductivity of the modified electrode to be reduced, and is not beneficial to the generation of excited state luminol, thereby influencing the amplification of the optical signal value of the detection system; fe3O4When the concentration of NCs is too high, the thickness of a modification layer on the surface of the modified electrode is increased, the resistance value is increased, and the modified electrode is easy to fall off, so that the stability of a detection system is influenced. Therefore, we are dealing with Fe3O4The concentration of NCs is optimized. As a result, as shown in FIG. 9, when Fe3O4NCs concentration from 1When the concentration of 0 mg/mL is increased to 8.0 mg/mL, the electrochemiluminescence intensity of the detection system is continuously increased and reaches the maximum value when the concentration of 8.0 mg/mL is increased; when Fe3O4As the concentration of-NCs continues to increase, the electrochemiluminescence intensity of the detection system decreases rapidly. Thus, Fe3O4The concentration of-NCs was chosen to be 8.0 mg/mL.
3. Effect of pH on the intensity of electrochemiluminescence
Because luminol electrochemiluminescence is a pH-dependent reaction, when the pH value is too low, the luminol is not beneficial to hydrolysis and ionization, so that the electrochemiluminescence reaction is influenced; when the pH value is too high, the BPA structure is damaged, the background luminous value of the detection system is increased, and the sensitivity of the sensor is reduced, so that the experiment discusses the influence of the pH value of 7.0-12.0 on the electrochemiluminescence intensity of the detection system. As can be seen from FIG. 10, when the pH of the detection system is 7.0-11.0, the electrochemiluminescence intensity increases with the increase of the pH value of the system, and the maximum value is obtained at 11.0; when the pH value of the detection system continues to increase, the electrochemiluminescence intensity is rapidly reduced, and the background luminescence value of the detection system is rapidly increased. Therefore, the pH was chosen to be 11.0.
Detailed description of the preferred embodiment
The method for detecting the concentration of the bisphenol A by using the electrochemiluminescence sensor for detecting the bisphenol A, which is prepared under the optimized conditions of the first specific embodiment and the second specific embodiment, comprises the following specific steps: the electrochemiluminescence sensor is used as a working electrode, a platinum wire electrode is used as an auxiliary electrode (a counter electrode), Ag/AgCl (KCl saturated solution saturated by AgCl) is used as a reference electrode and is inserted into a corresponding hole groove of an electrolytic cell, and the electrolytic cell is arranged right above a photomultiplier in a dark box of the electrochemiluminescence detector. The experiment adopts Cyclic Voltammetry (CV), the negative high voltage of a photomultiplier is set to be 500V, the test voltage range is 0 to +1.8V (vs. Ag/AgCl), and the scanning rate is 100 mV/s. The test was carried out at room temperature, before the test, 2mL of ultrapure water was placed in an electrolytic cell, the pH of the electrochemiluminescence system was adjusted to 11.0, 160. mu.l of 5X 10 was added to the electrochemiluminescence system- 5M in luminol. Adding bisphenol A to the electrolytic cell to make the concentration of bisphenol A0, 0.02, 0.05, 0.1, 0.4, 0.5, 1.0, 2.0, 5.0mg/L, and an electrochemiluminescence test was performed on the above system, and the electrochemiluminescence intensity (ECL intensity) was used as a quantitative analysis object.
The stability and reproducibility of the electrochemiluminescence sensor are of great significance to its practical application. Under the optimal optimization condition, the electrochemiluminescence sensor is scanned for 15 times continuously by adopting cyclic voltammetry.
As shown in fig. 11, the electrochemiluminescence signal intensity values of 15 scans were very stable (RSD < 0.42%) at the potential of 0.0-1.8V, indicating that the prepared electrochemiluminescence sensor was good in stability. In addition, five electrodes were prepared in the same manner to test the reproducibility of the detection method, and the results showed that the electrochemiluminescence signal values using the five electrodes were relatively stable in the presence of BPA (RSD = 3.6%); after three weeks, the response value of the luminescence signal of the electrochemiluminescence sensor can still reach 96.2% of the original value. The result shows that the established electrochemistry detection method has better stability and repeatability and can be applied to the actual detection of BPA.
As shown in FIG. 12, the electrochemiluminescence intensity of the detection system decreased when the amount of BPA added was 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 mg/L.
As shown in FIG. 13, Log (C) is a logarithmic value of BPA concentration valueBPA) Linear fitting analysis is performed by taking the luminous intensity value as a vertical coordinate. It can be seen that when the concentration of BPA is in the range of 0.02-5.0 mg/L, a good linear relationship is presented between the logarithm of the concentration value of BPA and the luminous intensity value of the detection system, and the linear correlation coefficient is 0.9972. And further diluting the concentration of BPA within a linear range of 0.02-5.0 mg/L, and taking the signal-to-noise ratio of 3 (S/N = 3) as a standard, wherein the detection limit of the method can reach 0.66 mu g/L.
Detailed description of the invention
Selective testing of electrochemiluminescence sensors on bisphenol A structural analogs
The electrochemiluminescence sensor is used as a working electrode, a platinum wire electrode is used as an auxiliary electrode, and Ag/AgCl is used as a reference electrodeInserting into the corresponding hole groove of the electrolytic cell, and placing the electrolytic cell right above the photomultiplier in the dark box of the electrochemiluminescence detector. The experiment adopts Cyclic Voltammetry (CV), the negative high voltage of a photomultiplier is set to be 500V, the test voltage range is 0 to +1.8V (vs. Ag/AgCl), and the scanning rate is 100 mV/s. The test is carried out at room temperature, before the test, 2mL of ultrapure water is taken into an electrolytic cell, the pH value of an electrochemiluminescence system is adjusted to be 11.0, 160 microliter of ultrapure water with the concentration of 5 multiplied by 10 is added into the electrochemiluminescence system-5M in luminol. Bisphenol A (BPA), estragole (INN), beta-estradiol (E2), Diethylstilbestrol (DES) and Cypermethrin (CYP) are added into an electrolytic cell to ensure that the concentrations of the components are all 2.0 mg/L, and the system is subjected to an electrochemiluminescence test. With (I)0-I)/I0Is defined as the inhibition rate, wherein, I0Indicating the electrochemiluminescence intensity value of the detection system in the absence of the inhibitor; and I represents the electrochemiluminescence intensity value of the detection system when the inhibitor exists. CYP, DES and E are experimentally and comparatively tested under the optimal detection condition2And INN and BPA, and selective inhibition of the electrochemiluminescence sensor by the BPA.
As shown in fig. 14, the inhibition ratio of BPA to the luminescence intensity of the electrochemiluminescence sensor was 97.4%, and the inhibition effect was the most significant; the inhibition rate of INN to the luminous intensity of the electrochemiluminescence sensor is 1.9%, and the inhibition effect is not obvious; CYP, DES and E2The luminescence intensity of the electrochemiluminescence sensor is not inhibited, but gain effect is generated. The result shows that by controlling the range of oxidation potential, the electrochemiluminescence sensor has better selective inhibition to BPA, and can still exert better application effect under the condition of the existence of interferents.
Detailed description of the preferred embodiment
In order to measure the detection application effect of the established electrochemiluminescence sensor in actual samples, a matrix standard adding experiment is carried out.
Tap water was taken from Ningbo university and river water was taken from Ningbo Yongjiang. The collected water sample is firstly filtered by a 0.45 mu M filter membrane to remove impurities, and then the pH value is adjusted to 11.0 by using a NaOH solution with the concentration of 1.0M for later use. The concentrations adopted in the matrix labeling experiment are 0.01, 0.1 and 0.2mg/L respectively.
TABLE 1 actual sample in-label recovery experiment
For both the tap water and the river water practical samples, a spiking recovery experiment (n = 3) was performed to verify the performance of the electrochemiluminescence sensor in practical applications. The accuracy and precision of the method can be assessed by the recovery of the spiked and the relative standard deviation between parallel samples. As shown in Table 1, in the river water sample, when the adding concentration is 0.01, 0.1 and 0.2mg/L, the recovery rate is 96.0-101.2%, and the relative standard deviation between parallels is lower than 4.6%; in tap water, when the addition concentration is 0.1, 1.0 and 5.0 mu g/L, the recovery rate is 99.0-105.0 percent, and the relative standard deviation between parallel samples is lower than 4.6 percent. The result shows that the prepared electrochemiluminescence sensor has better accuracy and precision for detecting BPA in river water and tap water.
In summary, the present invention uses magnetic Fe3O4Nanocrystals (Fe)3O4NCs) as a catalyst, perfluorosulfonic acid (Nafion) as a film forming agent, and a glass carbon electrode (GCE, 3.0 mm) as a working electrode, and Nafion/Fe was prepared3O4-NCs/GCE modified electrodes; a novel electrochemiluminescence sensor is constructed by taking an alkaline luminol solution as an electrolyte and is successfully applied to specific detection of BPA in an environmental water sample. The result shows that compared with zinc sulfide, zinc selenide, cadmium sulfide and cadmium antimonide nano particles, the synthesized ferroferric oxide nano crystal with good dispersion and excellent superparamagnetism can obviously enhance the anode electrochemiluminescence of the alkaline luminol system under the potential of + 1.6V. By controlling the potential, under the condition of an optimal detection system, the electrochemiluminescence sensor has better selective inhibition on BPA, the linear detection range is 0.01-50.0 mg/L (r =0.9972), and the detection limit is 0.66 mu g/L. The recovery rate of the actual sample by adding the standard is 96.0-105.0%,the relative standard deviation is less than 4.8%. The result shows that the electrochemiluminescence sensor is simple in preparation process, stable in detection result, good in accuracy and precision, capable of meeting the detection requirement of BPA in a water sample, and provides a new idea for the application of the electrochemiluminescence sensor technology in the field of monitoring of the quality of environmental water and drinking water.
Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Those skilled in the art should also realize that such changes, modifications, additions and substitutions are within the true spirit of the invention.
Claims (4)
1. An electrochemiluminescence sensor for detecting bisphenol A, which comprises a working electrode, wherein the working electrode comprises a substrate, a compound layer and a modification layer, and is characterized in that: the substrate is made of a glassy carbon conductive material, and the composite layer is magnetic Fe uniformly dispersed on the surface of the substrate3O4The modification layer is composed of perfluorosulfonic acid modified on the surface of the composite layer, and an alkaline luminol solution is used as an electrolyte to construct the electrochemiluminescence sensor for detecting bisphenol A.
2. A method for preparing an electrochemiluminescence sensor for detecting bisphenol a according to claim 1, comprising the steps of:
（1）Fe3O4preparation of nanocrystals
A. Preparing an iron oleate precursor solution: 2.53g of FeCl were weighed3·6H2Dissolving O in 25mL of secondary water; 8.86mL of oleic acid was dissolved in 32mL of ethanol; mixing the two solutions, adding the mixture into a three-neck flask, stirring the mixture for 4 hours at 70 ℃, separating the solution into two layers, washing the upper layer containing the iron oleate compound in a separating funnel for 3 times by using deionized water, and then removing n-hexane under a vacuum condition to obtain waxy solid, namely the iron oleate compound;
B. dissolving 1mL of iron oleate complex and 3mL of n-trioctylamine in 8mL of octadecene, and mixingPutting the solution into a three-neck flask, vacuumizing for 1 hour at 100 ℃, then increasing the reaction temperature to 320 ℃ at the rate of 10 ℃ per minute under the protection of nitrogen, and reacting for 0.5 hour to obtain Fe3O4-a raw NCs solution;
C. in Fe3O4Adding 20mL of chloroform and 20mL of ethanol to the NCs original solution, centrifuging at 3000 g for 10 min, removing supernatant, and re-dispersing the precipitate into chloroform to obtain Fe3O4-a solution of NCs;
(2) preparation of electrochemiluminescence sensor
A. Polishing the glassy carbon electrode by using alumina slurry with the particle size of 0.05-0.07 mu m, washing dirt on the surface of the electrode by using ethanol and ultrapure water respectively, and airing for later use; wherein the alumina slurry is prepared by mixing alumina powder and ultrapure water according to the mass ratio of 1:1, mixing to obtain the product;
B. sucking 5.0 mul of uniformly dispersed Fe with the concentration of 4-12 mg/mL3O4Dripping NCs solution on the surface of the glassy carbon electrode, naturally airing at room temperature, dripping 5-10 mu L of 1% perfluorosulfonic acid ethanol solution with volume concentration on the surface of the glassy carbon electrode, naturally airing, rinsing the surface of the electrode without adsorbing reagent materials by using 0.1M PBS buffer solution, and airing to obtain a working electrode Nafion/Fe3O4NCs/GCE, an electrochemiluminescence sensor for detecting bisphenol A, and is stored in a refrigerator at 4 ℃ for later use.
3. The method of claim 2, wherein the electrochemiluminescence sensor is a sensor for detecting bisphenol a, the electrochemiluminescence sensor comprising: fe described in step (2)3O4The concentration of NCs solution was 8 mg/mL.
4. A method for detecting bisphenol A using the electrochemiluminescence sensor for detecting bisphenol A according to claim 1, comprising the steps of: the electrogenerated chemiluminescence sensor is used as a working electrode, a platinum wire electrode is used as an auxiliary electrode, an Ag/AgCl electrode is used as a reference electrode and is inserted into a corresponding hole groove of an electrolytic cell, and the electrolytic cell is placed in a dark box of an electrogenerated chemiluminescence detector for photoelectric multiplicationThe upper part of the pipe is arranged right above the pipe; the experiment adopts cyclic voltammetry, the negative high voltage of a photomultiplier is set to be 500V, the test voltage range is 0 to +1.8V, and the scanning rate is 100 mV/s; the test is carried out at room temperature, before the test, 2mL of ultrapure water is taken into an electrolytic cell, an electrochemiluminescence system is adjusted, 160 microliters of 5 multiplied by 10 concentration is added into the electrochemiluminescence system-5And adding the solution of bisphenol A to be detected into the electrolytic cell, carrying out electrochemiluminescence test on the system, and determining the concentration of bisphenol A in the sample to be detected according to the quantitative relation between the electrochemiluminescence intensity and the concentration of bisphenol A.
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