CN117805211A - Paper-based flexible electrode for detecting hydroquinone in environmental water sample and preparation method thereof - Google Patents
Paper-based flexible electrode for detecting hydroquinone in environmental water sample and preparation method thereof Download PDFInfo
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- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 title claims abstract description 127
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Landscapes
- Inks, Pencil-Leads, Or Crayons (AREA)
Abstract
The invention discloses a paper-based flexible electrode for detecting hydroquinone in an environmental water sample and a preparation method thereof, and relates to the technical field of environmental pollution detection. S1: drawing a three-electrode model; s2: printing a paper-based electrode; s3: preparing and packaging a carbon-based electrode; s4: and (5) electrochemical testing. The A5 photo paper is used as a printing base material, and the carbon-based ink is successfully printed on the surface of the paper by using the ink-jet printing process of the novel microelectronic printer without further modification. Wherein, the carbon-based ink is used as a Working Electrode (WE) and an auxiliary electrode (CE), and Ag/AgCl is coated as a Reference Electrode (RE) to form a complete three-electrode system. The carbon-based electrode was characterized and tested using scanning electron microscopy, micro-laser raman spectroscopy, cyclic Voltammetry (CV), differential Pulse Voltammetry (DPV), and the like. The sensor has strong electrochemical performance, good detection performance and repeatability on HQ, and wide application prospect in electrochemical monitoring.
Description
Technical Field
The invention relates to the technical field of environmental pollution detection, in particular to a paper-based flexible electrode for detecting hydroquinone in an environmental water sample and a preparation method thereof.
Background
Hydroquinone (HQ) is a disubstituted phenolic compound widely used in the industrial fields of dyes, pharmaceuticals, textiles, cosmetics, oil refining, etc. HQ is highly toxic to humans and the environment, can cause syncope, somnolence, skin diseases, headache, vomiting, even affect the nervous system, and is hardly degradable in the natural environment system. Therefore, developing a rapid, economical, highly sensitive analytical method to determine HQ is an important task for researchers. In previous studies, a number of analytical techniques have been used to detect HQ in environmental samples, such as High Performance Liquid Chromatography (HPLC), spectrophotometry, gas chromatography-mass spectrometry (GC-MS), fluorescence, and the like. Among them, GC-MS and HPLC techniques are expensive, time consuming, and require highly complex instrumentation and organic solvents, while fluorescence spectra are difficult to reproduce. In environmental detection, electrochemical methods often use the principle of measuring the redox behavior of an analyte, and have the advantages of low cost, rapid response, easy operation, high selectivity, sensitivity and the like, thus making the electrochemical methods an ideal technology for detecting HQ. Because the three-electrode system is frequently used for measuring various environmental pollutants, the development of a quick, sensitive, simple and portable carbon-based three-electrode system has very important significance for environmental pollutant detection.
Compared with the traditional glassy carbon electrode, the method can avoid the defects that the electrode is subjected to repeated polishing procedures and is easy to contain impurities and the like, and realizes portable rapid detection. The ink-jet printing paper-based electrode is an electrode constructed by a conductive material printed on the surface of paper by an ink-jet technology, has simple preparation, low cost, good flexibility and portability, and can be reused by a simple method. In the process of preparing an ink-jet printing paper-based electrode, the electrode structure is usually constructed by printing particles on the surface of the paper by an ink-jet printing technique. Finally, the paper-based electrode which can be used for electrochemical analysis is prepared through procedures such as drying and solidification. In the electrochemical analysis experiments, paper-based electrodes were used as working or counter electrodes. The electrochemical signal of the analyte compound is obtained by applying a potential or current to modulate the occurrence of the electrode surface reaction. Finally, information such as the structure, the property, the concentration and the like of the target compound can be obtained through signal processing.
The full-printed electrochemical device is increasingly focused by researchers in the fields of clinic, food, environmental monitoring and the like due to the characteristics of low cost, good reproducibility, strong universality and the like, and the flexible sensor has become an important tool for easy use and miniaturization. In order to reduce the emission of electronic waste, researchers have been looking for low cost disposable electrode materials. The paper is used as a material with multifunctional potential, and has the characteristics of low cost, recoverability, degradability, easy modification and the like, thereby providing a prerequisite for developing a novel low-cost detection type sensor. Paper-based electroanalytical devices combine the advantageous properties of electrochemical sensing (e.g., high sensitivity, good selectivity, portability, and low power consumption) with paper-based materials to convert the chemical quantity of target analytes into electrical signals, with great potential and applicability in various assays. The novel electrochemical sensor based on paper is researched and developed, and is expected to realize low-cost, quick response and high-sensitivity detection of various environmental pollutants.
Disclosure of Invention
The invention aims to provide a paper-based flexible electrode for detecting hydroquinone in an environmental water sample and a preparation method thereof, wherein A5 photo paper is used as a printing base material, and carbon-based ink is successfully printed on the surface of paper by using an inkjet printing procedure of a novel microelectronic printer without further modification. Wherein, the carbon-based ink is used as a Working Electrode (WE) and an auxiliary electrode (CE), and Ag/AgCl is coated as a Reference Electrode (RE) to form a complete three-electrode system.
The technical aim of the invention is realized by the following technical scheme: a paper-based flexible electrode for detecting hydroquinone in an environmental water sample and a preparation method thereof comprise the following steps: s1: drawing a three-electrode model; s2: printing a paper-based electrode; s3: preparing and packaging a carbon-based electrode; s4: and (5) electrochemical testing.
The invention is further provided with: in the step S1, firstly, drawing a basic frame at the lower part of an electrode in a three-electrode system, then, drawing the top of a working electrode, finishing frame drawing, drawing two concentric circles with proper sizes as arc parts of a counter electrode and a reference electrode by taking the circle center of the circle at the top of the working electrode as a reference, finally, selecting a deleting tool, wiping off redundant parts, filling a contour, checking whether all dimensional parameters meet requirements, and finishing drawing; the first electrode after drawing is used as the reference, the electrodes are copied in batches, so that the electrodes are orderly arranged on photographic paper, the patterns are ensured to be fully paved on the paper, and enough cutting gaps are reserved; and outputting the data, uploading the data to operation software of the microelectronic printer, checking whether each parameter is qualified again, and preparing for printing.
The invention is further provided with: the printing of the paper-based electrode in the step S2 is as follows:
(1) Turning on a power supply of the microelectronic printer; regulating the air pump pressure to 0.45Mpa, and opening a switch of the air pump to a first gear; opening software of the microelectronic printer, connecting the computer with the printer, and automatically performing zero setting and part resetting on the printer after the connection is completed;
(2) Opening the ink bag cover, and injecting a proper amount of printing test ink into the ink bag by using a circular needle; taking out the ink-jet printing head, lightly touching the silicon chip part of the printing head by using the dust-free paper which is wet by alcohol, and sucking excessive alcohol by using the clean dust-free paper; taking out the ink box, and assembling the ink jet head and the ink bag;
(3) Placing the assembled ink box in an ink box mounting position in a printer;
(4) Before printing starts, a clean cotton core is installed; selecting a waveform file corresponding to the printing ink and the number of printing holes required, clicking a cleaning button to start cleaning;
(5) Leading in three drawn electrodes, and adjusting proper size and typesetting;
(6) Putting photographic paper in the printer, and opening an adsorption button; clicking a print button to check three options of printing hole selection, ink selection and adsorption selection, checking without errors, and clicking a start print;
(7) Waiting for the process window to display 'completed', indicating that printing is finished; taking out the photographic paper and the ink box, and displaying printed three-electrode patterns on the photographic paper; disassembling and assembling the ink cartridge according to the reverse step of the 'mounting ink cartridge' operation; and (3) disconnecting the computer from the printer, and closing the printer, the air pump and the computer power supply.
The invention is further provided with: after printing of the carbon-based electrode is completed, cutting the printed electrode into a proper size; dipping a proper amount of Ag/AgCl ink by using a needle head of a 0.25 mu m filtering needle tube, and uniformly smearing the needle head on the end of a printed reference electrode; naturally drying the Ag/AgCl ink, and completing the solidification; at this time, a piece of adhesive tape with a fixed size is cut and stuck on the lead part of the three electrodes, and the whole electrode is prepared and packaged.
The invention is further provided with: when electrochemical test is carried out, the electrode plate is placed in an electrode clamp of the portable device and immersed in electrolyte, and the supporting electrolyte is Phosphate Buffer Solution (PBS) containing Na2HPO4, naH2PO4 and NaCl with different pH values; CV is carried out within a potential range of-0.2V-0.7V/-0.3V-0.6V, and the sweeping speed is 100mV/s; the potential window of DPV is-0.4V-0.6V, the pulse width is 0.2s, and the pulse amplitude is 0.01V.
The invention also provides a paper-based flexible electrode prepared by the preparation method based on the paper-based flexible electrode for detecting hydroquinone in the environmental water sample.
In summary, the invention has the following beneficial effects: the A5 photo paper is used as a printing base material, and the carbon-based ink is successfully printed on the surface of the paper by using the ink-jet printing process of the novel microelectronic printer without further modification. Wherein, the carbon-based ink is used as a Working Electrode (WE) and an auxiliary electrode (CE), and Ag/AgCl is coated as a Reference Electrode (RE) to form a complete three-electrode system. The carbon-based electrode was characterized and tested using scanning electron microscopy, micro-laser raman spectroscopy, cyclic Voltammetry (CV), differential Pulse Voltammetry (DPV), and the like. The sensor has strong electrochemical performance, good detection performance and repeatability on HQ, and wide application prospect in electrochemical monitoring.
Drawings
FIG. 1 is a schematic diagram of a bulk electrode on A5 photo paper as a whole and packaged single electrode after inkjet printing according to an embodiment of the present invention;
FIG. 2 is a flow chart of the ink jet printing technique for preparing flexible electrodes and electrochemically detecting hydroquinone according to the embodiment of the invention;
FIG. 3 is a graph showing the superposition of CVs in PBS solutions at different pH for HQ according to the example of the present invention;
FIG. 4 is a graph showing comparison of oxidation peak currents at different pH values for an embodiment of the present invention;
FIG. 5 is a graph of enrichment potential (A) and enrichment time (B) versus oxidation current for an embodiment of the invention;
FIG. 6 is a CV plot of different sweep rates of a sensor of an embodiment of the present invention in a PBS solution containing 10 μM HQ;
FIG. 7 is a graph of the log of sweep rate versus oxidation and reduction peak currents for an embodiment of the present invention;
FIG. 8 is a graph of DPV of a sensor of an embodiment of the invention at various HQ concentrations (a-h: 0.001,0.3,5, 10, 20, 50, 100, 300. Mu.M);
FIG. 9 is a graph of oxidation current versus HQ concentration for an embodiment of the present invention;
FIG. 10 shows the reproducibility (A) and repeatability (B) of HQ detection by the sensor according to the embodiment of the present invention;
FIG. 11 is an ultraviolet visible spectrum of HQ standard solutions of different concentrations according to an embodiment of the present invention;
FIG. 12 is a linear calibration curve of absorbance and HQ concentration for an embodiment of the invention;
FIG. 13 is an ultraviolet-visible spectrum of an example of the present invention for a labeled ambient water sample 1;
FIG. 14 is an ultraviolet-visible spectrum of an example of the present invention for labeling an environmental water sample 2;
FIG. 15 is a graph comparing the results of the sensor of the present invention with the results of an ultraviolet-visible spectrophotometer in the detection of environmental samples;
FIG. 16 is an SEM image of a carbon-based ink electrode after ink jet printing according to an embodiment of the present invention;
FIG. 17 is a Raman spectrum of a carbon-based ink after ink-jet printing according to an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to fig. 1-17.
Examples: the paper-based flexible electrode for detecting hydroquinone in an environmental water sample and the preparation method thereof are as shown in figures 1-17, and the preparation method of the paper-based flexible electrode for detecting hydroquinone is as follows:
1. drawing of three-electrode model
(1) A rectangular tool is selected to draw the lower base frame of the electrode and the rectangular protruding portion of the connecting lead in the three-electrode system.
(2) And selecting a round tool, drawing a circle with proper size as the top of the working electrode, and finishing the drawing of the working electrode.
(3) And (3) selecting a circular tool, drawing two concentric circles with proper sizes by taking the center of a circle at the top of the working electrode as a reference, and forming an arc, wherein the lower end of the arc is respectively connected with the counter electrode and the reference electrode.
(4) Selecting a deleting tool, wiping off the redundant part, and cutting off a small section on the circular arc to disconnect the counter electrode from the reference electrode.
(5) A filling tool is selected to fill the electrode profile, taking care of the small gaps between the contact portions of the different patterns.
(6) And checking whether each size parameter of the electrode meets the requirements of ink-jet printing and subsequent detection, and finishing drawing.
(7) The first electrode after drawing is used as the reference, and the electrodes are copied in batches in CAD so as to form 4*9 on the photographic paper in order, thereby ensuring that the patterns are fully laid on the paper and enough cutting gaps are reserved. And outputting the data, uploading the data to operation software of the microelectronic printer, and checking whether each parameter is qualified again. Printing is prepared.
2. Printing of paper-based electrodes
(1) Starting a computer, starting a machine, starting a pump and connecting the machine with the pump
Opening a computer: turning on a power supply of a host;
starting: when the power supply of the microelectronic printer is turned on, three sounds of 'dripping' appear, and the right lower corner indicator light turns green, the starting is finished.
And (3) starting a pump: adjusting the air pump pressure to 0.45 (Mpa), and opening a switch of the pump to a first gear (the first gear is an intermittent working mode);
and (5) online: and opening special software of the microelectronic printer, and connecting the computer with the printer at the upper right corner. After the connection is completed, the printer automatically performs zero setting work, including resetting of parts such as a turntable.
(2) Ink cartridge assembly
Use of ink bag: the ink bag cover is opened, and the printing test ink is injected into the ink bag by using a circular needle (the ink bag is prevented from being punctured by a sharp needle), and the ink is preferably injected into about two fifths of the volume of the ink bag.
Cleaning and assembly of spray heads
Cleaning: and taking out the ink-jet printing head, lightly touching the silicon chip part of the printing head by using the dust-free paper which is wet by alcohol, and wiping the silicon chip part by cutting marks without force so as to prevent the printing holes from being blocked, and sucking the excessive alcohol by using the clean dust-free paper.
And (3) assembling: taking out the ink box, assembling the ink jet head and the ink bag, opening the ink box cover, unscrewing the fixing screw at the side edge of the ink box, putting the ink jet head and the ink bag into the ink box, and screwing the screw.
(3) And (3) installing an ink box: the assembled ink box is placed in the ink box installation position (the air hole is opposite to the air hole of the ink box, and after the ink box is correctly installed, the magnet can have relatively large suction force so as to check whether the ink box is installed or not)
(4) Cleaning an ink-jet head of a microelectronic printer: before printing begins, a clean cotton core is installed. The waveform file of the printing ink is selected as 'Test 12', the number of printing holes required is selected, the 'cleaning' button is clicked, at the moment, the printer can be observed to start to automatically clean, and if the ink is observed to be sprayed out of the cleaning cotton core, the printing holes are indicated to be not blocked.
(5) Importing a printing graph: in the "device design" window, an inkjet printed document is newly created, and three electrodes drawn by CAD software are imported, and appropriate size and layout are adjusted.
(6) Printing is started: the photographic paper is placed in the printer, and the adsorption button is turned on (the photographic paper is fixed on the printing platform to prevent the photographic paper from sliding during printing). After checking each part again and without problems, clicking the print button, checking three options of printing hole selection, ink selection and adsorption selection, checking without errors, clicking the confirm button, and starting printing. At this time, the printer is automatically cleaned once, and a print progress window appears on the computer.
(7) And (3) printing is finished: the waiting process window displays "completed" indicating that printing is ended. Taking out the photographic paper and the ink box, and displaying printed three-electrode patterns on the photographic paper.
(8) Disassembling and assembling the ink box: following the reverse procedure to the "mount cartridge" operation.
(9) Shutdown operation: and (3) disconnecting the computer from the printer, closing the air pump, and closing the power supply of the computer.
3. Preparation and encapsulation of carbon-based electrode
After the carbon-based electrode printing in the above steps is completed, the printed electrode is cut to a proper size. The needle of the 0.25 μm filter needle tube was used to dip ink from the appropriate amount of silver/silver chloride ink and spread evenly over the printed reference electrode tip. And after the silver/silver chloride solution is naturally dried, the ink is solidified. At this time, a piece of adhesive tape with a fixed size can be cut and stuck on the lead part of the three electrodes, so that the whole electrode is prepared and packaged. The electrode prepared is shown in fig. 1.
4. Electrochemical testing
The electrode sheet was placed in an electrode holder of a portable device and immersed in an electrolyte, the supporting electrolyte being a Phosphate Buffered Solution (PBS) containing Na2HPO4, naH2PO4 and NaCl at different pH. CV is carried out in a potential range of-0.2V-0.7V/-0.3V-0.6V, and the sweeping speed is 100mV/s. The potential window of DPV is-0.4V-0.6V, the pulse width is 0.2s, and the pulse amplitude is 0.01V. The complete procedure of the experiment is shown in figure 2.
By SEM testing we obtained a microscopic topography image of the carbon-based ink. As can be seen from fig. 16, the carbon ink particles formed by ink jet on the photographic paper substrate are small in size, smooth in surface and regular in shape. It is illustrated that in the inkjet printing process, carbon-based inks are used to interact with the media to obtain the final print shape effect. It is apparent from the image that the carbon-based electrode surface aggregates to form non-uniformly shaped graphite blocks, with irregularly shaped protrusions and depressions that may affect the diffusivity and permeability of ink on photographic paper. The roughness of the electrode boundary formation may be related to the porosity of the paper, such that carbon-based ink can penetrate into the pores of the substrate, which increases the electroactive area of the electrode.
The structural characteristics of the carbon-based ink can be further understood by raman spectrum analysis. Two characteristic peaks, one at 1400cm-1 and the other at 1598cm-1, corresponding to the D and G peaks, respectively, are evident in FIG. 17. The D peak is mainly derived from the stretching vibration of the C-C bond and the c=c double bond. And the G peak is mainly derived from the stretching vibration of sp2 hybridized carbon atom and pi electrons [21]. From the ID/IG ratio shown of 0.84, it can be inferred that the analyzed carbon-based electrode has a high degree of defects and disorder. Further, more information about the c—c bond and c=c bond vibration modes, such as buckling, symmetrical stretching, asymmetrical stretching, and the like, can also be obtained from the peak shapes and positions of the D peak and the G peak. Therefore, the Raman spectrum analysis has important significance for researching the structure and the property of the carbon-based material, and provides an important reference for further exploring the performance of the carbon-based material. The Raman characterization and analysis of the ink-jet printing carbon ink plays an important role in the formulation and quality control of the ink.
In electrochemical detection, the potential response value of the electrode surface is changed due to the influence of different pH values of the buffer solution, so that the detection effect of HQ is influenced. In an acidic environment, the hydroxyl groups of HQ will protonate to positively charged ions, while in an alkaline environment, hydrogen ions will be lost to negatively charged ions. Fig. 3 and 4 show that HQ can exhibit a strong electric signal and has excellent detection sensitivity when the pH is about 6.5. Thus, ph=6.5 was chosen as the optimal buffer pH condition in combination with experimental results, and subsequent testing was performed under this condition.
The enrichment time and the enrichment potential are two important factors influencing the HQ detection result, and DPV is utilized to explore the influence of the enrichment potential and the enrichment time on the HQ electrochemical detection. At different enrichment potentials, the oxidation degree of HQ will change, thereby generating different electrochemical signals. As can be seen from the graph of fig. 5A, in the range of-0.3V to 0V, the oxidation peak current gradually increases with an increase in potential; in the range of 0V to 0.3V, the peak current gradually decreases with increasing potential, and the optimum enrichment potential is at 0V. As the enrichment potential continues to rise, the influence degree of the interferents also gradually increases, thereby reducing the detection effect of HQ.
Under the condition of fixed enrichment potential, more HQ is extracted to the surface of the electrode along with the extension of enrichment time, so that electrochemical signals are enhanced, and the detection sensitivity is improved. As can be seen from the graph of FIG. 5B, the current intensity is proportional to the enrichment time in the enrichment time range of 0s-250s, indicating that the detection effect of HQ is optimal at this time. When the enrichment time exceeds 250s, the response current gradually flattens, indicating that 250s is the optimal enrichment time. The enrichment time is further prolonged, so that other interferents are formed on the surface of the electrode, the duty ratio of the HQ signal is reduced, and the accuracy of a detection result is affected.
The scanning rate is an important parameter in the electrochemical detection of HQ, and represents the potential change rate achieved by potential scanning in unit time, and cyclic voltammograms at different scanning rates can show different potential and current change modes. In general, as the scan rate increases, the potential of the HQ oxidation or reduction peak tends to shift in the positive direction. This is because as the scanning rate increases, the rate of oxidation or reduction reaction increases, resulting in a shift of the peak potential in the positive direction, and the magnitude of the peak current also changes accordingly. Fig. 6 shows CV curves of HQ on carbon-based ink electrodes at different scan rates (v), and shows that the oxidation peak current (ipa) and the reduction peak current (ipc) are linearly related to the scan rate, see fig. 7, and the linear equation is as follows.
ipa＝106.5485ν(mV/s)+x+18.0225(R 2 ＝0.9926)
ipc＝-345.1756ν(mV/s)-26.7649(R 2 ＝0.9902)
The above equation shows that ipa and ipc are each in good linear relationship with v, indicating that the reaction of HQ on the carbon-based ink electrode is controlled by the adsorption process. In a certain range, as the scanning rate increases, the detection sensitivity of HQ increases, however, when the scanning rate further increases, the oxidation or reduction kinetic reaction rate of HQ cannot keep pace with the scanning rate, resulting in an increase in peak width and blurring of peak potential, thereby resulting in a loss of accuracy of the detection result.
Under the optimal conditions (pH is 6.5, enrichment potential is 0V, enrichment time is 250s, sweep speed is 100 mV/s), and the relationship between HQ of different concentrations and oxidation peak current is studied by adopting a DPV method. As shown in fig. 8 and 9, the response current and the HQ concentration are positively correlated within a certain range, and the linear equation is shown as follows.
ipa(μA)＝0.27C HQ (μM)+0.37(R 2 ＝0.9944，1nM-1μM)
ipa(μA)＝0.029C HQ (μM)+2.94(R 2 ＝0.9937，1μM-300μM)
The sensor has a linear range of HQ detection of 0.001-300 μm, wherein the first linear range is 0.001-1 μm, the second linear range is 1-300 μm, and the detection limit LOD is 0.33nM (S/N=3) according to calculation.
As shown in fig. 10A, in order to test the reproducibility of the sensor, eight paper-based electrodes were prepared by the same method and DPV test was performed on HQ of 10 μm, respectively, to obtain respective response currents, and RSD was calculated to be 10.8%. In addition, in order to evaluate the reproducibility of individual electrodes, the modified electrode was placed in a supporting electrolyte containing 10 μm HQ, which was subjected to 6 parallel experiments with DPV (fig. 10B), and the peak current variation of the obtained HQ response was small, and RSD was 2.2%, which indicates that the constructed sensor had good reproducibility and reproducibility.
In order to test the reliability and feasibility of the sensor in actual water sample detection, two environmental water samples near schools are detected by adopting a standard addition method. Firstly, filtering an acquired environmental water sample, diluting the filtrate by 50 times with PBS (phosphate buffer solution) with the pH of 6.5 to obtain a blank real sample solution, then adding different amounts of standard HQ into the blank solution to obtain 3 standard samples, carrying out DPV (differential pressure v) test by adopting a constructed paper-based sensor, recording the obtained current value, and calculating the content of the HQ through the standard curve. The experimental results showed that the recovery of HQ was 98.3% -104.7% which confirms that the sensor has satisfactory reliability.
Table 1 analysis results of sensor on HQ detection in actual sample (n=3)
In order to further verify the accuracy of the sensor in actual detection, an ultraviolet-visible spectrophotometer is used for performance comparison with the sensor. First, HQ standard solutions of different concentration gradients were prepared, tested by uv-vis spectrometry, linear relationship between absorbance at 288nm and HQ concentration was obtained, and standard curves were plotted (fig. 11-15), the linear equations being shown below.
Abs＝0.0064C HQ(μM)-0.035(R 2 ＝0.9994，10μM-80μM)
Then, a blank sample and a standard sample which are consistent with the detection of the sensor sample are removed for ultraviolet detection, and the obtained absorbance is used for calculating the concentration of HQ through an ultraviolet standard curve (fig. 13-15). Comparing the results obtained with the sensor with the results obtained with the uv-vis spectrophotometer, the experimental results showed that the HQ concentrations obtained with both methods were very close, indicating that the sensor had excellent accuracy (fig. 15). In addition, compared with an ultraviolet-visible spectrophotometer, the sensor has lower detection limit and wider linear range, and can replace a large-scale instrument such as the ultraviolet-visible spectrophotometer under certain conditions.
The present embodiment is only for explanation of the present invention and is not to be construed as limiting the present invention, and modifications to the present embodiment, which may not creatively contribute to the present invention as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present invention.
Claims (6)
1. The preparation method of the paper-based flexible electrode for detecting hydroquinone in the environmental water sample is characterized by comprising the following steps:
s1: drawing a three-electrode model;
s2: printing a paper-based electrode;
s3: preparing and packaging a carbon-based electrode;
s4: and (5) electrochemical testing.
2. The method for preparing the paper-based flexible electrode for detecting hydroquinone in an environmental water sample, which is characterized in that in the step S1, firstly, a basic frame at the lower part of an electrode in a three-electrode system is drawn, then, the top of a working electrode is drawn, the drawing of the frame is completed, two concentric circles with proper sizes are drawn as arc parts of a counter electrode and a reference electrode by taking the circle center of the circle at the top of the working electrode as a reference, finally, a deleting tool is selected, redundant parts are wiped, the outline is filled, and whether all dimension parameters meet the requirements is checked, so that the drawing is completed; the first electrode after drawing is used as the reference, the electrodes are copied in batches, so that the electrodes are orderly arranged on photographic paper, the patterns are ensured to be fully paved on the paper, and enough cutting gaps are reserved; and outputting the data, uploading the data to operation software of the microelectronic printer, checking whether each parameter is qualified again, and preparing for printing.
3. The method for preparing the paper-based flexible electrode for detecting hydroquinone in an environmental water sample as claimed in claim 1, wherein the printing of the paper-based electrode in the step S2 comprises the following steps:
(1) Turning on a power supply of the microelectronic printer; regulating the air pump pressure to 0.45Mpa, and opening a switch of the air pump to a first gear; opening software of the microelectronic printer, connecting the computer with the printer, and automatically performing zero setting and part resetting on the printer after the connection is completed;
(2) Opening the ink bag cover, and injecting a proper amount of printing test ink into the ink bag by using a circular needle; taking out the ink-jet printing head, lightly touching the silicon chip part of the printing head by using the dust-free paper which is wet by alcohol, and sucking excessive alcohol by using the clean dust-free paper; taking out the ink box, and assembling the ink jet head and the ink bag;
(3) Placing the assembled ink box in an ink box mounting position in a printer;
(4) Before printing starts, a clean cotton core is installed; selecting a waveform file corresponding to the printing ink and the number of printing holes required, clicking a cleaning button to start cleaning;
(5) Leading in three drawn electrodes, and adjusting proper size and typesetting;
(6) Putting photographic paper in the printer, and opening an adsorption button; clicking a print button to check three options of printing hole selection, ink selection and adsorption selection, checking without errors, and clicking a start print;
(7) Waiting for the process window to display 'completed', indicating that printing is finished; taking out the photographic paper and the ink box, and displaying printed three-electrode patterns on the photographic paper; disassembling and assembling the ink cartridge according to the reverse step of the 'mounting ink cartridge' operation; and (3) disconnecting the computer from the printer, and closing the printer, the air pump and the computer power supply.
4. The method for preparing the paper-based flexible electrode for detecting hydroquinone in an environmental water sample, as claimed in claim 1, wherein after printing the carbon-based electrode, the printed electrode is cut into a proper size; dipping a proper amount of Ag/AgCl ink by using a needle head of a 0.25 mu m filtering needle tube, and uniformly smearing the needle head on the end of a printed reference electrode; naturally drying the Ag/AgCl ink, and completing the solidification; at this time, a piece of adhesive tape with a fixed size is cut and stuck on the lead part of the three electrodes, and the whole electrode is prepared and packaged.
5. The method for preparing the paper-based flexible electrode for detecting hydroquinone in an environmental water sample, as claimed in claim 1, wherein, when the electrochemical test is carried out, the electrode sheet is placed in an electrode holder of a portable device and immersed in electrolyte, and the supporting electrolyte is Phosphate Buffer Solution (PBS) containing Na2HPO4, naH2PO4 and NaCl with different pH values; CV is carried out within a potential range of-0.2V-0.7V/-0.3V-0.6V, and the sweeping speed is 100mV/s; the potential window of DPV is-0.4V-0.6V, the pulse width is 0.2s, and the pulse amplitude is 0.01V.
6. The paper-based flexible electrode for detecting hydroquinone in an environmental water sample, which is prepared by the preparation method of the paper-based flexible electrode for detecting hydroquinone in an environmental water sample.
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