CN201811939U - Electrochemically modified electrode for detecting melamine and detecting device - Google Patents
Electrochemically modified electrode for detecting melamine and detecting device Download PDFInfo
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- CN201811939U CN201811939U CN2010202997661U CN201020299766U CN201811939U CN 201811939 U CN201811939 U CN 201811939U CN 2010202997661 U CN2010202997661 U CN 2010202997661U CN 201020299766 U CN201020299766 U CN 201020299766U CN 201811939 U CN201811939 U CN 201811939U
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- melamine
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- fdu
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Abstract
The utility model discloses a modified electrode for detecting melamine rapidly, which comprises a base electrode, a poly dimethyl diallyl ammonium chloride (PDDA) film and a formaldehyde-treated urea (FDU) film, wherein the PDDA film is arranged on the outer surface of the base electrode, and the FDU film is arranged on the outer surface of the PDDA film. The utility model further discloses a detecting device employing the modified electrode as an operating electrode. The modified electrode with high sensitivity is capable of detecting the melamine, and is made of environment-friendly materials so as to avoid pollution.
Description
Technical field
The utility model relates to analytical chemistry and detection range, and more specifically, the utility model relates to a kind of galvanochemistry modified electrode and pick-up unit that is used to detect melamine.
Background technology
Melamine is a raw material of making melamine formaldehyde resin (melamine plastics), and this resin also is commonly called as sometimes is melamine, is usually used in making daily utensil, decoration veneer, fabric finishing agent etc.The mensuration of protein content adopts Kjeldahl usually in the food industry at present, calculates Protein content in the food indirectly by the content of measuring nitrogen-atoms.Because comparing with protein (average nitrogen content 16%), melamine (nitrogen content 66%) has higher nitrogen content, so utilized by some lawless persons, be added in the food causing the higher illusion of content in food, and then cause serious food security accident.
From first " pet poison grain " disturbance of the U.S. in 2007, to " Sanlu milk powder " incident in 2008, melamine caused extensive concern.Food and agricultural organization in 2006 and World Health Organization's residues of pesticides joint conference issue, the long-term absorption of melamine will cause the infringement of reproduction, urinary system, forms bladder, kidney portion calculus, even can further bring out carcinoma of urinary bladder.According to the literature, melamine can be hydrolyzed into ammelide, ammeline and cyanuric acid under the environment of strong acid and strong base, is combined into insoluble material with cyanuric acid under the pH of urine, and this bond can crystallization and then injury tissue.
For fear of the generation once more of this type of accident, fast, accurately detecting of melamine becomes current great attention and problem demanding prompt solution in the food.Chromatography application in the detection that melamine detects at present is more, comprises high performance liquid chromatography-photodiode array detection method (HPLC-DAD), liquid chromatography-tandem mass spectrometry detection method (LC-MS/MS), gas chromatography-mass spectrum detection method (GC-MS) etc.Melamine detection national standard method promptly adopts HPLC, LC-MS/MS and GC-MS, GC-MS/MS that sample is detected in raw milk that China is existing and the dairy products.But the operating cost of chromatographic process and Mass Spectrometer Method is relative higher, and the processing procedure more complicated of sample, and is consuming time longer in actual analysis is measured, and therefore is necessary to study more efficient, quick, the sensitive analysis test method of foundation.In addition, utilization and the trial on melamine detects such as Capillary Electrophoresis-photodiode array detection method (CE-DAD), Capillary Electrophoresis-uv detection method (CE-UV), molecular imprinting method also is seen in one after another in all kinds of documents and materials.But exist shortcomings such as instrument costliness, detection time length, operating difficulties in the said method, therefore also exist certain deficiency in actual applications.
Electrochemical method is used widely in fields such as food security, life science and clinical medicine owing to advantages such as its instrument and equipment are simple, easy to make and with low cost.But on detection sensitivity, be still waiting further raising.Therefore, this area presses for a kind of high sensitivity, quick and convenient detection melamine detection electrode and pick-up unit.
Summary of the invention
In order to detect the melamine in milk etc. rapidly and sensitively, the utility model provides a kind of galvanochemistry modified electrode that is used for the fast detecting melamine.
Of the present utility modelly also provide a kind of electrochemical detection device that detects melamine.
The utility model first aspect provides a kind of galvanochemistry modified electrode that is used for the fast detecting melamine, and described electrode comprises:
-basal electrode;
-be arranged at the PDDA film of basal electrode outside surface; And
-be arranged at the FDU film of PDDA film outer surface.
Wherein, described basal electrode (1) is a glass-carbon electrode.
Second aspect of the present utility model provides a kind of electrochemical detection device that is used for the fast detecting melamine, and described pick-up unit is an electrolytic cell, and described electrolytic cell comprises: working electrode, to electrode and contrast electrode; Be arranged on the support at electrolytic cell top, described support is used to place described to electrode and contrast electrode; And the electrolytic solution that is arranged on the electrolytic cell bottom.
Its characteristics are that described working electrode adopts modified electrode, described modified electrode to comprise:
-basal electrode;
-be arranged at the PDDA film of basal electrode outside surface; And
-be arranged at the FDU film of PDDA film outer surface.
In the utility model, described basal electrode is a glass-carbon electrode.
In the utility model, described is platinum electrode to electrode.
In the utility model, described contrast electrode is the Ag/AgCl contrast electrode.
In the utility model, described electrolytic solution is for containing K
3[Fe (CN)
6] and the phosphate buffer of KCl.
The beneficial effects of the utility model are:
When (1) the utility model utilizes the FDU-15-Pt/PDDA/GCE modified electrode that melamine is carried out the Direct Electrochemistry detection, find in certain concentration range the concentration of melamine and [Fe (CN)
6]
3-/4The decrease of reduction peak current value has linear dependence, and detecting the range of linearity is 5.0 * 10
-9～1.4 * 10
-7Mol/L, detectability reaches 1.3 * 10
-9Mol/L.The preparation of FDU-15-Pt/PDDA/GCE modified electrode is simple, response speed is fast.
(2) the FDU-15-Pt/PDDA/GCE modified electrode also has good selectivity in the utility model, when the concentration of melamine is 1.0 * 10
-7During mol/L, 50 times Na
+, SO
4 2-, NH
4 +, CH
3COO
-And glucose does not have influence substantially to melamine detection.
(3) electrode preparation method of the present utility model and detection method are simple to operation, use the instrument low price, and be with low cost.
(4) electrode material of the present utility model is pollution-free, can not cause environmental pollution, meets people couple and environmental protection requirement.
Description of drawings
Fig. 1 is the structural representation of modified electrode of the present utility model.Wherein: 1 is basal electrode (glass-carbon electrode), and 2 is the PDDA molecular layer for what be coated on glass-carbon electrode 1 surface, 3 FDU molecular layers for modifying.4 is the utility model FDU-15-Pt/PDDA/GCE modified electrode 4.
Fig. 2 shows the structural representation of the utility model modified electrode.Wherein: 1 is basal electrode (glass-carbon electrode), the 2 PDDA molecular layers for modification, the 3 FDU-15-Pt molecular layers for modification.
Fig. 3 shows the structural representation of the utility model pick-up unit.Wherein: 4 are working electrode (being the modified electrode 4 that Fig. 1 shows), and 5 is to electrode, and 6 is the Ag/AgCl contrast electrode, and 7 is the detection cell container, and 8 is electrolytic solution, and 9 is electrode suppor.
The FDU-15-Pt/PDDA/GCE modified electrode of Fig. 4 (A) expression under different melamine concentration to [Fe (CN)
6]
3-/4-DPV response, horizontal ordinate is a current potential, ordinate is the current-responsive size.
Fig. 4 (B) expression FDU-15-Pt/PDDA/GCE modified electrode detects the working curve of melamine, and horizontal ordinate is the concentration of melamine, and ordinate is the value that reduces of current-responsive.
Embodiment
Below each side of the present utility model is described in detail.Following examples of the present invention are not limitation of the present invention.Therefore, under the spirit and scope that do not deviate from inventive concept, variation and advantage that those skilled in the art can expect all are included among the present invention, and are protection domain with claims.
Electronegative glass-carbon electrode can attract positively charged polyelectrolyte PDDA, can well adsorb mesoporous material FDU as the PDDA of stabilizing agent, so just can form stable FDU-15-Pt/PDDA/GCE modified electrode.Utilize cyclic voltammetric, differential pulse volt-ampere, AC impedance and transmission electron microscope to characterize to the electrochemical behavior of modified electrode and physical behavior etc.
Basal electrode
Basal electrode has been selected glass-carbon electrode (GCE) for use, and this is because the glass-carbon electrode surface is electronegative, is easy to combine with surperficial positively charged decorative material PDDA.
PDDA
The PDDA[diallyl dimethyl ammoniumchloride, poly (diallyl dimethylammonium) chloride] be a kind of water miscible positively charged polyelectrolyte, can combine effectively by electrostatic interaction with electronegative glass-carbon electrode surface, so PDDA is everlasting in the preparation of modified electrode as stabilizing agent and medium.
FDU
FDU is the mesoporous material with phenolics structure, has the advantage of mesoporous material and organic polymer concurrently, and not only structurally micropore is arranged in order, surface area is big, the Adjustable structure joint, has features such as high hydrophobicity and resistance to acids and bases simultaneously.Because the conductivity of FDU is low, not separately as the probe of electrochemical sensor, therefore needs modification to go up metal nanoparticle (as Pt, Pd etc.) and improve its electric conductivity usually.The FDU decorative material that is adopted in the utility model is FDU-15-Pt.
Modified electrode 4 among Fig. 1 obtains like this:
1) pre-service of glass-carbon electrode
Base electrode 1 (glass-carbon electrode) is used 03# sand paper, 0.3 and 0.05 μ m Al successively
2O
3After being polished to minute surface repeatedly on powder, the clean chamois leather of cleaning, flushing under water, successively through 0.2mol/L HCl solution, 0.2mol/L NaOH solution, ethanol, secondary deionized water supersound washing 5min, it is standby that electrode dries the back.
2) modification of PDDA
PDDA (20wt%, Sigma company, Germany) is modified to 0.5wt% with secondary deionized water.Place the PDDA solution after the dilution to soak 15 minutes at the GCE electrode after the above-mentioned processing, dry under infrared lamp the flushing back.
3) modification of FDU
FDU-15-Pt is provided by East China Normal University's Shanghai Green Chemistry and chemical process key lab.Taking by weighing the 10mg powder is scattered in pH 7.6 phosphate buffered solution of 1mL.The glass-carbon electrode of having modified PDDA is immersed in the dispersion liquid of above-mentioned FDU-15-Pt and soaked 20 minutes, the oven dry down of flushing back infrared lamp.
4) structure of FDU-15-Pt/PDDA/GCE modified electrode
The structure of the FDU-15-Pt/PDDA/GCE modified electrode 4 that said method obtains as shown in Figure 1, basal electrode is a glass-carbon electrode 1, what be coated on glass-carbon electrode 1 surface is PDDA molecular layer 2, outermost layer is a FDU-15-Pt molecular layer 3.
In the utility model, PDDA and FDU are modified the surface of basal electrode 1 successively, make described basal electrode 1 outside surface be coated with the PDDA film, described PDDA film 2 outside surfaces are coated with FDU film 3.As the melamine in the working electrode test sample, has the extremely excellent effect that detects with the modified electrode 4 of this structure of the utility model.
Adopt modified electrode 4 of the present utility model to detect melamine, be based on following principle:
Detection is to contain 1mmol/L K
3[Fe (CN)
6] and the phosphate buffered solution (pH 6.5) of 0.5mmol/L KCl in carry out K
3[Fe (CN)
6] play probe.The melamine molecule main body is the C-N heterocycle structure, contains three N atoms and connects three amino substituting groups, can be by the effect combination of N-H...N hydrogen bond between the adjacent molecule.In melamine and the interactional process of electrode modified material, melamine molecule enters in the hole of FDU-15-Pt, and hydroxyl generation hydrogen bond action structural with it formation supramolecular structure, thereby has stopped up the duct.K as probe
3[Fe (CN)
6] can't detect [Fe (CN) near glass-carbon electrode
6]
3-/4-Reduction peak current will reduce.Therefore can pass through [Fe (CN)
6]
3-/4-The decrease of reduction peak current detects melamine indirectly.
Fig. 2 has shown the structural representation of another embodiment of this modified electrode.Wherein: 1 is basal electrode (glass-carbon electrode), the 2 PDDA molecular layers for modification, the 3 FDU-15-Pt molecular layers for modification.Described basal electrode 1 is a planar structure.
As shown in Figure 3, pick-up unit comprises: 4 pairs of electrodes 5 of working electrode and contrast electrode 6 are arranged on the electrode suppor 9 at electrolytic cell 7 tops; And the electrolytic solution 8 that is arranged on electrolytic cell 7 bottoms.On electrode suppor 9, be distributed with modified electrode 4, to electrode 5 and contrast electrode 6.Also contain electrolytic solution 8 in electrolytic cell 7, content is as follows: 1mmol/L K
3[Fe (CN)
6] and the pH 6.5 of 0.5mmol/LKCl, the phosphate buffered solution of 0.05mol/L.The lower end of each electrode invades in the electrolytic solution, and the upper end links to each other with CHI832 electrochemical workstation (Shanghai occasion China instrument company) respectively.
The electrolytic solution of Fig. 3 is running like this:
In the electrolytic cell, be working electrode with modified electrode 4, the Ag/AgCl electrode is as contrast electrode 6, and the Pt electrode is set up three-electrode system as to electrode 5, is electrolytic solution 8 in the electrolytic cell.With electrochemical workstation three-electrode system is carried out the Data Control transmission, adopt the differential pulse voltammetry to survey melamine molecule.This detects potential window and is generally+0.60V～-0.30V.
Concrete testing process:
Detection method
Three-electrode system is adopted in experiment, and working electrode adopts the FDU-15-Pt/PDDA/GCE modified electrode, is platinum filament to electrode, and contrast electrode is Ag/AgCl electrode (saturated KCl), places liquid at the bottom of the test of the pH 6.5 that contains the finite concentration melamine.Before the mensuration, enrichment 30s under+0.80V constant potential; Differential pulse voltammetry (DPV) is adopted in experiment, the electric potential scanning scope from+0.60V～-0.30V, the peak current at record reduction peak place.According to the linear relationship between melamine concentration and the reduction peak current decrease, can carry out detection by quantitative to melamine.After each the use, electrode washing is clean with redistilled water.
Testing result
Under these conditions, utilize DPV to [Fe (CN) under the different melamine concentration
6]
3-/4-Reduction peak current detect [Fe (CN)
6]
3-/4-Peak current decrease (Δ i) is directly proportional with the concentration (c) of melamine, Fig. 4 (A), (B) be respectively prepared FDU-15-Pt/PDDA/GCE modified electrode under different melamine concentration to [Fe (CN)
6]
3-/4-DPV response and working curve.Represent among the figure, contain 1mmol/L K
3[Fe (CN)
6] and the PBS damping fluid of the pH 6.5 of 0.5mmol/L KCl in, a-j: the concentration of melamine is followed successively by: 0,5.0 * 10
-9, 1. * 10
-8, 2 * 10
-8, 3.0 * 10
-8, 4.0 * 10
-8, 6.0 * 10
-8, 1.0 * 10
-7, 1.2 * 10
-7,, 1.4 * 10
-7Mol/L.Can learn that from working curve the FDU-15-Pt/PDDA/GCE modified electrode is 5.0 * 10 to the melamine detection scope
-9～1.4 * 10
-7Mol/L, and follow following equation: Δ i=0.0085c+0.3527, linearly dependent coefficient is 0.9912, detectability reaches 1.3 * 10
-9Mol/L (signal to noise ratio (S/N ratio)=3: 1).
Melamine detection in the milk:
The pre-service of milk
This laboratory reference national standard " melamine detection method (22388-2008) in raw milk and the dairy products " is carried out pre-service to milk sample.Take by weighing 2g milk and place 50mL tool plug centrifuge tube, add 15mL trichloroacetic acid solution (1%) and 5mL acetonitrile.The ultrasonic 10min of mixed liquor is after 10min is extracted in vibration again, to be not less than the centrifugal 10min of 4000r/min.Supernatant is settled to 25mL with trichloroacetic acid solution behind the filter paper filtering of trichloroacetic acid solution-wet.Pipette 5mL filtrate, be concentrated into 5mL (being equivalent to the 0.4g sample) 50 ℃ of following nitrogen flushing behind the adding 5mL water mixing, standby behind 2 μ m acetate fiber membrane filtrations.
Melamine detection result in the milk
Therefore after testing, all do not detect melamine in the sample, adopt standard addition method, add in sample handle after with different volumes the melamine storing solution of identical dilute concentration after, get 10 μ L and add in the test solution and detect, the results are shown in Table 1.
Table 1.FDU-15-Pt/PDDA/GCE modified electrode is to the measurement result of melamine in the milk
Claims (5)
1. galvanochemistry modified electrode (4) that is used to detect melamine is characterized in that described modified electrode (4) comprising:
-basal electrode (1);
-be arranged at the PDDA film (2) of basal electrode (1) outside surface; And
-be arranged at the FDU film (3) of PDDA film (2) outside surface.
2. galvanochemistry modified electrode as claimed in claim 1 is characterized in that, described basal electrode (1) is a glass-carbon electrode.
3. one kind is used to detect the melamine detection device, it is characterized in that, described pick-up unit is electrolytic cell (7); Described electrolytic cell (7) comprising:
-working electrode; Described working electrode is a galvanochemistry modified electrode as claimed in claim 1 (4);
-to electrode (5);
-contrast electrode (6);
-being arranged on the support (9) at electrolytic cell (7) top, described support (9) is used to place described to electrode (5) and contrast electrode (6); And
-be arranged on the electrolytic solution (8) of electrolytic cell (7) bottom.
4. pick-up unit as claimed in claim 3 is characterized in that, described is platinum electrode to electrode (5).
5. pick-up unit as claimed in claim 3 is characterized in that, described contrast electrode (6) is the Ag/AgCl contrast electrode.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202997661U CN201811939U (en) | 2010-08-20 | 2010-08-20 | Electrochemically modified electrode for detecting melamine and detecting device |
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|---|---|---|---|
| CN2010202997661U CN201811939U (en) | 2010-08-20 | 2010-08-20 | Electrochemically modified electrode for detecting melamine and detecting device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102262115A (en) * | 2011-07-28 | 2011-11-30 | 南京师范大学 | Electrochemical immunosensor for melamine content determination, and preparation method and application thereof |
| CN105403604A (en) * | 2015-12-17 | 2016-03-16 | 河南省科学院能源研究所有限公司 | Metal nanoparticle/nanocellulose compound-based enzyme-free glucose electrochemical sensor, and preparation method thereof |
-
2010
- 2010-08-20 CN CN2010202997661U patent/CN201811939U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102262115A (en) * | 2011-07-28 | 2011-11-30 | 南京师范大学 | Electrochemical immunosensor for melamine content determination, and preparation method and application thereof |
| CN105403604A (en) * | 2015-12-17 | 2016-03-16 | 河南省科学院能源研究所有限公司 | Metal nanoparticle/nanocellulose compound-based enzyme-free glucose electrochemical sensor, and preparation method thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110427 Termination date: 20120820 |