CN102608086A - Method for detecting melamine in milk on basis of inner-filter effect of fluorescence between CdTe quantum dots and AuNPs - Google Patents
Method for detecting melamine in milk on basis of inner-filter effect of fluorescence between CdTe quantum dots and AuNPs Download PDFInfo
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- CN102608086A CN102608086A CN2012100081122A CN201210008112A CN102608086A CN 102608086 A CN102608086 A CN 102608086A CN 2012100081122 A CN2012100081122 A CN 2012100081122A CN 201210008112 A CN201210008112 A CN 201210008112A CN 102608086 A CN102608086 A CN 102608086A
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Abstract
The invention relates to a method for detecting melamine in milk on the basis of inner-filter effect (IFE) of fluorescence between thioglycollic acid (TGA)-modified CdTe quantum dots and citric acid ligand coated gold nanoparticles (AuNPs), belonging to the field of analytical chemistry. The method comprises the following steps: preparing the AuNPs; synthesizing the TGA-CdTe quantum dots, and purifying; pretreating the milk sample; and detecting melamine in the milk. The invention can be used for detecting melamine in milk in a simple, quick and sensitive way on the basis of the following principle: the AuNPs can cause fluorescence quenching of the CdTe quantum dots, and the melamine can induce the aggregation of the AuNPs, so that the fluorescence intensity of the CdTe quantum dots is recovered. Thus, the invention provides convenience for the supervision and control of the dairy product industry.
Description
Technical field
Melamine detection method in the milk of the fluorescence inner filtering effect (IFE) between the golden nanometer particle (AuNPs) that the CdTe quantum dot of modifying based on TGA (TGA) and citric acid part coat and foundation belongs to technical field of analytical chemistry.
Background technology
The chemical name of melamine (melamine) is 2,4,6-triamido-1,3,5-triazines, and its structural formula is following:
It is a kind of important azacyclo-Organic Chemicals, can be used for producing melamine formaldehyde resin.
Because its nitrogen content is up to 66%, and the common Kjeldahl that adopts can't be discerned the source of nitrogen element in the food inspection, so it is often added in food and the animal feed to improve protein content artificially.
The acute oral toxicity of melamine is not strong, but melamine can form insoluble crystallization with its concurrent cyanuric acid in kidney.The long-term melamine of taking in high concentration can cause kidney failure even death, and is especially very big to children and teenager's harm.
In September, 2008; A plurality of provinces and cities such as Gansu, Jiangsu concentrate and baby's calculus incident occurs, find that with " Invest, Then Investigate " infant has the history of edible Sanlu board baby formula milk powder more, investigates through relevant departments; Find that there are serious quality problems in the Sanlu board baby formula milk powder that the said firm produces; Sanlu Group sends and recalls subsequently, claims that milk powder receives the pollution of melamine, and the Sanlu board baby milk powder of producing in the past on August 6th, 2008 is recalled in decision immediately.Then, other brand milk powder of some domestic productions have in the food of dry milk component with part and have also detected melamine successively, cause the sincere crisis of Chinese dairy products industry, also bring huge negative to daily life.
At present, the method for detection melamine mainly contains high performance liquid chromatography, liquid chromatography tandem mass spectrometry, gas chromatography tandem mass spectrometry, enzyme linked immunosorbent assay (ELISA) and capillary electrophoresis etc.These methods have higher sensitivity and accuracy preferably, but its pre-treatment step is complicated, consuming time, and need the operative skill of expensive equipment and specialty, so its widespread use is restricted.In recent years; Electrochemical method, SERS (SERS), infrared spectrum; Also be used to detect melamine successively based on the additive methods such as colorimetric sensor that gather the hexadine liposome, but these methods also are subject to complicated chemosynthesis, expensive or muting sensitivity etc.Therefore be badly in need of exploitation a kind of quick, easy, sensitive, detection method is used to detect melamine cheaply.
Chinese government regulation: melamine allows residual quantity to be respectively 1.0 and 2.5mg/kg in baby milk powder and maximum in other daily bread.
Summary of the invention
The method that the purpose of this invention is to provide the IFE between the AuNPs that a kind of CdTe quantum dot of modifying based on TGA and citric acid part coat and set up is used for fast, detects simply, delicately the content of milk melamine.
Technical matters: the IFE between the AuNPs that CdTe quantum dot of modifying based on TGA and citric acid part coat and melamine detection method in the milk set up; Its characteristics are that AuNPs can cause the fluorescent quenching of CdTe quantum dot; And melamine can induce AuNPs to assemble; The fluorescence intensity of CdTe quantum dot is restored, and then can detects the melamine in the milk through the variation of observing the system fluorescence intensity.
Technical scheme of the present invention:
May further comprise the steps: the preparation of AuNPs; Synthetic and the purifying of TGA-CdTe quantum dot; The spectral characterization of AuNPs and CdTe quantum dot; The AuNPs transmission electron microscope characterizes; Variable concentrations AuNPs is to the influence of CdTe quantum dot fluorescence intensity; The optimization of AuNPs concentration; The foundation of detection method; Different interfering materials are to the interference experiment of system; Detect the melamine in the milk.
(1) preparation of AuNPs:
Glassware used in the experiment all soaks 24h with chloroazotic acid, and redistilled water cleans, dry for standby, and the used distilled water of reagent preparation need be through the membrane filtration of 0.45 μ m; During preparation, in there-necked flask, add the gold chloride 50mL of 1mmol/L, heating makes its boiling under condition of stirring, adds the trisodium citrate 5mL of 38.8mmol/L fast; Heat while stirring, solution is by the faint yellow claret that becomes, and reaction continues 10min; Stop heating, continue to stir 10min, after solution is cooled to room temperature; With the micro-pore-film filtration of 0.45 μ m, 4 ℃ of preservations, prepared AuNPs particle diameter is 13nm; The AuNPs that makes is for use with pure water dilution in 1: 1 by volume, and the concentration after the dilution is 4.7 * 10
-7Mol/L.
(2) the synthetic and purifying of TGA-CdTe quantum dot:
At first weighing 0.0256gTe powder and 0.0386gNaBH
4Join in the there-necked flask, with the NaOH solution 100mL of high purity water preparation pH=11, to wherein feeding 10minN
2, be loaded on a constant voltage titration funnel 1. in, using the high purity water compound concentration is 4 * 10
-3The CdCl of mol/L
2Solution 100mL adds 67 μ LTGA, regulates pH=11 with the NaOH solution of 1mol/L, to wherein feeding 10minN
2, with the clear solution that obtains be loaded on another constant voltage titration funnel 2. in, with whole device and vacuum, N
2System couples together, and experience vacuumizes and logical N several times
2Step remove the O in the system
21. heated opens funnel, adds 3～5 and drips electromagnetic agitation; Te powder fundamental reaction back (solution is that redness and black powder disappear) is fully treated in initiation reaction, and the water is 1. all added; Obtain transparent light red solution, more 2. middle solution is all added, whole process is all carried out N
2Protection; Solution all adds continued and stirs 10min, removes N
2Protection is carried out the crystal growth reaction with the mixed solution that obtains with 50% microwave power output heating; The product that obtains adds isopyknic washed with isopropyl alcohol, and the centrifugal excess precursor of removing, and at last it is dispersed in the pure water of 200mL again; The CdTe quantum dot that makes is for use with pure water dilution in 1: 9 by volume, and the concentration after the dilution is 3.60 * 10
-6Mol/L.
(3) spectral characterization of AuNPs and CdTe quantum dot:
Adopting the UV-2550 ultraviolet. visible spectrophotometer (day island proper Tianjin company) is measured the ultraviolet-visible absorption spectroscopy of AuNPs and CdTe quantum dot respectively; Adopt the fluorescence spectrum of RF-5301 fluorophotometer (day island proper Tianjin company) when the measurement excitation wavelength is 450nm.
(4) the AuNPs transmission electron microscope characterizes
AuNPs and AuNPs-melamine are dripped respectively on the copper mesh that is coated with carbon film, and after room temperature was dried, with its size of TEcNAI F20 transmission electron microscope observing and pattern, accelerating potential was 200kV.
(5) variable concentrations AuNPs is to the influence of cdTe quantum dot fluorescence intensity:
The AuNPs (a, the 0 μ L that in 9 test tubes (5.0mL), add different amounts earlier successively; B, 100 μ L; C, 200 μ L; D, 300 μ L; E, 400 μ L; F, 500 μ L; G, 600 μ L; H, 700 μ L; I, 800 μ L), add pure water more respectively and be settled to 2mL, make potpourri react 10min down at 25 ℃, add 3.6 * 10 at last
-6The CdTe quantum dot 1mL of mol/L measures its fluorescence spectrum.
(6) optimization of AuNPs concentration:
Get 33 test tubes (5.0mL) and be divided into 3 groups, 11 every group; In 3 groups of test tubes, add 500 μ L, 800 μ L, 960 μ L AuNPs respectively; 1.-
melamine that adds variable concentrations more successively to each group in number test tube; Make it reach certain ultimate density (a, 0 μ g/L respectively; B, 10 μ g/L; C, 20 μ g/L; D, 30 μ g/L; E, 40 μ g/L; F, 50 μ g/L; G, 60 μ g/L; H, 70 μ g/L; I, 80 μ g/L; J, 90 μ g/L; K, 100 μ g/L), make potpourri react 10min down at 25 ℃, add CdTe quantum dot 1mL at last, measure its fluorescence spectrum.
(7) foundation of detection method:
In 11 test tubes (5.0mL), add 800 μ L AuNPs respectively earlier, add the melamine of variable concentrations more successively, make it reach certain ultimate density (a, 0 μ g/L respectively; B, 10 μ g/L; C, 20 μ g/L; D, 30 μ g/L; E, 40 μ g/L; F, 50 μ g/L; G, 60 μ/L; H, 70 μ g/L; I, 80 μ g/L; J, 90 μ g/L; K, 100 μ g/L), make potpourri react 10min down at 25 ℃, add CdTe quantum dot 1mL at last, measure its fluorescence spectrum.
(8) different interfering materials are to the interference experiment of system:
Respectively different interfering materials is joined in the AuNPs-CdTe system of the melamine that contains 50 μ g/L, by the said detection method of claim 8, measure fluorescence spectrum: the concentration of each interfering material is respectively Cobastab
1(0.44gL
-1), glucose (30gL
-1), threonine (143gL
-1), K
+(143gL
-1), Na
+(43gL
-1), Cl
-(141gL
-1), NO
3 -(150gL
-1), tryptophane (7-5gL
-1), glycocoll (7.5gL
-1), lysine (14gL
-1), histidine (7.5gL
-1), vitamin C (1gL
-1), Mg
2+(1gL
-1), Ca
2+(5.65gL
-1), lactose (25gL
-1), PO
4 3-(10gL
-1).
(9) melamine in the detection milk:
The melamine of variable concentrations is joined in the milk, make melamine wherein reach certain ultimate density (a, 0mg/L respectively; B, 0.1mg/L; C, 0.2mg/L; D, 0.3mg/L; E, 0.4mg/L; F, 0.5mg/L; G, 0.6mg/L; H, 0.7mg/L; I, 0.8mg/L; J, 0.9mg/L; K, 1.0mg/L; 1,1.1mg/L); In the centrifuge tube of 10mL, in the above-mentioned different milk of 2mL, add the water of 2mL, the chloroacetic acid of 1mL and the chloroform of 1mL respectively then, whirlpool concussion 1min; With protein precipitation; And the organism in the dissolved matrix, sonicated 15min then, the centrifugal 10min precipitation separation of 12000rmp; The supernatant of 2mL is transferred in another centrifuge tube, used the Na of 1M
2CO
3Adjustment pH is 8.0, and solution is removed deposition at the centrifugal once more 10min of 10000rmp; Supernatant filters with 0.45 μ m GTTP (polycarbonate leaching film), respectively gets 300 μ L final solutions, by the said detection method of claim 8, joins in the detection architecture, measures fluorescence spectrum separately.
Beneficial effect of the present invention: the present invention has prepared a kind of AuNPs of citric acid part coating and the CdTe quantum dot that a kind of TGA modifies; And set up a kind of method that can detect melamine in the milk quick, easy, sensitive, at low cost, for the supervision of dairy industry from now on provides convenience.
Description of drawings
The ultraviolet-visible absorption spectroscopy of Fig. 1 a:AuNPs; The fluorescence spectrum of b:TGA-CdTe quantum dot; The ultraviolet-visible absorption spectroscopy of c:TGA-CdTe quantum dot.
Fig. 2 transmission electron microscope photo: (A) AuNPs; (B) AuNPs-melamine; Illustration is the AuNPs of scale when being 20nm among the A.
There is the fluorescence spectrum of CdTe quantum dot down in Fig. 3 variable concentrations AuNPs.AuNPs concentration is respectively 0,0.16,0.32,0.48,0.6,0.72,0.88,1.0,1.25 * 10 among the a-i
-7Mol/L; CdTe quantum dot: 1.2 * 10
-7Mol/L.
The fluorescence response value of Fig. 4 CdTe quantum dot in containing the AuNPs-melamine system of variable concentrations.AuNPs●：0.8×10
-7mol/L■：1.25×10
-7mol/L▲：1.5×10
-7mol/LCdTe?1.2×10
-7mol/L
Fig. 5 variable concentrations melamine is to the influence of AuNPs-CdTe system fluorescence intensity.Melamine concentration is respectively 0,10,20,30,40,50,60,70,80,90,100 μ g/L among the a-k; AuNPs:1.25 * 10
-7Mol/L; CdTe quantum dot: 1.2 * 10
-7Mol/L.
The fluorescence spectrum of system when the different interfering materials of Fig. 6 (A) exist; (B) different interfering materials are to the influence of system.Interfering material: Cobastab
1(0.44gL
-1), glucose (30gL
-1), threonine (143gL
-1), K
+(143gL
-1), Na
+(43gL
-1), Cl
-(141gL
-1), NO
3 -(150gL
-1), tryptophane (7.5gL
-1), glycocoll (7.5gL
-1), lysine (14gL
-1), histidine (7.5gL
-1), vitamin C (1gL
-1), Mg
2+(1gL
-1), Ca
2+(5.65gL
-1), lactose (25gL
-1), PO
4 3-(10gL
-1).Melamine: 50 μ g/L; AuNPs:1.25 * 10
-7Mol/; CdTe quantum dot: 1.2 * 10
-7Mol/L.
The typical curve that Fig. 7 actual sample detects.Among the a-1 melamine concentration be respectively 0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.0,1.1mg/L; AuNPs:1.25 * 10
-7Mol/; CdTe quantum dot: 1.2 * 10
-7Mol/L.
Fig. 8 mark-on reclaims experiment.
Embodiment
The preparation of AuNPs
Material/agent: available from the gold chloride and the trisodium citrate of Beijing Chemical Plant.
Method: glassware used in the experiment all soaks 24h with chloroazotic acid, and redistilled water cleans, dry for standby, and the used distilled water of reagent preparation need be through the membrane filtration of 0.45 μ m; During preparation, in there-necked flask, add the gold chloride 50mL of 1mmol/L, heating makes its boiling under condition of stirring, adds the trisodium citrate 5mL of 38.8mmol/L fast; Heat while stirring, solution is by the faint yellow claret that becomes, and reaction continues 10min; Stop heating, continue to stir 10min, after solution is cooled to room temperature; With the micro-pore-film filtration of 0.45 μ m, 4 ℃ of preservations, prepared AuNPs particle diameter is 13nm; The AuNPs that makes is for use with pure water dilution in 1: 1 by volume, and the concentration after the dilution is 4.7 * 10
-7Mol/L.
The result: characterize through transmission electron microscope, prepared gold nanometer particle grain size is 13nm, and favorable dispersibility, and particle diameter is even.
Synthetic and the purifying of TGA-CdTe quantum dot
Material/agent: available from Te powder, the NaBH of Chemical Reagent Co., Ltd., Sinopharm Group
4, TGA, CdCl
2NaOH available from the Beijing Chemical Plant.
Method: at first weighing 0.0256gTe powder and 0.0386gNaBH
4Join in the there-necked flask, with the NaOH solution 100mL of high purity water preparation pH=11, to wherein feeding 10minN
2, be loaded on a constant voltage titration funnel 1. in, using the high purity water compound concentration is 4 * 10
-3The CdCl of mol/L
2Solution 100mL adds 67 μ LTGA, regulates pH=11 with the NaOH solution of 1mol/L, to wherein feeding 10minN
2, with the clear solution that obtains be loaded on another constant voltage titration funnel 2. in, with whole device and vacuum, N
2System couples together, and experience vacuumizes and logical N several times
2Step remove the O in the system
21. heated opens funnel, adds 3～5 and drips electromagnetic agitation; Te powder fundamental reaction back (solution is that redness and black powder disappear) is fully treated in initiation reaction, and the water is 1. all added; Obtain transparent light red solution, more 2. middle solution is all added, whole process is all carried out N
2Protection; Solution all adds continued and stirs 10min, removes N
2Protection is carried out the crystal growth reaction with the mixed solution that obtains with 50% microwave power output heating; The product that obtains adds isopyknic washed with isopropyl alcohol, and the centrifugal excess precursor of removing, and at last it is dispersed in the pure water of 200mL again; The CdTe quantum dot that makes is for use with pure water dilution in 1: 9 by volume.
The result: prepared TGA-CdTe quantum point grain diameter is 2.6nm, and concentration is 3.60 * 10
-6Mol/L, and favorable dispersibility, particle diameter is even.
Research variable concentrations AuNPs is to the influence of the fluorescence spectrum of CdTe quantum dot
The golden nanometer particle of material/agent: 13nm; The CdTe quantum dot.
Method: the AuNPs (a, the 0 μ L that in 9 test tubes (5.0mL), add different amounts earlier successively; B, 100 μ L; C, 200 μ L; D, 300 μ L; E, 400 μ L; F, 500 μ L; G, 600 μ L; H, 700 μ L; I, 800 μ L), add pure water more respectively and be settled to 2mL, make potpourri react 10min down at 25 ℃, add 3.6 * 10 at last
-6The CdTe quantum dot 1mL of mol/L measures its fluorescence spectrum.
The result: the AuNPs of variable concentrations can make the fluorescence of CdTe quantum dot that quencher in various degree takes place.
The optimization of AuNJPs concentration
The golden nanometer particle of material/agent: 13nm; The CdTe quantum dot; Melamine solution.
Method: get 33 test tubes (5.0mL) and be divided into 3 groups, 11 every group; In 3 groups of test tubes, add 500 μ L, 800 μ L, 960 μ LAuNPs respectively; 1.-
melamine that adds variable concentrations more successively to each group in number test tube; Make it reach certain ultimate density (a, 0 μ g/L respectively; B, 10 μ g/L; C, 20 μ g/L; D, 30 μ g/L; E, 40 μ g/L; F, 50 μ g/L; G, 60 μ g/L; H, 70 μ g/L; I, 80 μ g/L; J, 90 μ g/L; K, 100 μ g/L), make potpourri react 10min down at 25 ℃, add CdTe quantum dot 1mL at last, measure its fluorescence spectrum.
The result: the result shows that the concentration of the righttest AuNPs is 1.25 * 10
-7Mol/L.
The optimization in reaction time
The golden nanometer particle of material/agent: 13nm; Melamine solution.
Method: the 1mg/L melamine is joined 1.25 * 10
-7In the AuNPs solution of mol/L, every at a distance from its absorption spectrum of 30s scanning.
The result: the result shows that optimum reacting time is 10min.
The optimization of pH
The golden nanometer particle of material/agent: 13nm; The CdTe quantum dot; Melamine solution.
Method: in 8 test tubes (5.0mL), add AuNPs, melamine and quantum dot successively, ultimate density is respectively 1.25 * 10
-7Mol/L, 50 μ g/L, 1.2 * 10
-6Mol/L.HCl or NaOH with 0.1mol/L regulate pH from 4 to 11, measure its fluorescence spectrum.
The result: the result shows that best pH is 8.
The foundation of detection method
The golden nanometer particle of material/agent: 13nm; The CdTe quantum dot; Melamine solution.
Method: in 11 test tubes (5.0mL), add 800 μ L AuNPs respectively earlier, add the melamine of variable concentrations more successively, make it reach certain ultimate density (a, 0 μ g/L respectively; B, 10 μ g/L; C, 20 μ g/L; D, 30 μ g/L; E, 40 μ g/L; F, 50 μ g/L; G, 60 μ g/L; H, 70 μ g/L; I, 80 μ g/L; J, 90 μ g/L; K, 100 μ g/L), make potpourri react 10min down at 25 ℃, add CdTe quantum dot 1mL at last, measure its fluorescence spectrum.
The result: the melamine of variable concentrations can make the fluorescence of AuNPs-CdTe system that recovery in various degree takes place, and this method can be used for the detection by quantitative of melamine.
Different interfering materials are to the interference experiment of system
The golden nanometer particle of material/agent: 13nm; The CdTe quantum dot; Melamine solution.
Method: respectively different interfering materials is joined in the AuNPs-CdTe system of the melamine that contains 50 μ g/L,, measure fluorescence spectrum by the said detection method of claim 8; The concentration of each interfering material is respectively Cobastab
1(0.44gL
-1), glucose (30gL
-1), threonine (143gL
-1), K
+(143gL
-1), Na
+(43gL
-1), Cl
-(141gL
-1), NO
3 -(150gL
-1), tryptophane (7.5gL
-1), glycocoll (7.5gL
-1), lysine (14gL
-1), histidine (7.5gL
-1), vitamin C (1gL
-1), Mg
2+(1gL
-1), Ca
2+(5.65gL
-1), lactose (25gL
-1), PO
4 3-(10gL
-1).
The result: the interfering material that possibly exist in the milk does not have influence to this detection method.
The milk actual sample is detected.
The golden nanometer particle of material/agent: 13nm; The CdTe quantum dot; Melamine solution; Chloroacetic acid, chloroform available from the Beijing Chemical Plant; The milk of buying on the local market.
Method: in the centrifuge tube of 10mL, in the milk of 2mL, add the water of 2mL respectively, the chloroacetic acid of 1mL and the chloroform of 1mL; Whirlpool concussion 1min, with protein precipitation, and the organism in the dissolved matrix; Sonicated 15min then, the centrifugal 10min precipitation separation of 12000rmp; The supernatant of 2mL is transferred in another centrifuge tube, used the Na of 1M
2CO
3Adjustment pH is 8.0, and solution is removed deposition at the centrifugal once more 10min of 10000rmp; Supernatant filters with 0.45 μ m GTTP polycarbonate leaching film and obtains final solution, is used for detection method described in the claim 6; When joining a certain amount of melamine in the milk, also take identical pre-service and analytical procedure with aforementioned process.
The result: among the present invention, detecting of melamine is limited to 0.02mg/L, and the range of linearity is 0.1～1.1mg/L, and recovery of standard addition is (103～104) %.
Claims (10)
1. melamine detection method in the milk of the fluorescence inner filtering effect (IFE) between the golden nanometer particle (AuNPs) that the CdTe quantum dot of modifying based on TGA (TGA) and citric acid part coat and foundation; Its characteristics are that AuNPs can cause the fluorescent quenching of CdTe quantum dot; And melamine can induce AuNPs to assemble; The fluorescence intensity of CdTe quantum dot is restored, and then the melamine in the above principle detection milk capable of using, may further comprise the steps: the preparation of AuNPs; Synthetic and the purifying of TGA-CdTe quantum dot; The spectral characterization of AuNPs and CdTe quantum dot; The AuNPs transmission electron microscope characterizes; Variable concentrations AuNPs is to the influence of CdTe quantum dot fluorescence intensity; The optimization of AuNPs concentration; The variable concentrations melamine is to the influence of AuNPs-CdTe system fluorescence intensity; Different interfering materials are to the interference experiment of system; Detect the melamine in the milk.
2. the method for claim 1, the preparation process of wherein said AuNPs is following:
Glassware used in the experiment all soaks 24h with chloroazotic acid, and redistilled water cleans, dry for standby, and the used distilled water of reagent preparation need be through the membrane filtration of 0.45 μ m; During preparation, in there-necked flask, add the gold chloride 50mL of 1mmol/L, heating makes its boiling under condition of stirring, adds the trisodium citrate 5mL of 38.8mmol/L fast; Heat while stirring, solution is by the faint yellow claret that becomes, and reaction continues 10min; Stop heating, continue to stir 10min, after solution is cooled to room temperature; With the micro-pore-film filtration of 0.45 μ m, 4 ℃ of preservations, prepared AuNPs particle diameter is 13nm; The AuNPs that makes is for use with pure water dilution in 1: 1 by volume, and the concentration after the dilution is 4.7 * 10
-7Mol/L.
3. the method for claim 1, wherein said TGA-CdTe quantum dot synthetic following with purification step:
At first weighing 0.0256g Te powder and 0.0386gNaBH
4Join in the there-necked flask, with the NaOH solution 100mL of high purity water preparation pH=11, to wherein feeding 10min N
2, be loaded on a constant voltage titration funnel 1. in, using the high purity water compound concentration is 4 * 10
-3The CdCl of mol/L
2Solution 100mL adds 67 μ L TGA, regulates pH=11 with the NaOH solution of 1mol/L, to wherein feeding 10min N
2, with the clear solution that obtains be loaded on another constant voltage titration funnel 2. in, with whole device and vacuum, N
2System couples together, and experience vacuumizes and logical N several times
2Step remove the O in the system
21. heated opens funnel, adds 3～5 and drips electromagnetic agitation; Te powder fundamental reaction back (solution is that redness and black powder disappear) is fully treated in initiation reaction, and the water is 1. all added; Obtain transparent light red solution, more 2. middle solution is all added, whole process is all carried out N
2Protection; Solution all adds continued and stirs 10min, removes N
2Protection is carried out the crystal growth reaction with the mixed solution that obtains with 50% microwave power output heating; The product that obtains adds isopyknic washed with isopropyl alcohol, and the centrifugal excess precursor of removing, and at last it is dispersed in the pure water of 200mL again; The CdTe quantum dot that makes is for use with pure water dilution in 1: 9 by volume, and the concentration after the dilution is 3.60 * 10
-6Mol/L.
4. the method for claim 1, the spectral characterization step of wherein said AuNPs and CdTe quantum dot is following:
Adopt UV-2550 ultraviolet-visible spectrophotometer (day island proper Tianjin company) to measure the ultraviolet-visible absorption spectroscopy of AuNPs and CdTe quantum dot respectively; Adopt the fluorescence spectrum of RF-5301 fluorophotometer (day island proper Tianjin company) when the measurement excitation wavelength is 450nm.
5. the method for claim 1, the step that wherein said AuNPs transmission electron microscope characterizes is following:
AuNPs and AuNPs-melamine are dripped respectively on the copper mesh that is coated with carbon film, and after room temperature was dried, with its size of TECNAI F20 transmission electron microscope observing and pattern, accelerating potential was 200kV.
6. the method for claim 1, wherein said observation variable concentrations AuNPs is following to the step of the influence of CdTe quantum dot fluorescence intensity:
The AuNPs (a, the 0 μ L that in 9 test tubes (5.0mL), add different amounts earlier successively; B, 100 μ L:c, 200 μ L; D, 300 μ L; E, 400 μ L; F, 500 μ L; G, 600 μ L; H, 700 μ L; I, 800 μ L), add pure water more respectively and be settled to 2mL, make potpourri react 10min down at 25 ℃, add 3.6 * 10 at last
-6The CdTe quantum dot 1mL of mol/L measures its fluorescence spectrum.
7. the method for claim 1, the optimization step of wherein said AuNPs concentration is following:
Get 33 test tubes (5.0mL) and be divided into 3 groups, 11 every group; In 3 groups of test tubes, add 500 μ L, 800 μ L, 960 μ L AuNPs respectively; 1.-
melamine that adds variable concentrations more successively to each group in number test tube; Make it reach certain ultimate density (a, 0 μ g/L respectively; B, 10 μ g/L; C, 20 μ g/L; D, 30 μ g/L; E, 40 μ g/L; F, 50 μ g/L; G, 60 μ g/L; H, 70 μ g/L; I, 80 μ g/L; J, 90 μ g/L; K, 100 μ g/L), make potpourri react 10min down at 25 ℃, add CdTe quantum dot 1mL at last, measure its fluorescence spectrum.
8. the method for claim 1, the step of the foundation of wherein said detection method is following:
In 11 test tubes (5.0mL), add 800 μ L AuNPs respectively earlier, add the melamine of variable concentrations more successively, make it reach certain ultimate density (a, 0 μ g/L respectively; B, 10 μ g/L; C, 20 μ g/L; D, 30 μ g/L; E, 40 μ g/L; F, 50 μ g/L; G, 60 μ g/L; H, 70 μ g/L; I, 80 μ g/L; J, 90 μ g/L; K, 100 μ g/L), make potpourri react 10min down at 25 ℃, add CdTe quantum dot 1mL at last, measure its fluorescence spectrum.
9. the method for claim 1, wherein said different interfering materials are following to the interference experiment step of system:
Respectively different interfering materials is joined in the AuNPs-CdTe system of the melamine that contains 50 μ g/L,, measure fluorescence spectrum by the said detection method of claim 8; The concentration of each interfering material is respectively Cobastab
1(0.44gL
-1), glucose (30gL
-1), threonine (143gL
-1), K
+(143gL
-1), Na
+(43gL
-1), Cl
-(141gL
-1), NO
3 -(150gL
-1), tryptophane (7.5gL
-1), glycocoll (7.5gL
-1), lysine (14gL
-1), histidine (7.5gL
-1), vitamin C (1gL
-1), Mg
2+(1gL
-1), Ca
2+(5.65gL
-1), lactose (25gL
-1), PO
4 3-(10gL
-1).
10. the method for claim 1, the step of the melamine in the wherein said detection milk is following:
The melamine of variable concentrations is joined in the milk, make melamine wherein reach certain ultimate density (a, 0mg/L respectively; B, 0.1mg/L; C, 0.2mg/L; D, 0.3mg/L; E, 0.4mg/L; F, 0.5mg/L; G, 0.6mg/L; H, 0.7mg/L; I, 0.8mg/L; J, 0.9mg/L; K, 1.0mg/L; 1,1.1mg/L); In the centrifuge tube of 10mL, in the above-mentioned different milk of 2mL, add the water of 2mL, the chloroacetic acid of 1mL and the chloroform of 1mL respectively then, whirlpool concussion 1min; With protein precipitation; And the organism in the dissolved matrix, sonicated 15min then, the centrifugal 10min precipitation separation of 12000rmp; The supernatant of 2mL is transferred in another centrifuge tube, used the Na of 1M
2CO
3Adjustment pH is 8.0, and solution is removed deposition at the centrifugal once more 10min of 10000rmp; Supernatant filters with 0.45 μ m GTTP (polycarbonate leaching film), respectively gets 300 μ L final solutions, by the said detection method of claim 8, joins in the detection architecture, measures fluorescence spectrum separately.
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