CN110286225A - A kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system - Google Patents
A kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system Download PDFInfo
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Abstract
The invention belongs to technical field of food safety detection, construct a kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system；Method particularly includes: using the methyl alcohol mixed liquor of six water yttrium chlorides, six water ytterbium chlorides, six water holmium chlorides, six water gadolinium chlorides, oleic acid, 1- octadecylene, ammonium fluoride and sodium hydroxide as raw material, prepare up-conversion nano material；Ethyl alcohol, ammonium hydroxide, tetraethyl orthosilicate, 3- aminopropyl triethoxysilane is added, obtain amino functional up-conversion nano material, it is mixed with dithizone solution, obtain specific detection system, the fluorescence intensity signals characteristic value for detecting solution is measured after cadmium-ion solution is added, for ordinate, cadmium content examination criteria curve is established by abscissa of concentration of cadmium ions, realizes the measurement of Cadmium in Tea content to be measured；The present invention realizes highly sensitive, the specific detection of Cadmium in Tea by building stable state specificity cadmium ion fluorescent detection system, there is wider linear detection range and lower detection to limit, application prospect is good.
Description
Technical field
The invention belongs to technical field of food safety detection, and in particular to one kind is based on upper conversion and dithizone specificity body
The Cadmium in Tea detection method of content of system.
Background technique
China is Chan Cha big country, and tealeaves is the conventional outlet agricultural product in China, and reinforcement is to the control of quality and safety of tea
It ensures safe important measure of drinking tea, is also beneficial to improve the competitiveness in the international market of tea product.As modern industry is rapidly sent out
Exhibition, water body, air, soil all receive different degrees of heavy metal pollution.Tea tree being capable of absorbent earth in growth and development process
Heavy metal in earth, it is exceeded so as to cause the content of beary metal in tealeaves, such as cadmium, mercury, lead heavy metal.Cadmium is absorbed by the body
Afterwards, a kind of cadmium sulfoprotein can be formed in human body, and is gathered in liver, is directly detrimental to health.Long-term drinking cadmium content is super
Target tealeaves can cause human poisoning.China agricultural industry criteria NY659-2003 provides that the cadmium content in tealeaves is no more than
1mg/kg。
Traditional cadmium content detection method is atomic absorption spectrography (AAS), although Detection accuracy is high, instrument and equipment is high
It is expensive, testing cost is high, complex steps, detection time are long, be not able to satisfy the real-time quick testing requirements of cadmium content.The present invention proposes
A kind of fast and accurately cadmium content detection method, overcomes the shortcomings of conventional method, improves the sensitivity and accuracy of cadmium detection.
Summary of the invention
In view of the deficiencies of the prior art, present invention seek to address that one of described problem, provide it is a kind of based on upper conversion and
The Cadmium in Tea detection method of content of dithizone specificity system prepares fluorogenic donor, structure especially by the controllable self assembly of nanometer
The cadmium ion detection architecture of stable state specificity is built, the influence of background fluorescence, other ion interferences and millet paste color is eliminated, realizes tea
Inexpensive, the highly sensitive and specific detection of cadmium in leaf.
In order to achieve the goal above, the specific steps of the present invention are as follows:
Step 1, the preparation of up-conversion nano material: by six water yttrium chlorides, six water ytterbium chlorides, six water holmium chlorides and six
Water gadolinium chloride is added to ultrasonic dissolution in methanol A, is transferred in the mixed solution of oleic acid and 1- octadecylene；In argon gas protective condition
Under, the reaction of first time heating stirring is cooled to room temperature, obtains coolant liquid；After ammonium fluoride, sodium hydroxide and methanol B are mixed, add
Enter in coolant liquid, water-bath twice, makes methanol volatilize completely；Under the protection of argon gas, second of heating stirring reaction, it is cold
But to room temperature, reaction product is obtained；Reaction product is cleaned with the mixed liquor of ethyl alcohol and methylene chloride, vacuum drying obtains turning
Change nano material；
Step 2, the modification of up-conversion nano material: the up-conversion nano material that step 1 is obtained is added in ethyl alcohol,
Deionized water and ammonium hydroxide is added in ultrasonic disperse, be stirred to react for the first time；Tetraethyl silicate resin is added, is stirred for the second time
Mix reaction；3- aminopropyl triethoxysilane is added, carries out third time and is stirred to react, be cooled to room temperature, obtain reaction product；With
Ethyl alcohol and the mixed liquor of deionized water clean reaction product, and vacuum drying obtains amino functional up-conversion nano material；
Step 3, the building of specific detection system: the amino functional up-conversion nano material that step 2 is obtained is molten
In deionized water, amino functional up-conversion nano material solution is obtained, is then mixed with dithizone solution, amino function is obtained
Up-conversion nano material-dithizone mixed system, i.e. specific detection system can be changed；
The foundation of cadmium content examination criteria curve: the cadmium-ion solution of various concentration is added to step respectively by step 4
In three obtained specific detection systems, obtain detection solution, measurement detection solution fluorescence intensity signals characteristic value, with cadmium from
Sub- concentration is abscissa, and fluorescence intensity signals characteristic value is ordinate, establishes cadmium content examination criteria curve；
The detection of Cadmium in Tea content: step 5 tealeaves sample is smashed and is sieved, tea powder is obtained；Then by tea powder and dense
Nitric acid mixing carries out micro-wave digestion, and room temperature is cooling；Digestion solution is obtained, acid volatilization completely in digestion solution is made using oil bath, filters, adjusts
Digestion solution pH is saved, is added in the specific detection system that step 3 obtains, detection solution, the fluorescence of measurement detection solution are obtained
Strength signal characteristic value substitutes into the cadmium content examination criteria curve that step 4 obtains, calculates cadmium content in tealeaves sample.
Preferably, in step 1, the six water yttrium chloride, six water ytterbium chlorides, six water holmium chlorides, six water gadolinium chlorides, methanol A
Amount ratio be 0.087g:0.047g:0.005g:0.066g:3mL；The time of the ultrasonic dissolution is 5-10min；Described
Primary heating is stirred to react, and temperature is 150-170 DEG C, time 30min；Second of heating stirring reaction, temperature are
290-310 DEG C, time 1h；The volume ratio of the methanol A, oleic acid and 1- octadecylene are 3:4.5:10.5；
The methanol A, ammonium fluoride, sodium hydroxide, methanol B amount ratio be 3mL:0.221g:0.45g:15mL；The second
The volume ratio of pure and mild methylene chloride mixed liquor, ethyl alcohol and methylene chloride is 1:2；The water-bath is for the first time 45-55 twice
DEG C water-bath 30min, second is 75-85 DEG C of water-bath 40min.
Preferably, in step 2, the conversion nano material, ethyl alcohol, deionized water, ammonium hydroxide, tetraethyl silicate resin and 3-
The amount ratio of aminopropyl triethoxysilane is 10mg:6mL:2mL:0.25mL:4-8 μ L:8-12 μ L；The quality of the ammonium hydroxide is dense
Degree is 25%；The time of the ultrasonic disperse is 20-30min；
The first time is stirred to react, and temperature is 35 DEG C, time 5-10min；Described to be stirred to react for the second time, temperature is
65 DEG C, time 8-10h；The third time is stirred to react, and temperature is 65 DEG C, time 2-4h；The ethyl alcohol and deionized water
The volume ratio of ethyl alcohol and deionized water is 1:1 in mixed liquor.
Preferably, in step 3, the concentration of the amino functional up-conversion nano material solution is 5mg/mL；It is described double
The concentration of sulphur hydrogencarbonate aqueous solution is 0.1mg/mL, and the solvent of dithizone solution is the mixed liquor of ethyl alcohol and deionized water, wherein ethyl alcohol and
The volume ratio of deionized water is 9:1；The volume ratio of the amino functional up-conversion nano material solution and dithizone solution is
1:1.
Preferably, in step 4,0.01-1 μM of the concentration range of the cadmium-ion solution；The pH of the cadmium-ion solution is
8-10；The volume ratio of the cadmium-ion solution and specific detection system is 0.5:2；The fluorescence intensity of the measurement detection solution
Signal characteristic value: the fluorescence intensity level specifically under measurement 980nm excitation at 547nm and 758nm is denoted as I547With
I758, I547With I758Ratio (the I of fluorescence547/I758), for the fluorescence intensity signals characteristic value for detecting solution.
Preferably, in step 5, the amount ratio of the tea powder and concentrated nitric acid is 1.0g:15mL；The adjusting digestion solution pH
Specially 8-10 is adjusted to using 0.1 μM of sodium hydroxide and 0.1 μM of hydrochloric acid；The volume of the digestion solution and specific detection system
Than for 0.5:2.
Methanol A used in the present invention, methanol B are methanol, and alphabetical A, B are only difference nominally.
Compared with existing detection technique, beneficial effects of the present invention are as follows:
1. the present invention discloses a kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system, tool
Body prepares fluorogenic donor by the controllable self assembly of nanometer, constructs the cadmium ion detection architecture of stable state specificity, elimination background fluorescence,
Inexpensive, the highly sensitive and specific detection of Cadmium in Tea is realized in the influence of other ion interferences and millet paste color.
2. the specific detection system that the present invention constructs, the amino functional up-conversion nano material-of specific optimization design
Dithizone mixed system has strong fluorescence response to cadmium ion, can effectively eliminate background fluorescence and the interference of other ions,
There is specificity to the detection of cadmium.
3. the linear concentration range of the concentration of cadmium ions that the present invention establishes and fluorescence intensity signals characteristic value is 0.01-1 μM,
With wider linear detection range, detection limit LOD is 3.70nM, can satisfy quick, the highly sensitive detection of Cadmium in Tea, has
There is good versatility, it is higher than traditional technique in measuring accuracy and sensitivity.
Detailed description of the invention
Fig. 1 is the transmission electron microscope picture of amino functional up-conversion nano material prepared by embodiment 1.
Fig. 2 is the fluorescence signal figure for detecting solution in embodiment 1 under different concentration of cadmium ions.
Fig. 3 is cadmium content examination criteria curve in embodiment 1.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In technical solution be explicitly described, it is clear that described embodiments are some of the embodiments of the present invention, rather than all
Embodiment；Based on the embodiments of the present invention, those of ordinary skill in the art institute without making creative work
The every other embodiment obtained, shall fall within the protection scope of the present invention.
Embodiment 1:
The present invention discloses a kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system, specifically
Step are as follows:
Step 1, the preparation of up-conversion nano material: weigh six water yttrium chloride of 0.087g, six water ytterbium chloride of 0.047g,
Six water gadolinium chloride of six water holmium chloride of 0.005g and 0.066g goes to three mouthfuls of burnings of 250mL with 3mL methanol ultrasonic dissolution 5min
In bottle, add 4.5mL oleic acid and 10.5mL 1- octadecylene；Under the protection of argon gas, it is heated to 160 DEG C, magnetic agitation for the first time
30min is reacted, is cooled to room temperature；The methanol that ammonium fluoride containing 0.221g and 0.45g sodium hydroxide are added dropwise into coolant liquid is molten
Liquid 15mL, 50 DEG C of reaction 30min of first time water-bath, second of water-bath, 80 DEG C of reaction 40min wave the methanol in solution completely
Hair；Then, under the protection of argon gas, it is heated to 300 DEG C, magnetic agitation reaction 1h for the second time, is cooled to room temperature, is reacted
Product；Finally, being carried out with ethyl alcohol and methylene chloride (volume ratio 1:2) mixed solution to reaction product true at cleaning 3 times, 60 DEG C
Sky is dry, obtains up-conversion nano material.
The amino functional of up-conversion nano material: step 2 precisely weighs the upper conversion nano that 10mg step 1 obtains
6mL ethyl alcohol, ultrasonic disperse 25min is added in 100mL conical flask in material；Then by 2mL deionized water and 0.25mL 25%
Ammonium hydroxide sequentially add in up-conversion nano material solution, under 35 DEG C of water bath conditions, be stirred to react 8min for the first time；Then exist
Under 65 DEG C of water bath conditions, 6 μ L tetraethyl silicate resins are added dropwise, are stirred to react 9h for the second time；The 3- ammonia third of 10 μ L is added dropwise
Ethyl triethoxy silicane alkane, is stirred to react 3h for the third time, is cooled to room temperature, and obtains reaction product；Finally use ethyl alcohol and deionized water
Mixed liquor (volume ratio 1:1) to reaction product clean, vacuum drying, obtain amino functional up-conversion nano material (figure
1)。
Step 3, the building of specific detection system: the amino functional up-conversion nano material for taking step 2 to obtain is matched
It is set to the aqueous solution of 5mg/mL, and configures 0.1mg/mL dithizone solution (solvent is ethyl alcohol and deionized water, volume ratio 9:1),
Amino functional up-conversion nano material solution is mixed into (volume ratio 1:1) with dithizone solution, is obtained on amino functional
Conversion nano material-dithizone mixed system, as specific detection system.
Ethyl alcohol and the analysis of the ratio optimization of deionized water in dithizone solvent: dithizone is dissolved into different proportion respectively
In ethyl alcohol and deionization solvent, 0.5 μM of cadmium-ion solution of 0.5mL is added, successively acquires different proportion after hybrid reaction 1min
The visible light of ethyl alcohol and deionized water solvent.When the volume ratio of ethyl alcohol and deionized water is 9:1, dithizone visible light is inhaled
The range for receiving peak red shift is maximum, captures the sensitivity highest of cadmium ion.
The pH of detection architecture optimizes analysis: the cadmium-ion solution of different pH being added in dithizone solution, pH=3-6 is worked as
When, mixed solution has an absorption peak in 470nm, and as pH=7-10, mixed solution has one at 480nm and 610nm respectively
A absorption peak, after cadmium ion is added, only when red shift just occurs for the absorption peak of pH=8-10 solution, with up-conversion nano material
In the transmitting overlap of peaks of 500-600nm；Therefore, cadmium-ion solution pH=8-10 is the Optimal pH testing conditions of detection architecture,
In implementation process, the pH of cadmium-ion solution is 8.
In order to obtain the maximum specific detection system of fluorescence intensity, amino functional up-conversion nano material solution and double
The volume ratio of sulphur hydrogencarbonate aqueous solution is determining by detection signal optimization.Specifically, first preparing on the amino functional of 5mg/mL
Convert solution and 0.004,0.06,0.08,0.1,0.2,0.3, the dithizone solution of the various concentrations such as 0.4mg/mL；By 1mL
Amino functional up-conversion nano material solution is mixed with the dithizone solution of 1mL various concentration, and 0.5 μM of cadmium of 0.5mL is added
Solion, after reacting 1-2min, the fluorescence spectrum of acquisition testing solution；When the concentration of dithizone is 0.1mg/mL, fluorescence
Efficiency highest is quenched, i.e. 0.1mg/mL is the optium concentration of dithizone；5mg/mL amino functional up-conversion nano material is molten
Liquid mixes in equal volume with 0.1mg/mL dithizone solution, obtained amino functional up-conversion nano material-dithizone mixture
System, i.e. specific detection system have strong fluorescence response to cadmium ion, have high specificity and sensitive to the detection of cadmium
Property.
Step 4, the foundation of cadmium content examination criteria curve: respectively by the cadmium-ion solution (pH=of 0.5mL various concentration
8) it is added in the specific detection system that 2mL step 3 obtains, obtains detection solution, the fluorescence intensity letter of measurement detection solution
Number characteristic value Y establishes the relationship of concentration of cadmium ions x and fluorescence intensity signals characteristic value Y to get bent to cadmium content examination criteria
Line.Specifically, the cadmium-ion solution of the various concentrations such as 0.01,0.025,0.05,0.1,0.25,0.75 and 1 μM of configuration, takes
0.5mL cadmium-ion solution is mixed with the specific detection system that 2mL step 3 obtains, and obtains detection solution, measurement detection solution
Fluorescence signal under 980nm exciting light；Fig. 2 is the fluorescence signal of detection solution under the conditions of various concentration cadmium-ion solution, with
Concentration of cadmium ions increase, the up-conversion fluorescence intensity at 547nm constantly declines, and fluorescence intensity is constant at 650nm, 758nm,
Choose the ratio (I of fluorescence intensity at 547nm and 758nm547/I758) as the fluorescence intensity signals feature for reacting concentration of cadmium ions
Value Y constructs I547/I758With concentration of cadmium ions relationship, cadmium content examination criteria curve Y=-2.854x+6.025 is obtained, determines system
Number R2=0.9905, detection limit LOD is 3.70nM, and the range of linearity is 0.01-1 μM.
The detection of Cadmium in Tea content: tealeaves sample is smashed the sieving of 40 mesh, obtains tea powder by step 5；Then 1.0g is taken
Tea powder and the mixing of 15mL concentrated nitric acid carry out micro-wave digestion, and 120 DEG C of reaction 5min in Hyperfrequency waves eliminating stove are heated to 160 DEG C of continuation
10min is reacted, then temperature is raised to 180 DEG C of reaction 10min, then room temperature is cooling；Resolution liquid is then placed into 150 DEG C of oil baths
In pot, make the acid volatilization completely in its solution, then offset solution liquid with filter and be filtered, using 0.1 μM of sodium hydroxide and
0.1 μM of hydrochloric acid adjusts digestion solution pH to 8, and (being diluted with the sodium hydroxide solution that pH is 8, determine concentration) takes the digestion solution of 0.5mL
It is added in amino functional up-conversion nano material-dithizone mixed system of 2mL, obtains detection solution, measurement detection is molten
Fluorescence intensity level of the liquid under 980nm laser excitation at 547nm, 758nm, obtains I547/I758Fluorescence intensity signals characteristic value is led to
Constructed cadmium content examination criteria curve is crossed, the cadmium content of tealeaves sample is calculated.
Embodiment 2:
The present invention discloses a kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system, specifically
Step are as follows:
Step 1, the preparation of up-conversion nano material: weigh six water yttrium chloride of 0.087g, six water ytterbium chloride of 0.047g,
Six water gadolinium chloride of six water holmium chloride of 0.005g and 0.066g goes to three mouthfuls of burnings of 250mL with 3mL methanol ultrasonic dissolution 10min
In bottle, add 4.5mL oleic acid and 10.5mL 1- octadecylene；Under the protection of argon gas, it is heated to 150 DEG C, magnetic agitation for the first time
30min is reacted, is cooled to room temperature；The methanol that ammonium fluoride containing 0.221g and 0.45g sodium hydroxide are added dropwise into coolant liquid is molten
Liquid 15mL, 45 DEG C of reaction 30min of first time water-bath, second of water-bath, 85 DEG C of reaction 40min wave the methanol in solution completely
Hair；Then, under the protection of argon gas, it is heated to 310 DEG C, magnetic agitation reaction 1h for the second time, is cooled to room temperature, is reacted
Product；Finally, being carried out with ethyl alcohol and methylene chloride (volume ratio 1:2) mixed solution to reaction product true at cleaning 3 times, 60 DEG C
Sky is dry, obtains up-conversion nano material.
The amino functional of up-conversion nano material: step 2 precisely weighs the upper conversion nano that 10mg step 1 obtains
6mL ethyl alcohol, ultrasonic disperse 20min is added in 100mL conical flask in material；Then by 2mL deionized water and 0.25mL 25%
Ammonium hydroxide sequentially add in up-conversion nano material solution, under 35 DEG C of water bath conditions, be stirred to react 5min for the first time；Then exist
Under 65 DEG C of water bath conditions, 4 μ L tetraethyl silicate resins are added dropwise, are stirred to react 8h for the second time；The 3- aminopropyl of 8 μ L is added dropwise
Triethoxysilane is stirred to react 2h for the third time, is cooled to room temperature, and obtains reaction product；Finally with ethyl alcohol and deionized water
Mixed liquor (volume ratio 1:1) cleans reaction product, and vacuum drying obtains amino functional up-conversion nano material.
Step 3, the building of specific detection system: the amino functional up-conversion nano material for taking step 2 to obtain is matched
It is set to the aqueous solution of 5mg/mL, and configures 0.1mg/mL dithizone solution (solvent is ethyl alcohol and deionized water, volume ratio 9:1),
Amino functional up-conversion nano material solution is mixed into (volume ratio 1:1) with dithizone solution, is obtained on amino functional
Conversion nano material-dithizone mixed system, as specific detection system.
Step 4, the foundation of cadmium content examination criteria curve: respectively by the cadmium-ion solution (pH=of 0.5mL various concentration
9) it is added in the specific detection system that 2mL step 3 obtains, obtains detection solution, the fluorescence intensity letter of measurement detection solution
Number characteristic value Y establishes the relationship of concentration of cadmium ions x and fluorescence intensity signals characteristic value Y to get bent to cadmium content examination criteria
Line；Specifically, the cadmium-ion solution of the various concentrations such as 0.01,0.025,0.05,0.1,0.25,0.75 and 1 μM of configuration, takes
0.5mL cadmium-ion solution is mixed with the specific detection system that 2mL step 3 obtains, and obtains detection solution, measurement detection solution
Fluorescence intensity level (the I at 547nm and 758nm under 980nm exciting light547And I758), with I547With I758Ratio (I547/I758) make
For the fluorescence intensity signals characteristic value Y for reacting concentration of cadmium ions, establish concentration of cadmium ions x's and fluorescence intensity signals characteristic value Y
Relationship to get arrive cadmium content examination criteria curve Y=-2.851x+6.020, coefficient of determination R2=0.9895, detection limit LOD are
3.73nM, the range of linearity are 0.01-1 μM.
The detection of Cadmium in Tea content: tealeaves sample is smashed the sieving of 40 mesh, obtains tea powder by step 5；Then 1.0g is taken
Tea powder and the mixing of 15mL concentrated nitric acid carry out micro-wave digestion, and 120 DEG C of reaction 5min in Hyperfrequency waves eliminating stove are heated to 160 DEG C of continuation
10min is reacted, then temperature is raised to 180 DEG C of reaction 10min, then room temperature is cooling；Resolution liquid is then placed into 140 DEG C of oil baths
In pot, make the acid volatilization completely in its solution, then offset solution liquid with filter and be filtered, using 0.1 μM of sodium hydroxide and
0.1 μM of hydrochloric acid adjusts digestion solution pH to 9 (being diluted with the sodium hydroxide solution that pH is 9, determine concentration), takes the digestion solution of 0.5mL
It is added in amino functional up-conversion nano material-dithizone mixed system of 2mL, obtains detection solution, measurement detection is molten
Fluorescence intensity level of the liquid under 980nm laser excitation at 547nm, 758nm, obtains I547/I758Fluorescence intensity signals characteristic value is led to
Constructed cadmium content examination criteria curve is crossed, the cadmium content of tealeaves sample is calculated.
Embodiment 3:
The present invention discloses a kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system, specifically
Step are as follows:
Step 1, the preparation of up-conversion nano material: weigh six water yttrium chloride of 0.087g, six water ytterbium chloride of 0.047g,
Six water gadolinium chloride of six water holmium chloride of 0.005g and 0.066g goes to three mouthfuls of burnings of 250mL with 3mL methanol ultrasonic dissolution 8min
In bottle, add 4.5mL oleic acid and 10.5mL 1- octadecylene；Under the protection of argon gas, it is heated to 170 DEG C, magnetic agitation for the first time
30min is reacted, is cooled to room temperature；The methanol that ammonium fluoride containing 0.221g and 0.45g sodium hydroxide are added dropwise into coolant liquid is molten
Liquid 15mL, 55 DEG C of reaction 30min of first time water-bath, second of water-bath, 75 DEG C of reaction 40min wave the methanol in solution completely
Hair；Then, under the protection of argon gas, it is heated to 290 DEG C, magnetic agitation reaction 1h for the second time, is cooled to room temperature, is reacted
Product；Finally, being carried out with ethyl alcohol and methylene chloride (volume ratio 1:2) mixed solution to reaction product true at cleaning 3 times, 60 DEG C
Sky is dry, obtains up-conversion nano material.
The amino functional of up-conversion nano material: step 2 precisely weighs the upper conversion nano that 10mg step 1 obtains
6mL ethyl alcohol, ultrasonic disperse 30min is added in 100mL conical flask in material；Then by 2mL deionized water and 0.25mL 25%
Ammonium hydroxide sequentially add in up-conversion nano material solution, under 35 DEG C of water bath conditions, be stirred to react 10min for the first time；Then
Under 65 DEG C of water bath conditions, 8 μ L tetraethyl silicate resins are added dropwise, are stirred to react 10h for the second time；The 3- ammonia of 12 μ L is added dropwise
Propyl-triethoxysilicane is stirred to react 4h for the third time, is cooled to room temperature, and obtains reaction product；Finally use ethyl alcohol and deionization
The mixed liquor (volume ratio 1:1) of water cleans reaction product, and vacuum drying obtains amino functional up-conversion nano material.
Step 3, the building of specific detection system: the amino functional up-conversion nano material for taking step 2 to obtain is matched
It is set to the aqueous solution of 5mg/mL, and configures 0.1mg/mL dithizone solution (solvent is ethyl alcohol and deionized water, volume ratio 9:1),
Amino functional up-conversion nano material solution is mixed into (volume ratio 1:1) with dithizone solution, is obtained on amino functional
Conversion nano material-dithizone mixed system, as specific detection system.
Step 4, the foundation of cadmium content examination criteria curve: respectively by the cadmium-ion solution (pH=of 0.5mL various concentration
10) it is added in the specific detection system that 2mL step 3 obtains, obtains detection solution, the fluorescence intensity of measurement detection solution
Signal characteristic value Y establishes the relationship of concentration of cadmium ions x and fluorescence intensity signals characteristic value Y to get bent to cadmium content examination criteria
Line.Specifically, the cadmium-ion solution of the various concentrations such as 0.01,0.025,0.05,0.1,0.25,0.75 and 1 μM of configuration, takes
0.5mL cadmium-ion solution is mixed with the specific detection system that 2mL step 3 obtains, and obtains detection solution, measurement detection solution
Fluorescence intensity level (the I at 547nm and 758nm under 980nm exciting light547And I758), with I547With I758Ratio (I547/I758) make
For the fluorescence intensity signals characteristic value Y for reacting concentration of cadmium ions, establish concentration of cadmium ions x's and fluorescence intensity signals characteristic value Y
Relationship to get arrive cadmium content examination criteria curve Y=-2.872x+6.019, coefficient of determination R2=0.9801, detection limit LOD are
3.72nM, the range of linearity are 0.01-1 μM.
The detection of Cadmium in Tea content: tealeaves sample is smashed the sieving of 40 mesh, obtains tea powder by step 5；Then 1.0g is taken
Tea powder and the mixing of 15mL concentrated nitric acid carry out micro-wave digestion, and 120 DEG C of reaction 5min in Hyperfrequency waves eliminating stove are heated to 160 DEG C of continuation
10min is reacted, then temperature is raised to 180 DEG C of reaction 10min, then room temperature is cooling；Resolution liquid is then placed into 160 DEG C of oil baths
In pot, make the acid volatilization completely in its solution, then offset solution liquid with filter and be filtered, using 0.1 μM of sodium hydroxide and
0.1 μM of hydrochloric acid adjusts digestion solution pH to 10 (being diluted with the sodium hydroxide solution that pH is 9, determine concentration), takes the digestion solution of 0.5mL
It is added in amino functional up-conversion nano material-dithizone mixed system of 2mL, obtains detection solution, measurement detection is molten
Fluorescence intensity level of the liquid under 980nm laser excitation at 547nm, 758nm, obtains I547/I758Fluorescence intensity signals characteristic value is led to
Constructed cadmium content examination criteria curve is crossed, the cadmium content of tealeaves sample is calculated.
Detection: to 4 tealeaves standard samples, using 1 the method for the embodiment of the present invention and step, to Cadmium in Tea content
It is measured, shown in measurement result table 1, it can be seen that the testing result of the method for the present invention and standard atomic absorption spectrometry is without aobvious
Sex differernce is write, shows that the method for the present invention can detect Cadmium in Tea content in high precision.
The result (unit, μM) of cadmium content in 1 the method for the present invention of table and standard method detection tealeaves standard sample
T=1.00 < t0.05(3)=3.182, P > 0.05
When constructed detection method is used for the detection of other metal ion titers, ion such as K+、Na+、Mn2+、Al3 +、Pb2+、Mg2+、Hg2+、Fe2+、Cu2+、Ba2+It will not cause the variation of system fluorescence signal Deng 100 times, be only added in system
The fluorescence intensity of system can just change significantly when cadmium-ion solution.And to special in the presence of the upper ion
Property detection architecture in the anti-interference experiment of cadmium is added, cadmium ion, which is added, can all cause the significant change of fluorescence intensity, as a result table
Bright, constructed specific detection system is hardly influenced by other coexisting ions when detecting cadmium ion, is shown constructed
Detection method there is high specific, highly selective to cadmium ion.
Illustrate: above embodiments are only to illustrate the present invention and not limit the technical scheme described by the invention；Therefore,
Although this specification is referring to above-mentioned each embodiment, the present invention has been described in detail, the common skill of this field
Art personnel should be appreciated that and still can modify to the present invention or equivalent replacement；And all do not depart from spirit of the invention and
The technical solution and its improvement of range, should all cover in scope of the presently claimed invention.
Claims (8)
1. a kind of Cadmium in Tea detection method of content based on upper conversion and dithizone specificity system, which is characterized in that including
Following steps:
Step 1: up-conversion nano material is prepared；
Step 2: the up-conversion nano material that step 1 is obtained is added in ethyl alcohol, ultrasonic disperse, and deionized water and ammonia is added
Water be stirred to react for the first time；Tetraethyl silicate resin is added, is stirred to react for the second time；Three ethoxy of 3- aminopropyl is added
Base silane carries out third time and is stirred to react, is cooled to room temperature, obtains reaction product；With the mixed liquor pair of ethyl alcohol and deionized water
Reaction product cleaning, vacuum drying obtain amino functional up-conversion nano material；
The building of specific detection system: step 3 the amino functional up-conversion nano material that step 2 obtains is dissolved in
In ionized water, amino functional up-conversion nano material solution is obtained, is then mixed with dithizone solution, obtains amino functional
Up-conversion nano material-dithizone mixed system, i.e. specific detection system；
The foundation of cadmium content examination criteria curve: the cadmium-ion solution of various concentration is added to step 3 respectively and obtained by step 4
To specific detection system in, obtain detection solution, measurement detection solution fluorescence intensity signals characteristic value, it is dense with cadmium ion
Degree is abscissa, and fluorescence intensity signals characteristic value is ordinate, establishes cadmium content examination criteria curve；
The detection of Cadmium in Tea content: step 5 tealeaves sample is smashed and is sieved, tea powder is obtained；Then by tea powder and concentrated nitric acid
Mixing carries out micro-wave digestion, and room temperature is cooling；So that acid volatilization completely, filtering in digestion solution is adjusted digestion solution pH using oil bath, is added
In the specific detection system obtained to step 3, detection solution is obtained, measurement detects the fluorescence intensity signals characteristic value of solution,
The cadmium content examination criteria curve that step 4 obtains is substituted into, cadmium content in tealeaves sample is calculated.
2. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that up-conversion nano material described in step 2, ethyl alcohol, deionized water, ammonium hydroxide, tetraethyl silicate resin and 3-
The amount ratio of aminopropyl triethoxysilane is 10mg:6mL:2mL:0.25mL:4-8 μ L:8-12 μ L；The quality of the ammonium hydroxide is dense
Degree is 25%；The time of the ultrasonic disperse is 20-30min.
3. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that in step 2, the first time is stirred to react, and temperature is 35 DEG C, time 5-10min；Described second
It is stirred to react, temperature is 65 DEG C, time 8-10h；The third time is stirred to react, and temperature is 65 DEG C, time 2-4h；It is described
The volume ratio of ethyl alcohol and deionized water is 1:1 in ethyl alcohol and deionized water mixed liquor.
4. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that in step 3, the concentration of the amino functional up-conversion nano material solution is 5mg/mL；It is described double
The concentration of sulphur hydrogencarbonate aqueous solution is 0.1mg/mL, and the solvent of dithizone solution is the mixed liquor of ethyl alcohol and deionized water, wherein ethyl alcohol and
The volume ratio of deionized water is 9:1；The volume ratio of the amino functional up-conversion nano material solution and dithizone solution is
1:1.
5. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that in step 4,0.01-1 μM of the concentration range of the cadmium-ion solution；The pH of the cadmium-ion solution is
8-10；The volume ratio of the cadmium-ion solution and specific detection system is 0.5:2.
6. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that in step 4, the fluorescence intensity signals characteristic value of the measurement detection solution: specifically measurement 980nm swashs
Shine the fluorescence intensity level excited at lower 547nm and 758nm, is denoted as I547And I758；I547With I758Ratio, for detection solution
Fluorescence intensity signals characteristic value.
7. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that in step 5, the amount ratio of the tea powder and concentrated nitric acid is 1.0g:15mL.
8. a kind of Cadmium in Tea content detection side based on upper conversion and dithizone specificity system according to claim 1
Method, which is characterized in that in step 5, the adjusting digestion solution pH is to be adjusted to 8- using 0.1 μM of sodium hydroxide and 0.1 μM of hydrochloric acid
10；The volume ratio of the digestion solution and specific detection system is 0.5:2.
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