CN113959994A - Method for detecting residual metal ions in quantum dots - Google Patents
Method for detecting residual metal ions in quantum dots Download PDFInfo
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- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
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- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
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Abstract
The invention discloses a method for detecting residual metal ions in quantum dots, which comprises the following steps: determining the concentration and response value R of the metal ions according to the fluorescence intensity before and after the functionalized graphene quantum dot solution is added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2The corresponding relationship of (a); according to the determined metal ion concentration and response value R2Determining the concentration of residual metal ions in the quantum dot solution to be detected according to the corresponding relation. The method can efficiently and quickly detect whether the quantum dots contain residual metal ions or not, and can quickly calculate the concentration of the residual metal ions according to a linear equation so as to judge that the metal ions in the synthesized quantum dots are completely cleaned.
Description
Technical Field
The invention relates to the technical field of purity detection, in particular to a method for detecting residual metal ions in quantum dots.
Background
The functionalized graphene quantum dots can be used as multifunctional fluorescent probes and general fluorescent labeling platforms, and are always in the centers of fields such as material science, biological imaging and analytical chemistry since the discovery. This is largely due to the good photostability and biocompatibility of the functionalized graphene quantum dots. Most of the functionalized graphene quantum dots have oxygen-rich surface functional groups, so that subsequent further modification is very convenient. Besides the unique fluorescence characteristic, the graphene quantum dot has wide prospects in photocatalysis and biological enzyme simulation. The above properties have been successfully applied in electrochemical and colorimetric sensors. Wherein the most difficult and expensive characteristic of functionalized graphene quantum dots is controllable optical properties. In other words: the fluorescence of the functionalized graphene quantum dots is jointly regulated and controlled by a plurality of characteristic indexes and a solution environment, such as: quantum dot size, edge modification, functional groups, surface potential and passivation, solution pH, and solution polarity, among others. The functionalized graphene quantum dots are the most potential candidate materials for the development of the current ratio type fluorescent probe, and have wide prospects in the fields of chemical sensors and biological imaging.
Ratiometric fluorescent probes have received much attention in recent years. This is attributed to the fact that the ratio-type fluorescent probe can greatly reduce the influence of the excitation light intensity, concentration, solution environment and other conditions on the performance of the fluorescent probe. The conventional ratio-type fluorescent probe requires two luminescent materials with different emission colors/wavelengths, which greatly limits the construction of the ratio-type fluorescent probe. In addition, the fluorescence of the functionalized graphene quantum dots can be quenched by a variety of metal ions, such as mercury ions, silver ions, copper ions and iron ions, especially in the case of high metal ion concentration. The fluorescence quenching phenomenon of the metal ions on the functionalized graphene quantum dots is repeatedly discovered, and a plurality of simple metal ion probes are designed according to the repeated discovery. But such methods also apparently lack sufficient ion selectivity.
In view of this, there is an urgent need to further expand the strategy of ratiometric fluorescence, especially to construct novel ratiometric fluorescent probes with a single emission wavelength. The construction of a novel ratio-type fluorescent probe with a single emission wavelength will certainly expand the application range of the ratio sensing probe.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a method for detecting residual metal ions in quantum dots, aiming to solve the problem that the construction of the prior ratiometric fluorescent probe requires two luminescent materials emitting color/wavelength.
The technical scheme of the invention is as follows:
a method for detecting residual metal ions in quantum dots, comprising the steps of:
determining the concentration and response value R of the metal ions according to the fluorescence intensity before and after the functionalized graphene quantum dot solution is added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2The corresponding relationship of (a);
according to the determined metal ion concentration and response value R2Determining the concentration of residual metal ions in the quantum dot solution to be detected according to the corresponding relation.
Has the advantages that: the invention provides a method for constructing a single-ratio type fluorescent probe based on a functionalized graphene quantum dot fluorescent material, which constructs a method for detecting residual metal ions in quantum dots by using a single-emission-wavelength ratio type fluorescent probe under the assistance of ultraviolet radiation through utilizing the self-catalyzed light-controlled fluorescence property of the functionalized graphene quantum dots. The method provided by the invention can efficiently and quickly detect whether the quantum dots contain residual metal ions or not, and can determine the concentration and the response value R of the metal ions according to the determined concentration and the response value R of the metal ions2The corresponding relation (such as linear relation) of the above steps is quickly calculated to obtain the concentration of the residual metal ions, so that the metal ions in the synthesized quantum dots are judged to be completely cleaned.
Drawings
Fig. 1 is a schematic flow chart of a method for detecting residual metal ions in quantum dots according to an embodiment of the present invention.
FIG. 2 is a zinc ion standard curve equation in example 1 according to the present invention.
Detailed Description
The invention provides a method for detecting residual metal ions in quantum dots, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a method for detecting residual metal ions in quantum dots, which comprises the following steps of:
s10, determining the concentration and response value R of the metal ions according to the fluorescence intensity before and after the functionalized graphene quantum dot solution is added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2The corresponding relationship of (a);
s20, according to the determined metal ion concentration and response value R2Determining the concentration of residual metal ions in the quantum dot solution to be detected according to the corresponding relation.
It should be noted that, in the quantum dot according to the embodiment of the present invention, the residual metal ions refer to that the quantum dot is synthesized by using a raw material containing metal ions such as metal cadmium ions or metal zinc ions, so that a small amount of metal cadmium ions or metal zinc ions mostly remain in the synthesized quantum dot. In order to detect whether the quantum dots contain residual metal ions and the concentration of the residual metal ions, the embodiment of the invention provides a method for constructing a single-ratio type fluorescent probe based on a functionalized graphene quantum dot fluorescent material. The method provided by the invention can efficiently and quickly detect whether the quantum dots contain residual metal ions or not, and can determine the concentration and the response value R of the metal ions according to the determined concentration and the response value R of the metal ions2The corresponding relation (such as linear relation) of the above steps is quickly calculated to obtain the concentration of the residual metal ions, so that the metal ions in the synthesized quantum dots are judged to be completely cleaned.
In the embodiment of the invention, under the condition of no additional metal ions, the fluorescence intensity of the functionalized graphene quantum dots can be obviously reduced through ultraviolet irradiation. This process is called photobleaching. Under the condition of externally increasing high-concentration metal ions, the fluorescence intensity of the functionalized graphene quantum dots is also remarkably reduced through ultraviolet irradiation. When residual metal ions (such as a small amount of spacers, zinc ions and the like) exist in the quantum dots, the spacers, the zinc ions and the like can prevent the photodamage process of ultraviolet light to the functionalized graphene quantum dots, so the photobleaching process of the functionalized graphene quantum dots is greatly inhibited, and the fluorescence intensity after ultraviolet irradiation is enhanced. In other words, the functionalized graphene quantum dots exhibit a completely opposite fluorescent response to residual metal ions in the quantum dots with/without ultraviolet illumination. Therefore, the ratio of the fluorescence intensity change under the condition of ultraviolet illumination to the fluorescence intensity change under the condition of no ultraviolet illumination is taken as a characteristic value of fluorescence response, and a ratio type fluorescence sensing system is designed to detect whether metal ions which are not completely cleaned are remained after the quantum dots are cleaned.
The functionalized graphene quantum dots generate singlet oxygen under the irradiation of ultraviolet light (1O2) The singlet oxygen has strong oxidizing ability, and can generate oxidation reaction with C ═ C double bonds on the functionalized graphene quantum dots to break the double bonds. The aromatic conjugated structure of the graphene quantum dot can be damaged by the reaction, so that the fluorescence of the functionalized graphene quantum dot solution is weakened. And in the second subgroup element ion (M)x+E.g. Cd2+、Zn2+Etc.) can react with the highly reactive singlet oxygen to generate another reactive oxygen species (superoxide radical O)2 ·-) Superoxide radical O2 ·-Can react with water molecules in the air, thereby avoiding the oxidation reaction between singlet oxygen and the graphene quantum dots and further avoiding the fluorescence attenuation of the functionalized graphene quantum dots. The specific reaction formula is shown as follows:
in the embodiment of the present invention, whether the quantum dot solution contains residual cadmium ions or zinc ions or not is determined by determining the change in fluorescence intensity of the functionalized graphene quantum dots in the presence or absence of ultraviolet light or in the presence or absence of metal ions. And if the single condition is changed to judge the change of the fluorescence intensity of the graphene quantum dots, interference of other factors may exist. In addition, the embodiment of the invention utilizes the characteristic that residual metal ions such as cadmium ions or zinc ions in the quantum dots can prevent ultraviolet light from damaging the graphene quantum dots, and other metal ions do not have the characteristic, and designs a ratio type fluorescence sensing system to detect whether metal cadmium ions or zinc ions which are not completely cleaned and the like are still remained after the quantum dots are cleaned. Therefore, the method provided by the embodiment of the invention has the advantages of strong specificity, accuracy and reliability.
When a small amount of metal cadmium ions and metal zinc ions remain in the quantum dots at the same time, the detection can be performed by the following method: firstly, the functionalized graphene quantum dot solution is divided into two parts. Adding a proper amount of zinc ion complexing and masking agent into one part of the solution to completely mask zinc ions so as to retain cadmium ions, and detecting the quantum dot solution to be detected only containing cadmium ions, wherein the zinc ion complexing and masking agent comprises but is not limited to at least one of ethylene diamine tetraacetic acid, 1, 10-phenanthroline, dimercaptopropanol, sodium dimercaptopropane sulfonate, mercaptoethylamine and thioglycolic acid; and adding a proper amount of cadmium ion complexing and masking agent into the other part to completely mask cadmium ions so as to retain zinc ions, and detecting the solution of the quantum dots to be detected only containing the zinc ions, wherein the cadmium ion complexing and masking agent comprises but is not limited to at least one of phenanthroline, 4-nitrobenzene and 1- (4-nitrophenyl) -3- (5-bromopyridine) -triazene.
In step S10, in an embodiment, the fluorescence intensities before and after the functionalized graphene quantum dot solution is added to the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation are measured by the following method:
preparing a plurality of groups of metal ion standard solutions with different concentrations, mixing each group of metal ion standard solutions with the functionalized graphene quantum dot solution respectively, measuring the fluorescence intensity of each group of mixed solutions after ultraviolet irradiation, and measuring the fluorescence intensity of each group of mixed solutions without ultraviolet irradiation;
and (3) taking the functionalized graphene quantum dot solution, measuring the fluorescence intensity of the solution after ultraviolet irradiation, and measuring the fluorescence intensity of the solution without ultraviolet irradiation.
In the embodiment of the invention, each group of metal ion standard solution is mixed with the functionalized graphene quantum dot solution to obtain each group of mixed solution, and the fluorescence intensity of each mixed solution under the condition of ultraviolet illumination or non-ultraviolet illumination is measured. The fluorescence intensity of each group of mixed solution under the condition of no ultraviolet irradiation is measured simultaneously, namely, after each group of metal ion standard solution is mixed with the functionalized graphene quantum dot solution, the mixed solution obtained by mixing is not subjected to ultraviolet irradiation, and the fluorescence intensity of each group of mixed solution is directly measured.
In one embodiment, the preparing the sets of metal ion standard solutions with different concentrations may be preparing metal ion standard solutions with concentration values of 10, 20, 40, and 100ug/mL, respectively.
In one embodiment, the metal ions include one or more of cadmium ions, zinc ions, and the like, but are not limited thereto.
In one embodiment, the ultraviolet radiation may have an intensity of from 10 to 30 watts.
In one embodiment, the illumination time of the ultraviolet irradiation may be 10 to 30 minutes.
In one embodiment, the functionalized graphene quantum dots include one or more of dot-defect functionalized graphene quantum dots, single-hole-defect functionalized graphene quantum dots, multiple-hole-defect functionalized graphene quantum dots, line-defect functionalized graphene quantum dots, and out-of-plane carbon atom-introduced-defect functionalized graphene quantum dots, but are not limited thereto.
In the embodiment of the present invention, the functionalized graphene quantum dot means that the graphene quantum dot imparts a new property to the graphene quantum dot by introducing a specific functional group, that is, the graphene quantum dot has a corresponding function. In one embodiment, the functionalized graphene quantum dots have one or more oxygen-containing functional groups such as a carboxyl group, an alcoholic hydroxyl group, a phenolic hydroxyl group, an ether bond, an aldehyde group, a ketone group, a carbonyl group, an ester group, an acid anhydride, and a nitro group, but are not limited thereto. Since graphene is lamellar and has a large specific surface area at the edge, it is easily oxidized and modified with the oxygen-containing functional group.
In one embodiment, the concentration of the functionalized graphene quantum dot solution is 10-200 mg/ml.
In step S10, in an embodiment, the metal ion concentration and the response value R are determined according to fluorescence intensities before and after the functionalized graphene quantum dot solution is added to the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2The step of corresponding relationship of (2), comprising:
calculating a response value R through a custom formula according to fluorescence intensities before and after the functionalized graphene quantum dot solution is added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2；
According to the response value R2Obtaining the metal ion concentration and the response value R according to the corresponding metal ion concentration2The corresponding relationship of (a);
the custom formula is shown as follows:
wherein, F1 UVThe fluorescence intensity of the functionalized graphene quantum dots added with metal ions after ultraviolet irradiation is F0 UVIs the fluorescence intensity of the functionalized graphene quantum dots after ultraviolet irradiation without adding metal ions, F1 NONEIs the fluorescence intensity of the functionalized graphene quantum dots after being added with metal ions without ultraviolet irradiation, F0 NONEThe fluorescence intensity of the functionalized graphene quantum dots without metal ions and ultraviolet irradiation is shown, R represents a response value, and the higher R is, the higher the response degree is, the more obvious the reaction phenomenon or result is.
In the embodiment of the invention, the custom male is utilizedThe formula obtains the concentration and response value (R) of metal ions2) And obtaining a standard curve equation of the metal ions according to the corresponding relation, so as to measure the concentration of the residual metal ions in the unknown quantum dots.
In step S20, in one embodiment, the determining step is based on the determined metal ion concentration and the response value R2The step of determining the concentration of the residual metal ions in the quantum dot solution to be detected according to the corresponding relationship comprises the following steps:
s21, mixing the quantum dot solution to be measured with the functionalized graphene quantum dot solution, measuring the fluorescence intensity of the mixed solution after ultraviolet irradiation, and simultaneously measuring the fluorescence intensity of the mixed solution without ultraviolet irradiation;
s22, taking the functionalized graphene quantum dot solution, measuring the fluorescence intensity of the solution after ultraviolet irradiation, and measuring the fluorescence intensity of the solution without ultraviolet irradiation;
s23, according to the determined metal ion concentration and response value R2And calculating the concentration of residual metal ions in the quantum dot solution to be measured according to the corresponding relation, the fluorescence intensity under ultraviolet irradiation and the fluorescence intensity without ultraviolet irradiation obtained by measurement.
The functionalized graphene quantum dot solution in step S21 has the same concentration and the same amount as the functionalized graphene quantum dot solution in step S10.
The invention is further illustrated by the following specific examples.
Example 1
1. Functional graphene quantum dots with carboxyl groups and point defects modified on the edges are prepared into a functional graphene quantum dot solution of 20mg/mL, and the solvent adopted for preparation is an aqueous solvent.
2. Preparing a series of zinc metal ion standard solutions with concentration values of 10, 20, 40 and 100ug/mL respectively, adding the zinc metal ion standard solutions into five parts of the functionalized graphene quantum dot solutions obtained in the step 1, and measuring F1 NONEThe fluorescence values are 301, 286, 254 and 189, respectively.
3. Preparing a series of zinc metal ion standards with concentration values of 10, 20, 40 and 100ug/mL respectivelyAdding the solution into five parts of the functionalized graphene quantum dot solution obtained in the step 1, respectively, irradiating for 10 minutes by using an ultraviolet light source with the power of 10 watts, and measuring the fluorescence intensity value of the functionalized graphene quantum dot solution after 10 minutes, wherein F is the fluorescence intensity value of the functionalized graphene quantum dot solution1 UV653, 1241, 2541, 5100, respectively.
4. Taking five parts of the functionalized graphene quantum dot solution prepared in the step 1, adding no zinc metal ion standard solution, irradiating for 10 minutes by using an ultraviolet light source with the power of 10 watts, measuring the fluorescence intensity value of the functionalized graphene quantum dot solution after 10 minutes, and measuring F0 UV345, 346, 339, 325 respectively.
5. Taking five parts of the functionalized graphene quantum dot solution prepared in the step 1, adding no zinc metal ion standard solution, and measuring the fluorescence intensity value of the functionalized graphene quantum dot solution without ultraviolet irradiation, wherein F is the fluorescence intensity value0 NONE635, 628, 625, 630 respectively.
6. Calculating a zinc ion standard curve equation by a self-defined formula, wherein Y is 0.10968X-0.65758, X is the concentration of the metal ions, and Y is R2As shown in fig. 2.
Example 2
1. The functionalized graphene quantum dots with hydroxyl groups modified at the edges and linear defects are prepared into a 90mg/mL functionalized graphene quantum dot solution, and the solvent adopted for preparation is an aqueous solvent.
2. Preparing a series of cadmium metal ion standard solutions with concentration values of 10, 20, 40 and 100ug/mL, respectively adding the cadmium metal ion standard solutions into five parts of the functionalized graphene quantum dot solutions obtained in the step 1, and measuring F1 NONEThe fluorescence values are 299, 274, 248 and 194, respectively.
3. Preparing a series of cadmium metal ion standard solutions with concentration values of 10, 20, 40 and 100ug/mL, respectively adding the cadmium metal ion standard solutions into five parts of the functionalized graphene quantum dot solutions obtained in the step 1, irradiating the solutions for 10 minutes by using an ultraviolet light source with the power of 20 watts, measuring the fluorescence intensity value of the functionalized graphene quantum dot solutions after 10 minutes, and measuring F1 UV451, 865, 2198, 4865, respectively.
4. Taking five parts of the functionalized graphene quantum dot solution prepared in the step 1, irradiating the five parts of the functionalized graphene quantum dot solution for 10 minutes by using an ultraviolet light source with the power of 20 watts without adding a cadmium metal ion standard solution, measuring the fluorescence intensity value of the functionalized graphene quantum dot solution after 10 minutes, and measuring F0 UV213, 216, 239, 221 respectively.
5. Taking five parts of the functionalized graphene quantum dot solution prepared in the step 1, adding no cadmium metal ion standard solution, and measuring the fluorescence intensity value of the functionalized graphene quantum dot solution without ultraviolet irradiation, wherein F is the fluorescence intensity value0 NONE735, 728, 725, 730 respectively.
6. And calculating by a custom formula to obtain a cadmium ion standard curve equation, wherein Y is 0.21675 x-0.79532.
Example 3
1. Functional graphene quantum dots with aldehyde groups modified at the edges and single-hole defects are prepared into a 50mg/mL functional graphene quantum dot solution, and the solvent adopted for preparation is an aqueous solvent.
2. Preparing a series of zinc metal ion standard solutions with concentration values of 10, 20, 40 and 100ug/mL respectively, adding the zinc metal ion standard solutions into five parts of the functionalized graphene quantum dot solutions obtained in the step 1, and measuring F1 NONEThe fluorescence values are 401, 376, 298 and 180 respectively.
3. Preparing a series of zinc metal ion standard solutions with concentration values of 10, 20, 40 and 100ug/mL, respectively adding the zinc metal ion standard solutions into five parts of the functionalized graphene quantum dot solutions obtained in the step 1, irradiating the solutions for 10 minutes by using an ultraviolet light source with power of 30 watts, and measuring the fluorescence intensity value of the functionalized graphene quantum dot solutions after 10 minutes, wherein F is the fluorescence intensity value of the functionalized graphene quantum dot solutions1 UV753, 1451, 2641, 5340, respectively.
4. Taking five parts of the functionalized graphene quantum dot solution prepared in the step 1, adding no zinc metal ion standard solution, irradiating for 10 minutes by using an ultraviolet light source with the power of 30 watts, and measuring the fluorescence intensity value of the functionalized graphene quantum dot solution after 10 minutes, wherein F is the fluorescence intensity value of the functionalized graphene quantum dot solution0 UV313, 316, 339, 321, respectively.
5. Taking another five partsMeasuring the fluorescence intensity value F of the functionalized graphene quantum dot solution prepared in the step 1 without adding a zinc metal ion standard solution and carrying out ultraviolet irradiation0 NONE535, 528, 525, 530, respectively.
6. And calculating a zinc metal standard curve equation by a self-defined formula, wherein Y is 0.20432 x-0.4543.
In summary, the embodiment of the invention provides a method for constructing a single ratiometric fluorescent probe based on a functionalized graphene quantum dot fluorescent material, and the method for constructing the single emission wavelength ratiometric fluorescent probe under the assistance of ultraviolet radiation for detecting the residual metal ions in the quantum dots is constructed by utilizing the autocatalytic light modulation fluorescence property of the functionalized graphene quantum dots. The method provided by the invention can efficiently and quickly detect whether the quantum dots contain residual metal ions or not, and can quickly calculate the concentration of the residual metal ions according to a linear equation so as to judge that the metal ions in the synthesized quantum dots are completely cleaned.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (10)
1. A method for detecting residual metal ions in quantum dots is characterized by comprising the following steps:
determining the concentration and response value R of the metal ions according to the fluorescence intensity before and after the functionalized graphene quantum dot solution is added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2The corresponding relationship of (a);
according to the determined metal ion concentration and response value R2Determining the concentration of residual metal ions in the quantum dot solution to be detected according to the corresponding relation.
2. The method for detecting residual metal ions in quantum dots according to claim 1, wherein the fluorescence intensity of the functionalized graphene quantum dot solution before and after being added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation is measured by the following method:
preparing a plurality of groups of metal ion standard solutions with different concentrations, mixing each group of metal ion standard solutions with the functionalized graphene quantum dot solution respectively, measuring the fluorescence intensity of each group of mixed solutions after ultraviolet irradiation, and measuring the fluorescence intensity of each group of mixed solutions without ultraviolet irradiation;
and (3) taking the functionalized graphene quantum dot solution, measuring the fluorescence intensity of the solution after ultraviolet irradiation, and measuring the fluorescence intensity of the solution without ultraviolet irradiation.
3. The method for detecting residual metal ions in quantum dots according to claim 1, wherein the concentration and response value R of the metal ions are determined according to the fluorescence intensity of the functionalized graphene quantum dot solution before and after being added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2The step of corresponding relationship of (2), comprising:
calculating a response value R through a custom formula according to fluorescence intensities before and after the functionalized graphene quantum dot solution is added into the metal ion standard solution under ultraviolet irradiation and without ultraviolet irradiation2；
According to the response value R2Obtaining the metal ion concentration and the response value R according to the corresponding metal ion concentration2The corresponding relationship of (a);
the custom formula is shown as follows:
wherein, F1 UVThe fluorescence intensity of the functionalized graphene quantum dots added with metal ions after ultraviolet irradiation is F0 UVIs the fluorescence intensity of the functionalized graphene quantum dots after ultraviolet irradiation without adding metal ions, F1 NONEThe functionalized graphene quantum dots are added with metal ions without ultraviolet irradiationIntensity of fluorescence after emission, F0 NONEThe fluorescence intensity of the functionalized graphene quantum dots without metal ions and ultraviolet irradiation is shown, and R represents a response value.
4. The method of claim 1, wherein the determining the concentration of the metal ion and the response value R is based on the determined concentration of the metal ion and the response value R2The step of determining the concentration of the residual metal ions in the quantum dot solution to be detected according to the corresponding relationship comprises the following steps:
mixing the quantum dot solution to be measured with the functionalized graphene quantum dot solution, measuring the fluorescence intensity of the mixed solution after ultraviolet irradiation, and simultaneously measuring the fluorescence intensity of the mixed solution without ultraviolet irradiation;
taking a functionalized graphene quantum dot solution, measuring the fluorescence intensity of the solution after ultraviolet irradiation, and measuring the fluorescence intensity of the solution without ultraviolet irradiation;
according to the determined metal ion concentration and response value R2And calculating the concentration of residual metal ions in the quantum dot solution to be measured according to the corresponding relation, the fluorescence intensity under ultraviolet irradiation and the fluorescence intensity without ultraviolet irradiation obtained by measurement.
5. The method of claim 1, wherein the metal ions comprise one or more of cadmium ions and zinc ions.
6. The method for detecting residual metal ions in quantum dots according to claim 1, wherein the ultraviolet irradiation has an illumination intensity of 10 to 30 watts; and/or
The illumination time of the ultraviolet irradiation is 10-30 minutes.
7. The method of detecting residual metal ions in quantum dots according to claim 1, wherein the functionalized graphene quantum dots comprise one or more of dot-defect functionalized graphene quantum dots, single-hole-defect functionalized graphene quantum dots, multiple-hole-defect functionalized graphene quantum dots, line-defect functionalized graphene quantum dots, and out-of-plane carbon atom-introduced-defect functionalized graphene quantum dots.
8. The method of detecting residual metal ions in quantum dots according to claim 1, wherein the functionalized graphene quantum dots have one or more of carboxyl groups, alcoholic hydroxyl groups, phenolic hydroxyl groups, ether linkages, aldehyde groups, ketone groups, carbonyl groups, ester groups, acid anhydrides, and nitro groups.
9. The method for detecting residual metal ions in quantum dots according to claim 1, wherein the concentration of the functionalized graphene quantum dot solution is 10-200 mg/ml.
10. The method according to claim 2, wherein the preparing the plurality of sets of metal ion standard solutions with different concentrations is preparing metal ion standard solutions with concentration values of 10, 20, 40 and 100ug/mL respectively.
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