CN110118769A - A kind of gold nanoparticle and preparation method thereof for detecting heavy metal ion - Google Patents

Abstract

The invention discloses a gold nanoparticle for detecting heavy metal ions and a preparation method thereof. The technical method is based on agglomeration mechanism, using amino groups and/or carboxyl groups on organic compounds to form strong hydrogen bonds or through benzene on organic compounds. The ring forms a strong π-π stacking effect, which causes the agglomeration of gold nanoparticles, changes the color of the solution, and changes the peak position and absorption intensity of the plasmon resonance absorption peak on the surface of the gold nanoparticles. The change of peak position and intensity can quickly detect whether the sample contains Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions and their concentrations, and realize the detection of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions in the sample. rapid detection. The technology has the advantages of simple operation, low cost and wide application range.

Description

A kind of gold nanoparticles for detecting heavy metal ions and preparation method thereof

technical field

The invention belongs to the field of nanomaterials and ion detection, in particular to a gold nanoparticle used for detecting heavy metal ions of Cd ²⁺ , Ba ²⁺ and Pb ²⁺ and a preparation method thereof.

Background technique

With the rapid development of industry and society, the ecological environment such as soil, atmosphere and water body is seriously threatened by heavy metal ion pollution, which has attracted the attention of the majority of environmentalists. Heavy metal pollution is different from organic or biological pollution. Its pollution is difficult to eliminate, and it can accumulate in organisms through the enrichment of natural organisms. After entering the human body, it can interact with proteins and enzymes to inactivate organs and cause chronic poisoning. Or cause diseases in the human body and disorders of the nervous system and endocrine system. Therefore, heavy metal pollution poses a serious potential harm to the health of organisms.

Barium is a heavy metal that is commonly used in various industrial processes, such as electroplating, glass industry, petroleum industry, emerging pigment industry and corrosion inhibitor, etc. Its compounds are also used in paints, ceramics and rubber, etc. Ba ²⁺ ions are still the most common in water pollution to date. Ba ²⁺ ions pollute soil and water resources, especially barium salt water-soluble compounds and acid-soluble compounds have high toxicity (eg, barium sulfide). High concentrations of Ba ²⁺ ions in water can accumulate in plants and transfer to other animals in a soluble state.

Among the heavy metals, the use of lead ion Pb ²⁺ and cadmium ion Cd ²⁺ is also very common, such as barbecue food, paint, gasoline, cosmetics, etc. Cd ²⁺ and Pb ²⁺ are highly concerned by society because of their environmental pollution and harm to human beings. Today, lakes, rivers and tap water are considered natural reservoirs that provide fresh water to humans and ecosystems. Therefore, monitoring the pollution of heavy metal ions in drinking water, as well as rapid detection and identification of heavy metal ion pollution, and minimizing the risk of pollution have become inevitable choices. Traditional sensing techniques, such as AAS, ICP-AES, and ICP-MS, are sensitive and flexible, but complex, expensive, and require the use of large-scale instruments, which are not suitable for real-time detection. In order to solve these problems, electrochemical detection methods have been successfully developed for the identification of some heavy metal ions, such as anodic stripping voltammetry (ASV), which has the characteristics of high sensitivity, easy operation and low cost. A powerful tool for the detection of heavy metal ions. However, ASV on-site detection requires a sensing system and requires a small number of small instruments to complete effective detection.

So far, heavy metal ion detection methods have been developed rapidly, but different detection systems have different detection methods and applied technologies, including flame atomic absorption spectrometry, optical fiber sensors and electrochemical methods. Kanokwan Chaichana of Kasetsart University in Thailand developed some heavy metal detection methods. This detection method has the characteristics of high sensitivity, but its sample preparation is complicated and time-consuming. In recent years, the rapid development of nanotechnology has made systematic and in-depth research on the detection of heavy metal ions, and achieved certain results. In the present invention, a kind of aminobenzo-18 crown-6 derivative is synthesized, and then the derivative and 3-mercaptopropionic acid are used to co-modify gold nanoparticles, and the modified gold nanoparticles are combined with Cd ²⁺ , Ba ²⁺ , The specific action of Pb ²⁺ heavy metal ions causes changes in the color and ultraviolet absorption spectrum of gold nanoparticles, and realizes the rapid detection of Cd ²⁺ , Ba ²⁺ , and Pb ²⁺ heavy metal ions.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to aim at the deficiencies of the prior art, and to provide a method with good stability, simple operation steps, and capable of rapidly and accurately detecting Cd ²⁺ , Ba ²⁺ , and Pb ²⁺ heavy metal ions in an aqueous solution .

The technical scheme adopted by the present invention to solve the above technical problems is as follows: a method for preparing gold nanoparticles for detecting heavy metal ions, using sodium citrate, 4'-amino-benzo-18-crown-6 and 3- As reducing agent, modifier and stabilizer, mercaptopropionic acid can reduce trivalent gold to zero-valent gold, and make stable and uniform gold nanoparticles (Figure 1). The aqueous solution was added to the solution containing a certain concentration of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ions, and the color of the solution changed from red to gray or gray-black. 4'-Amino-benzo-18-crown-6 and 3-mercaptopropionic acid act as modifiers to interact with gold nanoparticles, which have rich and diverse hydrogen bonding through their amino- _NH2 or carboxyl-COOH The formation of strong hydrogen bonds or the formation of strong π-π stacking through the benzene ring will cause the agglomeration of gold nanoparticles, which will change the color of the solution, and realize the elimination of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ions in the solution. Rapid detection with naked eyes; the agglomeration of gold nanoparticles causes changes in the peak position and intensity of the surface plasmon resonance absorption peaks of gold nanoparticles to achieve quantitative detection of Cd ²⁺ , Ba ²⁺ , and Pb ²⁺ heavy metal ions in solution.

The structures of 4'-amino-benzo-18-crown-6 and 3-mercaptopropionic acid are shown in the figure below:

Schematic structure of 4'-amino-benzo-18-crown-6 and 3-mercaptopropionic acid

The preparation method of a gold nanoparticle provided by the present invention specifically comprises the following steps:

Add a certain concentration of chloroauric acid aqueous solution to the round-bottomed flask, stir and heat to boiling, quickly add sodium citrate aqueous solution, react for 5 to 15 minutes, add DMF of 4'-amino-benzo-18-crown-6 solution and ethanol solution of 3-mercaptopropionic acid to obtain a reaction mixture solution, the pH value of the reaction mixture solution is adjusted to 10-13 with HCl, the color of the solution changes from light yellow to red, and it is left to cool to room temperature to obtain gold nanoparticles , put it in the refrigerator at 0 ~ 4 ℃ and save it for later use;

The concentration of the chloroauric acid aqueous solution is 3-6 mM; the mass fraction of the sodium citrate aqueous solution is 1%;

The concentration of the DMF solution of the 4'-amino-benzo-18-crown-6 is 0.1 mM;

The concentration of the ethanol solution of 3-mercaptopropionic acid is 0.15mM;

The DMF is N,N-dimethylformamide; the substances involved in the reaction are analytically pure.

The present invention also provides the use of the gold nanoparticles, characterized in that, the gold nanoparticles are used to detect Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ions, and specifically include the following steps:

The prepared aqueous solutions of gold nanoparticles were reacted with standard solutions of heavy metal ions with different concentrations of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ , and standard cards were made according to different color changes (Fig. 2), including blank experimental results. Cards for on-site testing of samples to be tested in different environments; or

The prepared aqueous solution of gold nanoparticles was reacted with standard solutions of heavy metal ions with different concentrations of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ , and then the surface plasmon resonance absorption peaks of the reacted gold nanoparticles were tested by ultraviolet-visible absorption spectrum. Changes in peak position and intensity, draw UV-Vis absorption spectrum and standard curve (Figure 3), which are used for the detection of samples to be tested in different environments, substitute the test results into the standard curve, compare and calculate, and judge the samples to be tested. Whether there is Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions or calculate the concentration of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions in the sample to be tested, so as to realize the control of Cd ²⁺ , Ba ²⁺ , Pb ^{2 +} Quantitative detection of heavy metal ions;

The naked eye detection limit is 10nM for Cd ²⁺ , 20nM for Ba ²⁺ , and 50nM for Pb ²⁺ ;

The detection limit of UV-Vis spectrum is 5nM for Cd ²⁺ , 10nM for Ba ²⁺ , and 20nM for Pb ²⁺ ;

The sample to be detected can be mineral water, tap water or lake water.

In summary, the present invention provides a gold nanoparticle and a preparation method thereof, as well as a technology for detecting Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ions by using the prepared gold nanoparticle; the technical method is based on Agglomeration mechanism, using the amino group or carboxyl group on the modifier organic compound can form a strong specific hydrogen bond or form a strong π-π stacking effect through the benzene ring on the organic compound, thereby causing the agglomeration of gold nanoparticles and making the solution color occur. Therefore, the naked eye and UV-visible spectrophotometry can be directly used to determine whether the sample contains Cd ²⁺ , Ba ²⁺ , The content of Pb ²⁺ heavy metal ions or ions realizes the rapid detection of Cd ²⁺ , Ba ²⁺ and Pb ²⁺ heavy metal ions in the sample.

Compared with the prior art, the advantages of the present invention are: the present invention provides a gold nanoparticle, a preparation method thereof, and a variety of application technologies for ion detection. Rapid, high sensitivity, strong selectivity and on-site naked eye colorimetric detection, suitable for rapid detection of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ in mineral water, tap water, lake water and other complex systems, with a wide range of potential applications value.

Description of drawings

Fig. 1, the TEM image of the gold nanoparticle of the present invention, the particle diameter range is 10-20nm;

Figure 2. Standard cards of different detection components according to the present invention, including blank test results cards; wherein, Figure 2a is a standard card with Cd ²⁺ concentration (μM), and Figure 2b is a standard card with Ba ²⁺ (μM) concentration Standard card, Figure 2c is the standard card of Pb ²⁺ (μM) concentration;

Fig. 3, the ultraviolet-visible absorption spectrum of different detection components of the present invention and the standard curve, the standard curve is the linear relationship between the ultraviolet-visible absorption intensity ratio of the described detection metal ion and the metal ion concentration, and the ordinate is the test group The ratio of the absorption intensity corresponding to the two maximum absorption wavelengths, and the abscissa is the concentration of the corresponding metal ion;

Figure 4. Surface plasmon resonance UV-Vis absorption spectra of particles with different compositions, in the figure abc is 4'-amino-benzo-18-crown-6, 3-MPA is 3-mercaptopropionic acid, and AuNPs are gold nanoparticles .

Detailed ways

The present invention is further described below through specific embodiments, but the content of the present invention is not limited.

Production of standard cards

Step (1) 5mL of 5mM chloroauric acid solution was added to 91mL of deionized water, and under the condition of stirring and heating to boiling, 4mL of sodium citrate solution with a mass fraction of 1% was added as a reducing agent, and the reaction was performed for 15min Then, an aqueous solution of citrate-reduced and modified gold nanoparticles was prepared;

Step (2) Prepare 10 μM 3-MPA-abc solution: dissolve 0.1 mmol of 3-mercaptopropionic acid (abbreviated as 3-MPA) in 90 mL of ethanol, heat and stir to dissolve; then add 0.1 mmol to the above solution 4'-amino-benzo-18-crown-6 (abbreviated as abc) and 10 mL of DMF solvent, heated and stirred for 30 min, added ethanol to make the volume of the solution 100 mL to obtain a mixture solution; take the above mixture solution 1.0 mL, add 99 mL of ethanol for dilution to obtain a final 3-MPA-abc solution with a concentration of 10 μM;

Deionized water and cadmium nitrate were used to prepare a series of aqueous solutions of cadmium ion concentrations, with final concentrations of 0 μM, 0.01 μM, 0.02 μM, 0.05 μM, 0.1 μM, 0.3 μM, 1 μM, 5 μM, 7 μM and 8 μM standard solutions, respectively. 0.1 mL of standard solutions with different concentrations were added to each, and 0.9 mL of the aqueous solution of gold nanoparticles prepared in step (1) was added, and 10 μL of the 3-MPA-abc solution prepared in step (2) was added to obtain a mixed solution. After 20 minutes, the color of the mixed solution showed different changes, and a standard card of Cd ²⁺ ion concentration was obtained (Fig. 2a), including a card with blank experimental results.

A series of aqueous solutions of barium ion concentration were prepared with deionized water and barium nitrate, and the final concentrations were 0 μM, 0.02 μM, 0.05 μM, 0.08 μM, 0.5 μM, 1 μM, 5 μM, 8 μM, 10 μM and 15 μM standard solutions, respectively. 0.1 mL of each concentration standard solution, and 0.9 mL of the gold nanoparticle aqueous solution prepared in step (1) was added to each, and 10 μL of the 3-MPA-abc solution prepared in step (2) was added to obtain a mixed solution. minutes, the color of the mixed solution showed different changes, and the standard cards of Ba ²⁺ ion concentration were obtained (Fig. 2b), including the cards of blank experimental results.

A series of aqueous solutions of lead ion concentrations were prepared with deionized water and lead nitrate, and the final concentrations were 0 μM, 0.05 μM, 0.1 μM, 0.3 μM, 0.5 μM, 0.8 μM, 1 μM, 3 μM, 5 μM, and 6 μM standard solutions, respectively. Take 0.1 mL of standard solutions of different concentrations, add 0.9 mL of the gold nanoparticle aqueous solution prepared in step (1), and add 10 μL of the 3-MPA-abc solution prepared in step (2) to obtain a mixed solution. After standing for 20 minutes, the color of the mixed solution showed different changes, and a standard card of Pb ²⁺ ion concentration was obtained (Fig. 2c), including a card with blank experimental results.

Plot a standard curve:

The standard sample prepared above was measured by UV-Vis absorption spectrum, the change of UV-Vis absorption intensity was measured in the interval of 400-800nm, and the ratio of absorbance at 525nm and 685nm, 695nm and 690nm was recorded. Taking the concentration of the standard sample as the abscissa and the absorbance ratio as the ordinate, the standard curve was prepared (Fig. 3); through linear fitting, the linear equation of the standard curve of the Cd ²⁺ ion solution was obtained as y=0.9937 X+0.1588, R ² =0.9917; the linear equation of the standard curve of Ba ²⁺ ion solution is y=0.0524 X+0.0289, R ² =0.9984; the linear equation of the standard curve of Pb ²⁺ ion solution is y=0.0823 X+0.0213, R ² =0.9934.

Different concentrations of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ions were detected using standard cards and standard curves. The detection limit of naked eye: Cd ²⁺ was 10nM, Ba ²⁺ was 20nM, Pb ²⁺ was 50nM; UV-visible spectrum Detection limit: Cd ²⁺ is 5nM, Ba ²⁺ is 10nM, Pb ²⁺ is ^20nM ; the calculation formula of UV-Vis detection limit is K×SD/S, K=3, SD is the standard deviation, S is the slope.

Example 1

Add 10 mL of 6mM aqueous chloroauric acid solution to the round-bottomed flask, stir and heat to boiling, quickly add 20 mL of 1% sodium citrate aqueous solution, and after 15 minutes of reaction, add 30 mL of 0.1 mM 4'-amino-benzo- The DMF solution of 18-crown-6 and the ethanol solution of 30 mL of 0.15 mM 3-mercaptopropionic acid were used to obtain a reaction mixture solution. The pH value of the reaction mixture solution was adjusted to 10 with HCl, and the color of the solution changed from light yellow to red. Set to cool to room temperature to obtain gold nanoparticles. The obtained gold nanoparticles were tested by TEM, and their morphologies were shown in Figure 1.

Example 2

Add 20 mL of 3mM aqueous solution of chloroauric acid to the round-bottomed flask, stir and heat to boiling, quickly add 20 mL of aqueous solution of 1% sodium citrate by mass, and after 5 minutes of reaction, add 20 mL of 0.1 mM 4'-amino-benzo-18 -DMF solution of crown ether-6 and 30mL of ethanol solution of 0.15mM 3-mercaptopropionic acid to obtain a reaction mixture solution, the pH value of which was adjusted with HCl to 13, the color of the solution changed from light yellow to red, and it was left to cool to room temperature. gold nanoparticles.

Example 3

Add 20 mL of 5mM aqueous chloroauric acid solution to the round-bottomed flask, stir and heat to boiling, quickly add 30 mL of 1% sodium citrate aqueous solution, and after 10 minutes of reaction, add 40 mL of 0.1 mM 4'-amino-benzo- DMF solution of 18-crown-6 and 40mL of ethanol solution of 0.15mM 3-mercaptopropionic acid, the pH value of the reaction mixture solution was adjusted to 12 with HCl, the color of the solution changed from light yellow to red, and it was left to cool to room temperature to obtain Gold Nanoparticles.

Example 4

Detection of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions in "mineral water"

(a) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution without Cd ^ions (within the detection range) as a comparison solution, mix the comparison solution and "mineral water" equal volumes of The detection solution was added to the two aqueous solutions of gold nanoparticles to form mixed solution A and mixed solution B; after 15 minutes of reaction, the colors of mixed solution B and mixed solution A were compared. There are Cd ²⁺ ions in the "mineral water" solution, if there is no color change, there is no Cd ²⁺ ions in the "mineral water" solution to be detected, or compare and calculate the UV-visible absorption intensity of mixed solution B and mixed solution A and Peak, if its absorption intensity and peak value change, there are Cd ²⁺ ions in the “mineral water” solution to be detected. If there is no change, there is no Cd ²⁺ ion in the “mineral water” solution to be detected.

(b) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution without Ba ^ions (within the detection range) as a comparison solution, mix the comparison solution and "mineral water" with equal volumes of the The detection solution was added to the two aqueous solutions of gold nanoparticles to form mixed solution C and mixed solution D; after 15 minutes of reaction, the colors of mixed solution D and mixed solution C were compared. There are Ba ²⁺ ions in the "mineral water" solution. If there is no color change, then there are no Ba ²⁺ ions in the "mineral water" solution to be detected. If the absorption intensity and peak value change, there are Ba ²⁺ ions in the “mineral water” solution to be detected. If there is no change, there are no Ba ²⁺ ions in the “mineral water” solution to be detected.

(c)) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution without Pb ²⁺ ions (within the detection range) as a contrast solution, mix the contrast solution and "mineral water" equal volumes of The solution to be detected is respectively added to the two aqueous solutions of gold nanoparticles to form mixed solution E and mixed solution F; after 15 minutes of reaction, the colors of mixed solution F and mixed solution E are compared, if the color changes, then to be detected There are Pb ²⁺ ions in the "mineral water" solution of the sample, if there is no color change, then there is no Pb ²⁺ ions in the "mineral water" solution to be detected, or compare and calculate the UV-visible absorption of the mixed solution F and the mixed solution E Intensity and peak value, if the absorption intensity and peak value change, there is Pb ²⁺ ion in the “mineral water” solution to be detected, if there is no change, then there is no Pb ²⁺ ion in the “mineral water” solution to be detected .

Example 5

Detection of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions in "tap water"

(a) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution that does not contain Cd ^ions (within the detection range) as a comparison solution, and use the comparison solution and "tap water" equal volumes of the to-be-detected The solutions were added to the two aqueous solutions of gold nanoparticles to form mixed solution A and mixed solution B; after 15 minutes of reaction, compare the colors of mixed solution B and mixed solution A. There are Cd ²⁺ ions in the "tap water" solution, if there is no color change, then there are no Cd ²⁺ ions in the "tap water" solution to be detected, or compare and calculate the UV-visible absorption intensity and peak value of mixed solution B and mixed solution A, If its absorption intensity and peak value change, Cd ²⁺ ions exist in the “tap water” solution to be detected. If there is no change, there are no Cd ²⁺ ions in the “tap water” solution to be detected.

(b) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution without Ba ^ions (within the detection range) as a comparison solution, mix the comparison solution and "tap water" equal volumes of the solution to be detected The solutions were added to the two aqueous solutions of gold nanoparticles to form mixed solution C and mixed solution D; after 15 minutes of reaction, compare the colors of mixed solution D and mixed solution C. There are Ba ²⁺ ions in the "tap water" solution, if there is no color change, then there are no Ba ²⁺ ions in the "tap water" solution to be detected, or compare and calculate the UV-visible absorption intensity and peak value of mixed solution D and mixed solution C, If its absorption intensity and peak value change, there are Ba ²⁺ ions in the "tap water" solution to be detected. If there is no change, there are no Ba ²⁺ ions in the "tap water" solution to be detected.

(c)) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution without Pb ^ions (within the detection range) as a comparison solution, mix the comparison solution and "tap water" equal volumes of The detection solution is respectively added to the two aqueous solutions of gold nanoparticles to form mixed solution E and mixed solution F; after 15 minutes of reaction, compare the colors of mixed solution F and mixed solution E, if the color changes, then the There are Pb ²⁺ ions in the "tap water" solution, if there is no color change, then there are no Pb ²⁺ ions in the "tap water" solution to be detected, or compare and calculate the UV-visible absorption intensity and peak value of the mixed solution F and the mixed solution E , if its absorption intensity and peak value change, there is Pb ²⁺ ion in the "tap water" solution to be detected, if there is no change, there is no Pb ²⁺ ion in the "tap water" solution to be detected.

Example 6

Detection of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions in "lake water"

(a) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution that does not contain Cd ^ions (within the detection range) as a comparison solution, and use the comparison solution and "lake water" equal volumes of the to-be-detected The solutions were added to the two aqueous solutions of gold nanoparticles to form mixed solution A and mixed solution B; after 15 minutes of reaction, compare the colors of mixed solution B and mixed solution A. There are Cd ²⁺ ions in the "lake water" solution, if there is no color change, then there is no Cd ²⁺ ions in the "lake water" solution to be detected, or compare and calculate the UV-visible absorption intensity and peak value of mixed solution B and mixed solution A, If its absorption intensity and peak value change, there are Cd ²⁺ ions in the “lake water” solution to be detected. If there is no change, there are no Cd ²⁺ ions in the “lake water” solution to be detected.

(b) Take two equal volumes of aqueous solutions of the prepared gold nanoparticles; prepare an aqueous solution without Ba ^ions (within the detection range) as a comparison solution, and use the comparison solution and "lake water" equal volumes of the to-be-detected The solutions were respectively added to the two aqueous solutions of gold nanoparticles to form mixed solution C and mixed solution D; after 15 minutes of reaction, compare the colors of mixed solution D and mixed solution C. There are Ba ²⁺ ions in the "lake water" solution, if there is no color change, then there are no Ba ²⁺ ions in the "lake water" solution to be detected, or compare and calculate the ultraviolet-visible absorption intensity and peak value of the mixture D and the mixture C, If its absorption intensity and peak value change, there are Ba ²⁺ ions in the "lake water" solution to be detected. If there is no change, there are no Ba ²⁺ ions in the "lake water" solution to be detected.

(c)) Take two equal volumes of the same aqueous solution of the prepared gold nanoparticles; prepare an aqueous solution without Pb ^ions (within the detection range) as a comparison solution, mix the comparison solution and "lake water" equal volumes of the The detection solution is respectively added to the two aqueous solutions of gold nanoparticles to form mixed solution E and mixed solution F; after 15 minutes of reaction, compare the colors of mixed solution F and mixed solution E, if the color changes, then the There are Pb ²⁺ ions in the "lake water" solution. If there is no color change, then there are no Pb ²⁺ ions in the "lake water" solution to be detected, or compare and calculate the UV-visible absorption intensity and peak value of the mixed solution F and the mixed solution E. , if its absorption intensity and peak value change, there are Pb ²⁺ ions in the “lake water” solution to be detected; if there is no change, there is no Pb ²⁺ ion in the “lake water” solution to be detected.

Example 7

Identify and differentiate Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions

0.9mL aqueous solution of gold nanoparticles, add 0.1mL aqueous solution of 0.1mM cadmium, barium, lead ion concentration to different sample tubes, after mixing, add 10uL 10μM 3-MPA-abc solution, react for 15min, The UV-Vis absorption spectrum test was carried out, and the results are shown in Figure 4. Different test components have different UV-Vis absorption intensities, different peaks and different color changes, which can distinguish Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metals ion.

Example 8

Using ultraviolet-visible absorption spectrometer, the ratio of A _695nm /A _525nm of the sample to be tested containing Cd ²⁺ ions was determined to be 0.6, and substituted into the linear equation of the standard curve of Cd ²⁺ ion solution y=0.9937 X+0.1588, it can be calculated that X= 0.4440, that is, the concentration of Cd ²⁺ ions is 0.4440 μM;

Example 9

Using UV-Vis absorption spectrometer, determine the ratio of A _685nm /A _525nm of the sample containing Ba ²⁺ ions to be 0.6, and substitute it into the linear equation of the standard curve of Ba ²⁺ ion solution y=0.0524 X+0.0289, it can be calculated that X= 10.90, that is, the concentration of Ba ²⁺ ions is 10.90 μM;

Example 10

Using UV-Vis absorption spectrometer, the ratio of A _690nm /A _525nm of the sample to be tested containing Pb ²⁺ ions was determined to be 0.6, and substituted into the linear equation y=0.0823 X+0.0213 of the standard curve of the Pb ²⁺ ion solution, X= 7.032, that is, the concentration of Pb ²⁺ ions is 7.032 μM;

The above embodiments describe the technical solutions of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Anything done within the scope of the principles of the present invention Any modification and improvement, etc., should be included within the protection scope of the present invention.

Claims (2)

1. a preparation method for detecting the gold nanoparticles of heavy metal ions, is characterized in that, utilizes 4'-amino-benzo-18-crown-6 and 3-mercaptopropionic acid as modifiers to prepare gold nanoparticles , which includes the following steps: Add a certain concentration of chloroauric acid aqueous solution to the round-bottomed flask, stir and heat to boiling, quickly add a certain concentration of sodium citrate aqueous solution, and react for 5-15 minutes, add a certain concentration of modifier 4'-amino-benzo-18 - the DMF solution of crown ether-6 and an appropriate amount of ethanol solution of 3-mercaptopropionic acid to obtain a reaction mixture solution, the pH value of the reaction mixture solution is adjusted to 10-13 with HCl, the color of the solution changes from light yellow to red, and it is left to stand Cool to room temperature to obtain gold nanoparticles, which are stored in a refrigerator at 0 to 4°C for later use; The concentration of the chloroauric acid aqueous solution is 3-6 mM; The mass fraction of the sodium citrate aqueous solution is 1%; The concentration of the DMF solution of the 4'-amino-benzo-18-crown-6 is 0.1 mM; The concentration of the 3-mercaptopropionic acid ethanol solution is 0.15mM; The DMF is N,N-dimethylformamide; The substances participating in the reaction are of analytical grade. 2. a kind of purposes of the gold nanoparticle that the method as claimed in claim 1 makes, is characterized in that, described gold nanoparticle is used to detect Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ion, specifically comprises the following steps : The prepared aqueous solution of gold nanoparticles is reacted with standard solutions of heavy metal ions of different concentrations of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ respectively, and standard cards are made according to different color changes, including cards with blank test results, used for On-site testing of samples to be tested in different environments; or; The prepared aqueous solution of gold nanoparticles was reacted with standard solutions of heavy metal ions with different concentrations of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ , and then the surface plasmon resonance absorption peaks of the reacted gold nanoparticles were tested by ultraviolet-visible absorption spectrum. Changes in peak position and intensity, draw UV-vis absorption spectrum and standard curve, which are used for the detection of samples to be tested in different environments, substitute the test results into the standard curve, compare and calculate, and determine whether there is Cd ² in the sample to be tested ⁺ , Ba ²⁺ , Pb ²⁺ ions or calculate the concentration of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ ions in the sample to be tested, so as to realize the concentration of Cd ²⁺ , Ba ²⁺ , Pb ²⁺ heavy metal ions in the sample Quantitative detection; The naked eye detection limit is 10nM for Cd ²⁺ , 20nM for Ba ²⁺ , and 50nM for Pb ²⁺ ; The detection limit of UV-Vis spectrum is 5nM for Cd ²⁺ , 10nM for Ba ²⁺ , and 20nM for Pb ²⁺ ; The sample to be detected can be mineral water, tap water or lake water.