CN110243797B - Method for detecting cigarettes by using fluorescent carbon quantum dots - Google Patents
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- CN110243797B CN110243797B CN201910618322.5A CN201910618322A CN110243797B CN 110243797 B CN110243797 B CN 110243797B CN 201910618322 A CN201910618322 A CN 201910618322A CN 110243797 B CN110243797 B CN 110243797B
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Abstract
The invention belongs to the technical field of distinguishing and detecting cigarettes, and particularly relates to a method for detecting cigarettes by using fluorescent carbon quantum dots. Dissolving fluorescent carbon quantum dots in water, respectively adding silver ion solutions with different concentrations and a cigarette extracting solution, and monitoring the fluorescence intensity of the solutions, wherein the fluorescent carbon quantum dots are carbon quantum dots with silver ion specific fluorescence response. The carbon quantum dots with silver ion specific fluorescent response, which are prepared by the invention, can be used for constructing a fluorescent sensor array through the change of the fluorescence intensity of a carbon quantum dot-silver ion-cigarette extract sensing system, so that different cigarettes can be distinguished and detected. The carbon quantum dots have the characteristics of excellent chemical stability, good fluorescence performance, simple preparation method and process, easiness in operation and the like, and the constructed sensing system has the advantages of high detection speed, high result accuracy and reliability, low preparation cost and easiness in popularization.
Description
Technical Field
The invention belongs to the technical field of distinguishing and detecting cigarettes, and particularly relates to a method for detecting cigarettes by using fluorescent carbon quantum dots.
Background
Smoking can pose serious health risks, including lung cancer, chronic obstructive pulmonary disease, cardiovascular disease, peptic ulcers, and other health problems. The content of main components (such as sugar, organic acid and nicotine) of cigarette tobacco directly affects the types of cigarettes and the content of toxic chemicals in cigarette smoke, so that different types of cigarettes have different harmfulness degrees on human bodies. Therefore, an effective method must be established to monitor and identify the different categories of cigarettes.
In recent years, most of the cigarette distinguishing and detecting methods focus on the use of electronic sensing systems, and the volatile gas of the cigarettes is detected and the corresponding data is analyzed, so that the identification of different types of cigarettes is realized. However, the sensing system has many disadvantages of complicated structure, complex operation, unstable measurement result, and easy influence of external environment (temperature, humidity, etc.). Therefore, the development of simple solution-based sensing systems is necessary. The sensing system has no any complicated condition control device, the testing condition is easy to control, and the measuring result is more reliable.
Disclosure of Invention
The invention aims to provide a method for detecting different cigarettes aiming at the problems in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme that the method for detecting the cigarettes by using the fluorescent carbon quantum dots is characterized in that the fluorescent carbon quantum dots are dissolved in water, a silver ion solution and a cigarette extracting solution are respectively added, and the fluorescence intensity of the solution is monitored, wherein the fluorescent carbon quantum dots are carbon quantum dots with silver ion specific fluorescence response.
Preferably, in the method, the concentration of the aqueous solution of the carbon quantum dots with silver ion specific fluorescence response is 0.1-100 mg/mL.
Preferably, in the above method, the preparation method of the cigarette extract is as follows: drying tobacco leaves of cigarettes, grinding into powder, dissolving the powder in water according to the material-liquid ratio of 1g:0.1-0.3L, refluxing and stirring for 1 hour at 80 ℃ to obtain a tobacco crude extract, and centrifuging to obtain a filtrate to obtain the cigarette extract.
Preferably, in the above method, the carbon quantum dot with silver ion specific fluorescence response is prepared as follows:
1) mixing amino acid and urea, and dissolving in ultrapure water to obtain a mixed solution;
2) placing the mixed solution obtained in the step 1) in a microwave reactor for heating reaction;
3) cooling to room temperature, dissolving with ultrapure water, centrifuging, collecting supernatant, dialyzing, and freeze-drying to obtain the target product.
Preferably, in the above method, the amino acid is one of glycine, alanine or serine.
Preferably, the above method, in terms of mole ratio, amino acid: urea is 1: 4-6.
Preferably, in the method, the heating reaction in the step 2) has a microwave power of 600-800W, a temperature of 100-200 ℃ and a microwave action time of 3-4 minutes.
Preferably, the dialysis bag for dialysis described in the above method, step 3), has a molecular weight cut-off of 14 kDa.
Preferably, in the method, the freeze drying in the step 3) is performed at-45 to-50 ℃ for 10 to 12 hours.
The beneficial effects of the invention are as follows: the carbon quantum dots provided by the invention have sensitive response to silver ions, a fluorescence sensor array can be constructed through the fluorescence intensity change of a carbon quantum dot-silver ion-tobacco extract sensing system, and different cigarettes can be reasonably classified through fluorescence data processing. The cigarette distinguishing and detecting method based on the carbon quantum dots has the advantages of excellent chemical stability, good fluorescence performance, high detection speed, high result accuracy and reliability; the preparation method has the advantages of simple process, easy operation, low preparation cost and easy popularization.
Drawings
Fig. 1 is a transmission electron micrograph of a carbon quantum dot having a silver ion-specific fluorescent response prepared in example 1.
Fig. 2 is a uv-vis absorption spectrum of the carbon quantum dot having a silver ion specific fluorescent response prepared in example 1.
Fig. 3 is a fluorescence emission spectrum of the carbon quantum dot having a silver ion specific fluorescence response prepared in example 1.
Fig. 4 is an infrared absorption spectrum of the carbon quantum dot having a silver ion specific fluorescence response prepared in example 1.
Fig. 5 is an X-ray photoelectron spectrum of a carbon quantum dot having a silver ion-specific fluorescent response prepared in example 1.
Fig. 6 is a graph showing the fluorescence response of carbon quantum dots having silver ion-specific fluorescence responses to metal ions prepared in example 1.
FIG. 7 is a graph showing the fluorescence response of carbon quantum dots having silver ion-specific fluorescence responses to silver ions prepared in example 1.
FIG. 8 is a fluorescence response diagram (fluorescence fingerprint) of the carbon quantum dot-metal ion sensing system to 29 different cigarette tobacco extract solutions.
Fig. 9 is a principal component analysis scatter plot of carbon quantum dots-silver ions-tobacco extract sensor array fluorescence data.
Detailed Description
Example 1 preparation of carbon quantum dots with silver ion specific fluorescent response
Weighing 0.4g of glycine and 1.2g of urea, uniformly mixing and dissolving in 10mL of ultrapure water, placing in a microwave reactor, setting the microwave power at 600W, setting the temperature at 160 ℃, heating for 4 minutes by microwave, cooling to room temperature after the reaction is finished, dissolving in 10mL of ultrapure water, centrifuging at 10000 r/min for 3 minutes, taking the supernatant, dialyzing for 48 hours by using a dialysis bag with the molecular weight cutoff of 14kDa, taking out the solution, freeze-drying at-48 ℃ for 12 hours to obtain the carbon quantum dots with silver ion specific fluorescence response, and storing at 2-8 ℃.
Example 2 detection of carbon quantum dots with silver ion specific fluorescent response
1. The carbon quantum dots having specific fluorescent response to silver ions, prepared in example 1, were subjected to transmission electron microscope scanning, and the results are shown in fig. 1, and as can be seen from fig. 1, the prepared carbon quantum dots have an average particle size of 8nm, are uniformly distributed, and are uniformly distributed as spherical particles.
2. The ultraviolet-visible light absorption spectrum detection of the carbon quantum dots having specific fluorescent response to silver ions prepared in example 1 showed that, as shown in fig. 2, two absorption peaks, i.e., pi-pi transition and n-pi transition, were observed at wavelengths of about 210nm and about 330nm, respectively, as shown in fig. 2, which confirmed the formation of the carbon quantum dots.
3. The carbon quantum dots with specific fluorescent response to silver ions prepared in example 1 were subjected to fluorescence optimum excitation wavelength detection: the carbon quantum dot prepared in example 1 was prepared into a solution with a concentration of 400mg/mL with ultrapure water, and a fluorescence spectrum was measured in a fluorescence spectrometer using an excitation wavelength of 300-370nm, and the result is shown in FIG. 3, from which it can be seen in FIG. 3 that the fluorescence intensity of the carbon quantum dot prepared in example 1 increases first and then decreases at the excitation wavelength of 300-370nm, and the optimal excitation wavelength is 330 nm.
4. The infrared absorption spectrum detection is performed on the carbon quantum dots with specific fluorescence response to silver ions, which are prepared in example 1, and the result is shown in fig. 4, and as can be seen from fig. 4, the surfaces of the prepared carbon quantum dots are rich in-NH2And a hydrophilic functional group such as-COOH.
5. The carbon quantum dot prepared in example 1 and having a specific fluorescent response to silver ions was subjected to X-ray photoelectron spectroscopy, and the result is shown in fig. 5, and as can be seen from fig. 5, the mass ratio of C, N, O elements in the prepared carbon quantum dot is 50.49:23.83: 25.68.
Example 3 application of carbon quantum dots with silver ion specific fluorescent response
1. Fluorescence responsiveness of carbon quantum dots with silver ion specific fluorescence response to metal ion solution
The carbon quantum dots having a silver ion specific fluorescent response prepared in example 1 were prepared into a solution with ultrapure water, the absorbance a of the carbon quantum dot solution was made 0.1 by adding ultrapure water at a wavelength of 330nm in an ultraviolet-visible spectrometer, the carbon quantum dot solution having an absorbance of 0.1 was divided into 11 groups of 5mL each, different metal ion solutions having the same volume concentration of 50mmol/L were added, and the change in fluorescence of each group of solutions at a wavelength of 330nm in the light source was observed. The results are shown in FIG. 6, I0The highest intensity value of the fluorescence of the carbon quantum dot and the highest intensity value of the fluorescence of the metal ion are shown in fig. 6, and it can be seen from fig. 6 that the prepared carbon quantum dot is sensitive to the silver ion, which shows that the carbon quantum dot prepared in example 1 has specific fluorescence response to the silver ion.
2. Fluorescence responsiveness of carbon quantum dots with silver ion specific fluorescence response to silver ion solutions with different concentrations
The carbon quantum dot sample prepared in example 1 was dissolved in ultrapure water, and ultrapure water was added to a light source at a wavelength of 330nm in an ultraviolet-visible spectrometer so that the absorbance a of the solution became 0.1, and the carbon quantum dot solution having an absorbance of 0.1 was divided into 16 groups of 5mL each, and silver ion solutions having different volume concentrations of 50mmol/L were added to each group, and the change in fluorescence of each group of solutions at a wavelength of 330nm was observed. The results are shown in FIG. 7A, I0Is the amount of carbonThe highest intensity value of the fluorescence of the sub-dots, I, is the highest intensity value of the fluorescence after the metal ions are added, as can be seen from B in fig. 7, the carbon quantum dots prepared in example 1 are sensitive to the silver ions, which indicates that the carbon quantum dots prepared in example 1 have sensitive fluorescence response to the silver ions.
3. Four carbon quantum dot-metal ion fluorescent sensors are used for carrying out fluorescent response test on different types of cigarette tobacco extracting solutions
Carbon quantum dots with absorbance a of 0.1 of 5mL were combined with silver ion solutions of 10 μmol/L, 40 μmol/L, 70 μmol/L, and 100 μmol/L to form fluorescence sensors, which were designated as S1 to S4, respectively, 5 μ L of tobacco extract was added to each sensor, and the change in fluorescence of each group of solutions at a wavelength of 330nm of a light source was observed. The basic information of the cigarettes used in the experiment is shown in table 1. I in FIG. 80The highest intensity value of the fluorescence of the carbon quantum dot-silver ion fluorescence sensor is shown, and the highest intensity value of the fluorescence of the tobacco extract added is shown in the figure 8, and the four fluorescence sensors respond to different cigarette tobacco extracts and have different response degrees, which shows that the prepared carbon quantum dot sensor array has the capability of distinguishing and identifying different cigarettes.
4. Performing principal component analysis on the carbon quantum dot fluorescence sensor array:
the prepared carbon quantum dot fluorescent sensor array was subjected to principal component analysis on data of cigarette test using SPSS software. The resulting scatter plots are shown in fig. 9, where five scatter plots are obtained from five replicates of each cigarette in fig. 9, and as shown in fig. 9, the flue-cured cigarette and cigar sample data points are distributed on the left and right sides of fig. 9, respectively, while the mixed cigarettes are distributed centrally in the middle area of fig. 9, with each cigarette having its own scatter plot area where the data points associated with each cigarette are clustered together and distinguished from the data points of other types of cigarettes. This demonstrates the ability of the prepared carbon quantum dot sensor array to identify different cigarettes differently.
When the silver ion solution is added into the solution containing the carbon quantum dots with specific fluorescent response to silver ions, the fluorescent emission intensity of the silver ion solution is weakened; the addition of tobacco extract to the fluorescence-quenched carbon quantum dot solution results in a continued reduction in the fluorescence emission intensity. The fluorescence sensor array is constructed through the fluorescence intensity change of the carbon quantum dot-silver ion-tobacco extract sensing system, and the SPSS software is used for carrying out principal component analysis on the data tested by the carbon quantum dot fluorescence sensor array, so that the cigarettes are subjected to chemical classification.
TABLE 1 basic information of cigarettes
Claims (3)
1. A method for detecting cigarettes by using fluorescent carbon quantum dots is characterized in that the fluorescent carbon quantum dots are dissolved in water, silver ion solution and cigarette extracting solution are respectively added, the fluorescence intensity of the solution is monitored, the fluorescent carbon quantum dots are carbon quantum dots with silver ion specific fluorescence response, a fluorescent sensor array is constructed through the fluorescence intensity change of a carbon quantum dot-silver ion-cigarette extracting solution sensing system, and SPSS software is used for carrying out principal component analysis on data tested by the fluorescent sensor array, so that different cigarettes are classified;
wherein the concentration of the aqueous solution of the fluorescent carbon quantum dots is 0.1-100 mg/mL; the preparation method of the cigarette extracting solution comprises the following steps: drying tobacco leaves of cigarettes, grinding into powder, dissolving the powder in water according to the material-liquid ratio of 1g:0.1-0.3L, refluxing and stirring for 1 hour at 80 ℃ to obtain a tobacco crude extract, and centrifuging to obtain a filtrate to obtain a cigarette extract;
the preparation method of the carbon quantum dot with silver ion specific fluorescence response comprises the following steps:
1) mixing amino acid and urea, and dissolving in ultrapure water to obtain a mixed solution; the amino acid is one of glycine, alanine or serine;
2) placing the mixed solution obtained in the step 1) in a microwave reactor for heating reaction;
3) cooling to room temperature, dissolving with ultrapure water, centrifuging, collecting supernatant, dialyzing, and freeze-drying to obtain target product;
heating reaction in the step 2), wherein the microwave power is 600-800W, the temperature is 100-200 ℃, and the microwave action time is 3-4 minutes;
the freeze drying in the step 3) is freeze drying for 10-12 hours at-45 to-50 ℃.
2. The method of claim 1, wherein the molar ratio of amino acid to urea is 1: 4-6.
3. The method of claim 1, wherein the dialysis bag of step 3) has a molecular weight cut-off of 14 kDa.
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