Graphene quantum dot, preparation method, glyphosate detection method and detection device

Abstract

The application provides a graphene quantum dot, a preparation method, a glyphosate detection method and a detection device. The graphene quantum dot has two emission wavelengths of 425nm and 525nm, and the color of light emitted by the graphene quantum dot can be used to preliminarily identify the concentration range of glyphosate. The intensity of the 425nm and 525nm emission light changes synchronously with the intensity of the excitation light, so the intensity ratio between the 425nm and 525nm light is hardly affected by the intensity of the excitation light. In addition, when other impurities exist in the to-be-detected liquid, the intensity ratio between the 425nm and 525nm light is hardly affected, and the intensity ratio between the 425nm and 525nm light is almost only affected by the concentration of glyphosate, so that the graphene quantum dot can be used to quantitatively detect the concentration of glyphosate by using a double-peak intensity ratio method, so that a more accurate concentration value of glyphosate can be obtained.

Description

Technical Field

[0001] This invention relates to the field of graphene quantum dots, and in particular to a graphene quantum dot, a preparation method, a glyphosate detection method, and a detection device. Background Technology

[0002] In agriculture, pesticides, such as glyphosate, play a vital role in ensuring healthy crop growth and guaranteeing grain yields. However, the extensive use of glyphosate often results in glyphosate residues on crops, and excessive glyphosate increases the risk of cancer in humans. Therefore, the detection and identification of glyphosate is of paramount importance.

[0003] However, at present, the detection cost of glyphosate is very high, and the detection process is easily interfered with by other impurities, resulting in insufficient accuracy. Summary of the Invention

[0004] Therefore, it is necessary to address the issues of high cost and insufficient accuracy in glyphosate detection by providing a graphene quantum dot, its preparation method, a glyphosate detection method, and a detection device.

[0005] The technical solution provided by this invention is as follows:

[0006] A type of graphene quantum dot, with the chemical formula:

[0007] The graphene quantum dots of this invention are water-soluble quantum dots, allowing the graphene quantum dots to detect the concentration of water-soluble glyphosate. The graphene quantum dots are capable of detecting the concentration of glyphosate at least using the bimodal intensity ratio method. The lower limit of glyphosate concentration detection by the graphene quantum dots is not higher than 30 nM, and there is a linear relationship between the concentration of glyphosate and the bimodal intensity ratio of the graphene quantum dots when the concentration is not higher than 30 μM.

[0008] A method for preparing graphene quantum dots includes the following steps:

[0009] Tris(hydroxymethyl)aminomethane and resorcinol were mixed and dissolved in water, and then heated in a reaction vessel. The reaction product was centrifuged and filtered, and the filtrate was dialyzed to obtain graphene quantum dots.

[0010] In this invention, the molar ratio of tris(hydroxymethyl)aminomethane and resorcinol is 1:1, the hydrothermal temperature is 160°C, and the hydrothermal time is not less than 5 hours.

[0011] In this invention, each 2 mmol of tris(hydroxymethyl)aminomethane and 2 mmol of resorcinol are dissolved in at least 20 ml of water.

[0012] A method for detecting glyphosate involves dissolving graphene quantum dots in a test solution and then irradiating it with 365nm excitation light to obtain 425nm and 525nm emission light. The concentration of glyphosate in the test solution is determined based at least on the intensity ratio between the 425nm and 525nm emission light.

[0013] The test solution described in this invention contains one or more of the following: metal ions, acephate, carbendazim, dimethoate, malathion, trichlorfon, and paraoxon.

[0014] A glyphosate detection device includes a 365nm laser, a nitrocellulose substrate, and a detection element. The nitrocellulose substrate extends along a first direction, and the detection element is located in the middle of the nitrocellulose substrate and is attached to the nitrocellulose substrate. The 365nm laser is positioned toward the detection element, and the detection element is made of graphene quantum dots.

[0015] The detection element of the present invention extends along a second direction, and both ends of the detection element are located at the edge of the nitrocellulose substrate. The second direction is inclined relative to the first direction.

[0016] The glyphosate detection device of the present invention further includes a camera terminal, which is positioned facing the detection element and has an RGB analysis module.

[0017] The beneficial effects of this invention are as follows:

[0018] The graphene quantum dots provided by this invention have excellent water solubility, and can then react smoothly with glyphosate in aqueous solution, causing a change in fluorescence intensity and enabling the detection of glyphosate.

[0019] Graphene quantum dots have two emission wavelengths, 425nm and 525nm. Glyphosate can induce changes in the intensity of the 425nm emitted light from graphene quantum dots, while the intensity of the 525nm emitted light hardly changes. In addition, the 365nm laser used to excite graphene quantum dots is not visible light. Therefore, the concentration range of glyphosate can be initially identified by the naked eye based on the color of the light emitted by graphene quantum dots.

[0020] The intensity of the emitted light at 425nm and 525nm changes synchronously with the intensity of the excitation light. Therefore, the intensity ratio between the 425nm and 525nm rays is almost unaffected by the excitation light intensity. Furthermore, the presence of other impurities in the test solution has virtually no impact on the intensity ratio between the 425nm and 525nm rays. The intensity ratio between the 425nm and 525nm rays is almost solely affected by the glyphosate concentration. Consequently, the graphene quantum dots of this invention allow for the quantitative detection of glyphosate concentration using the bimodal intensity ratio method, thereby obtaining a more accurate concentration value for glyphosate.

[0021] The method for preparing graphene quantum dots and the method for detecting glyphosate provided by this invention are both very simple, do not use precious metals such as gold and silver, and have low preparation and detection costs. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating the synthesis reaction process of graphene quantum dots in Example 1 of the present invention;

[0023] Figure 2 The absorption spectrum, PL spectrum, and PLE spectrum of the graphene quantum dots in Example 1 of this invention are shown below.

[0024] Figure 3 This is a bar chart showing the changes in emitted light intensity of graphene quantum dots after different times of ultraviolet irradiation, in salt solutions of different concentrations, and after different times of natural storage in Example 1 of the present invention.

[0025] Figure 4 The emission spectra of graphene quantum dots and glyphosate of different concentrations mixed in Example 1 of this invention;

[0026] Figure 5 In Embodiment 1 of the present invention (I) 425 / I 525 ) / (I 425 / I 525 )0 Graph showing the change in glyphosate concentration (excitation light intensity 2000);

[0027] Figure 6 In Embodiment 1 of the present invention (I) 425 / I 525 ) / (I 425 / I 525 )0 Graph showing the change in glyphosate concentration (excitation light intensity is 1000);

[0028] Figure 7 In Example 1 of this invention, the excitation light intensities are 1000 and 2000 respectively (I 425 / I 525 ) / (I 425 / I 525 )0 Graph showing the variation of glyphosate concentration (0-200 μM);

[0029] Figure 8 In Example 1 of this invention, the excitation light intensities are 1000 and 2000 respectively (I 425 / I 525 ) / (I 425 / I 525 )0. Graph showing the change in glyphosate concentration (0-30 nM);

[0030] Figure 9 In Example 1 of this invention, graphene quantum dots react with different substances (I) 425 / I 525 ) / (I 425 / I 525 A comparison chart of the values ​​of 0. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Example 1:

[0033] This embodiment provides a graphene quantum dot with the chemical formula [chemical formula not provided]. As can be seen from the chemical formula, the graphene quantum dots provided in this embodiment have abundant hydroxyl and amino groups, thus exhibiting excellent water solubility. That is, these graphene quantum dots are water-soluble quantum dots. It is understood that since glyphosate is also a water-soluble reagent, the liquid required for glyphosate concentration detection is usually an aqueous solution. The water-soluble graphene quantum dots provided in this embodiment can fully contact glyphosate in aqueous solutions, thereby achieving higher accuracy in detecting glyphosate concentration values.

[0034] This embodiment also provides a method for preparing the above-mentioned graphene quantum dots, including the following steps:

[0035] Step 101: Dissolve 2 mmol of tris(hydroxymethyl)aminomethane and 2 mmol of resorcinol in 20 ml of deionized water, and then transfer to a 100 ml reaction vessel;

[0036] Step 102: The reaction was carried out inside the reactor at 160℃ for 5 hours, and then cooled to room temperature. The reaction process of tris(hydroxymethyl)aminomethane and resorcinol is as follows. Figure 1 As shown;

[0037] Step 103: Centrifuge the residue after the reaction at 8000 rpm for 15 min, and then filter it through a 0.22 μm microporous membrane. At this time, the water-soluble graphene quantum dots to be prepared in this embodiment exist in the filtrate, so only the filtrate is retained.

[0038] Step 104: Dialyze the filtrate using a 100-500 Da dialysis bag for 48 hours to obtain graphene quantum dots.

[0039] It is particularly noteworthy that both tris(hydroxymethyl)aminomethane and resorcinol have good water solubility, and based on the experience of those skilled in the art, the graphene quantum dots synthesized from them are generally water-insoluble quantum dots. However, the graphene quantum dots actually obtained in this embodiment are water-soluble quantum dots, which clearly contradicts the experience of those skilled in the art.

[0040] See Figure 2 In this embodiment, the excitation wavelength of the graphene quantum dots is 365nm, and the emission wavelengths are 425nm and 525nm. 365nm is a non-visible light wavelength, while 425nm and 525nm are visible light wavelengths. Therefore, researchers can only observe the emitted light of the graphene quantum dots with the naked eye and will not be disturbed by the excitation light.

[0041] See Figure 3 In this embodiment, the graphene quantum dots emitted light showed no significant change in intensity when irradiated with ultraviolet light for 0-18 hours. Similarly, the emission intensity remained unchanged when the graphene quantum dots were dissolved in sodium chloride solutions of varying concentrations (0-2.4 mol / L). Furthermore, the emission intensity remained largely unchanged after 24 days of natural storage, demonstrating the excellent luminescent stability of the graphene quantum dots provided in this embodiment.

[0042] But see Figure 4 When the graphene quantum dots of this embodiment were mixed with glyphosate at different concentrations (0-200 μM), the emission spectrum of the graphene quantum dots began to change. Specifically, as the glyphosate concentration increased from 0 μM to 200 μM, the intensity of the 425 nm emission gradually decreased. In contrast, the intensity of the 525 nm emission did not change significantly with the change in glyphosate concentration. Considering that 365 nm excitation light is non-visible light, it can be understood that the higher the glyphosate concentration, the more the overall color of the emitted light observed by the naked eye leans towards green. Based on this characteristic, the concentration range of glyphosate can be roughly determined by visual observation alone, based on the degree to which the overall color of the emitted light leans towards green.

[0043] The intensity of the 365nm excitation light is I 365 The 425nm emission intensity of graphene quantum dots is I. 425 The emitted light intensity at 525nm is I. 525 . Figure 4 Middle I 365 =2000, which is easy to understand. When graphene quantum dots are added to the detection solution, the result is similarly in I... 365 Under the condition of =2000, by only detecting I 425 The value and Figure 4 By comparing the results, the glyphosate concentration can be obtained. However, this detection method is limited to I...365 If changes occur, it cannot be performed, which means that it can only be done through I. 425 Determining glyphosate concentration using numerical values ​​has significant limitations.

[0044] Based on this, this embodiment utilizes the bimodal intensity ratio method to detect glyphosate concentration in graphene quantum dots. The principle of this method is that... 425 and I 525 Will with I 365 Synchronous changes, via I 425 and I 525 The ratio of I to eliminate 365 The effects of the changes, using I 425 and I 525 Determine the glyphosate concentration.

[0045] Specifically, the glyphosate detection method based on the bimodal intensity ratio method provided in this embodiment includes the following steps:

[0046] Step 201: Dissolve graphene quantum dots in the test solution, irradiate with 365nm excitation light, and then detect the intensity of 425nm emission light and 525nm emission light respectively;

[0047] Step 202: Calculate I 425 / I 525 At least based on I 425 / I 525 Determine the glyphosate concentration in the test solution.

[0048] To verify the effectiveness of the above glyphosate detection method, graphene quantum dots and glyphosate of different concentrations were mixed. Specifically, when the glyphosate concentration was 0, I... 425 / I 525 =(I 425 / I 525 0. See also Figure 5 , Figure 5 Corresponding I 365 =2000, it can be clearly seen that as the glyphosate concentration increases, (I 425 / I 525 ) / (I 425 / I 525 The concentration of glyphosate gradually decreased, with the concentration of glyphosate and (I) decreasing when the concentration was below 30 μM. 425 / I 525 ) / (I 425 / I 525 There is a good linear relationship between 0 and 0, and the detection limit is 24 nM. See [link to relevant documentation]. Figure 6 , Figure 6 Corresponding I 365 =1000, and Figure 5 Similarly, as the concentration of glyphosate increases, (I 425 / I 525 ) / (I 425 / I 525 The concentration of glyphosate gradually decreased, with the concentration of glyphosate and (I) decreasing when the concentration was below 30 μM. 425 / I 525 ) / (I 425 / I 525 There is a good linear relationship between I and 0, and the detection limit is 29 nM. Therefore, it can be seen that when the graphene quantum dots provided in this embodiment detect glyphosate concentration based on the bimodal intensity ratio method, the detection limit can be stably below 30 nM, and it does not change with I. 365 The changes produce significant fluctuations.

[0049] See Figure 7 and Figure 8 I 365 When the values ​​are 1000 and 2000 respectively, the expression (I) 425 / I 525 ) / (I 425 / I 525 The two curves corresponding to the relationship between 0 and glyphosate concentration almost completely overlap, indicating that (I) 425 / I 525 ) / (I 425 / I 525 The correlation between 0 and glyphosate concentrations is almost unaffected by I. 365 The impact.

[0050] Based on this, for the corresponding solution to be tested, as long as (I) is detected... 425 / I 525 ) / (I 425 / I 525 After 0, combined with comparison Figure 5 or Figure 6 This allows us to determine the glyphosate concentration.

[0051] See Figure 9 The graphene quantum dots provided in this embodiment were respectively reacted with 100 μM Cd. 2+ Ag + Li + Ba 2+ Co 2+ Fe 3+ Mg 2+ Na + Zn 2+ K + Cl, I -A mixture of acephate, carbendazim, dimethoate, malathion, trichlorfon, paraoxon, and glyphosate shows that only glyphosate can cause (I) 425 / I 525 ) / (I 425 / I 525 The graphene quantum dots provided in this embodiment, combined with the detection method provided in this embodiment, exhibit good detection specificity for glyphosate, thereby ensuring the accuracy of glyphosate detection results.

[0052] Example 2:

[0053] Based on the graphene quantum dots provided in Example 1, this example provides a glyphosate detection device, including a 365nm laser, a nitrocellulose substrate, and a detection element.

[0054] The shape of the detection element is irregular, and its material is the graphene quantum dots provided in Example 1. The nitrocellulose substrate is elongated and extends along a first direction, so that when the test liquid is dropped onto one end of the nitrocellulose substrate, the test liquid can penetrate to the other end of the nitrocellulose substrate based on the concentration difference. The detection element is located in the middle of the nitrocellulose substrate and is attached to the nitrocellulose substrate. During the penetration process, the test liquid can pass through the detection element and react with the graphene quantum dots in the detection element.

[0055] With a 365nm laser pointed towards the test piece, the graphene quantum dots are excited to emit light. Based on the degree of greenness of the emitted light, the tester can visually determine the concentration of glyphosate in the test solution.

[0056] Preferably, the glyphosate detection device also includes a camera terminal, which can be in the form of a mobile phone, tablet, etc. The camera terminal has a camera that, when pointed at the detection object, can capture the emitted light from the object. The camera terminal also has an RGB analysis module to analyze the Ig in the emitted light. 425 / I 525 Then, the concentration of glyphosate was quantitatively measured.

[0057] Preferably, the detection element extends along the second direction, with both ends of the detection element located at the edge of the nitrocellulose substrate. The second direction is inclined relative to the first direction; for example, in this embodiment, the first and second directions are perpendicular.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An application of graphene quantum dots in glyphosate detection, characterized in that, The preparation method of the graphene quantum dots includes the following steps: Tris(hydroxymethyl)aminomethane and resorcinol were mixed and dissolved in water, and then heated in a reaction vessel with a molar ratio of 1:

1. The hydrothermal temperature was 160℃ and the hydrothermal time was not less than 5 hours. The reaction product was centrifuged and filtered, and then the filtrate was dialyzed to obtain graphene quantum dots.

2. The application of graphene quantum dots in glyphosate detection according to claim 1, characterized in that, Each 2 mmol of tris(hydroxymethyl)aminomethane and 2 mmol of resorcinol must be dissolved in at least 20 ml of water.

3. A method for detecting glyphosate, characterized in that, Graphene quantum dots are dissolved in the test solution and then irradiated with 365nm excitation light to obtain 425nm emission light and 525nm emission light. The concentration of glyphosate in the test solution is determined at least based on the intensity ratio between the 425nm emission light and the 525nm emission light. The preparation method of the graphene quantum dots includes the following steps: Tris(hydroxymethyl)aminomethane and resorcinol were mixed and dissolved in water, and then heated in a reaction vessel with a molar ratio of 1:

1. The hydrothermal temperature was 160℃ and the hydrothermal time was not less than 5 hours. The reaction product was centrifuged and filtered, and then the filtrate was dialyzed to obtain graphene quantum dots.

4. The glyphosate detection method according to claim 3, characterized in that, The test solution contains one or more of the following: metal ions, acephate, carbendazim, dimethoate, malathion, trichlorfon, and paraoxon.

Images