CN114062336B - Method for detecting pesticide weed control intensity based on nitrogen-doped carbon quantum dot fluorescence on-off-on mode - Google Patents

Method for detecting pesticide weed control intensity based on nitrogen-doped carbon quantum dot fluorescence on-off-on mode Download PDF

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CN114062336B
CN114062336B CN202111395000.2A CN202111395000A CN114062336B CN 114062336 B CN114062336 B CN 114062336B CN 202111395000 A CN202111395000 A CN 202111395000A CN 114062336 B CN114062336 B CN 114062336B
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刘梅
马玥
刘沙沙
张晋欣
孙兆萌
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Shaanxi Healthful Biological Engineering Co ltd
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Abstract

The invention discloses a method for detecting pesticide weed killer based on a nitrogen-doped fluorescent carbon quantum dot fluorescence on-off-on mode, which is convenient for synthesis, has good and stable fluorescence characteristic, and comprises the following steps of 3+ Can quench the fluorescence, and the weed killer can be combined with Fe 3+ The specific combination enables quenched fluorescence to be recovered within 1-2 min, so that the method can rapidly and specifically detect the herbicide strength, and can be used for detecting the herbicide strength in fruits, vegetables and water samples.

Description

一种基于氮掺杂碳量子点荧光“开-关-开”模式检测农药杀草 强的方法A fluorescent "on-off-on" mode based on nitrogen-doped carbon quantum dots for the detection of pesticides and herbicides strong method

技术领域technical field

本发明属于有机物检测技术领域,具体涉及一种利用碳量子点荧光“开-关-开”方法检测农药杀草强的方法。The invention belongs to the technical field of organic matter detection, and in particular relates to a method for detecting the pesticide herbicide using a carbon quantum dot fluorescence "on-off-on" method.

背景技术Background technique

杀草强,又名3-氨基-1,2,4-三氮唑,是一种非选择性化学除草剂。由于它在水中的溶解性很强(25℃水中的溶解度是280g/L),在某些条件下,如低有机碳含量和高水位的沙质土壤中,可能会发生淋溶,导致地面和地表水受到污染,并且其挥发性比较差(沸点为245℃),这一特性易造成杀草强在水体中富集,造成水体的严重污染,并通过水为媒介污染植物性食物(水果、蔬菜)。接触过量的杀草强可能造成人类肺泡损伤,甚至造成甲状腺和肝脏肿瘤,从而对环境和人类健康造成了潜在的危害。因此建立一种高选择性、方便快捷的检测农药杀草强的方法意义重大。Herbicide, also known as 3-amino-1,2,4-triazole, is a non-selective chemical herbicide. Due to its strong solubility in water (solubility in water at 25°C is 280g/L), leaching may occur under certain conditions, such as sandy soils with low organic carbon content and high water table, resulting in ground and The surface water is polluted, and its volatility is relatively poor (boiling point is 245°C). This characteristic can easily cause herbicide to accumulate in the water body, causing serious pollution of the water body, and polluting plant foods (fruits, vegetable). Excessive exposure to diaphan may cause alveolar damage in humans, and even cause thyroid and liver tumors, thus causing potential harm to the environment and human health. Therefore, it is of great significance to establish a highly selective, convenient and quick method for detecting the pesticide herbicide.

碳量子点作为一种新型纳米材料,自2004年首次被发现以来,由于其具有的高化学稳定性、良好的导电性和发光性以及良好的生物相容性,引起了人们的广泛关注。碳量子点通常为直径小于10nm的sp2/sp3/sp2-sp3杂化碳质实体的集合,具有特定的量子限制、边缘效应。碳量子点具有单层或多层石墨烯结构,因此通常具有石墨烯晶格,表面常有大量的含氧官能团,现在一般被定义为一类具有碳(主要是sp2)核和表面钝化官能团的核壳型纳米材料。目前各种掺杂剂的应用以及对于碳量子点的表面功能化的研究进展,提升了碳量子点的荧光性能,提高了碳量子点的化学稳定性,使碳量子点具有更广阔的应用前景。As a new type of nanomaterial, carbon quantum dots have attracted widespread attention since they were first discovered in 2004 due to their high chemical stability, good electrical conductivity and luminescence, and good biocompatibility. Carbon quantum dots are usually a collection of sp 2 /sp 3 /sp 2 -sp 3 hybrid carbonaceous entities with diameters less than 10 nm, and have specific quantum confinement and edge effects. Carbon quantum dots have a single-layer or multi-layer graphene structure, so they usually have a graphene lattice and often have a large number of oxygen-containing functional groups on the surface, and are now generally defined as a class with carbon (mainly sp 2 ) nuclei and surface passivation Core-shell nanomaterials with functional groups. At present, the application of various dopants and the research progress on the surface functionalization of carbon quantum dots have improved the fluorescence properties of carbon quantum dots, improved the chemical stability of carbon quantum dots, and made carbon quantum dots have a broader application prospect. .

发明内容Contents of the invention

本发明要解决的问题在于提供利用碳量子点荧光“开-关-开”方法灵敏快速地检测农药杀草强的方法。The problem to be solved by the present invention is to provide a method for sensitively and quickly detecting the pesticide herbicide using the carbon quantum dot fluorescence "on-off-on" method.

解决上述技术问题所采用的技术方案由下述步骤组成:The technical solution adopted to solve the above technical problems consists of the following steps:

1、将氮掺杂荧光碳量子点水溶液和Fe3+溶液依次加入到离心管中,然后用超纯水定容,使所得混合液A中氮掺杂荧光碳量子点的浓度为0.6~1.0μg/mL、Fe3+的浓度为0.015~0.030mmol/L,在340nm激发波长下,记录所得混合液A在430nm处的荧光强度F01. Add nitrogen-doped fluorescent carbon quantum dot aqueous solution and Fe 3+ solution to the centrifuge tube in turn, and then use ultrapure water to make up the volume, so that the concentration of nitrogen-doped fluorescent carbon quantum dots in the obtained mixture A is 0.6-1.0 The concentration of μg/mL and Fe 3+ is 0.015-0.030 mmol/L, and the fluorescence intensity F 0 of the obtained mixture A at 430 nm is recorded at an excitation wavelength of 340 nm.

2、将氮掺杂荧光碳量子点水溶液和Fe3+溶液依次加入到离心管中,并加入杀草强标准溶液,然后用超纯水定容,使所得混合液B中氮掺杂荧光碳量子点和Fe3+的浓度与步骤1相同,混合液B震荡1~2min后在340nm激发波长下,记录所得混合液B在430nm处加入不同浓度的杀草强标准溶液的荧光强度F,以F-F0为纵坐标,杀草强的加入浓度为横坐标,绘制荧光强度随杀草强浓度变化的标准曲线。2. Add the nitrogen-doped fluorescent carbon quantum dot aqueous solution and the Fe 3+ solution to the centrifuge tube in turn, and add the dibasin standard solution, and then use ultrapure water to make the nitrogen-doped fluorescent carbon in the obtained mixed solution B The concentration of quantum dots and Fe 3+ is the same as in step 1. After the mixed solution B is shaken for 1 to 2 minutes, under the excitation wavelength of 340nm, record the fluorescence intensity F of the mixed solution B added with different concentrations of dichlorpyr standard solution at 430nm, to FF 0 is the ordinate, and the added concentration of herbicide is the abscissa, and the standard curve of the fluorescence intensity changing with the concentration of herbicide is drawn.

3、按照步骤2的方法测试加入待测杀草强样品时,在340nm激发波长下、430nm处的荧光强度,对照步骤2中标准曲线的线性方程即可计算出待测杀草强样品中杀草强的浓度。3. According to the method of step 2, when adding the herbicide sample to be tested, the fluorescence intensity at 430nm under the excitation wavelength of 340nm can be calculated according to the linear equation of the standard curve in step 2. Strong concentration of grass.

上述氮掺杂荧光碳量子点的合成方法为:将柠檬酸和尿素按质量比为1:1加入超纯水中,混合均匀后加入特氟龙高压反应釜,将特氟龙高压反应釜放入烘箱中,180℃保持1h后自然冷却至室温,得到氮掺杂荧光碳量子点粗溶液,反应得到的溶液加入1kw透析袋,透析液为超纯水,透析8~12h除去小分子杂质,后收集透析液冷冻干燥12~16h,得到蓝色的氮掺杂荧光碳量子点粉末,置于4℃冰箱保存。The synthesis method of the above-mentioned nitrogen-doped fluorescent carbon quantum dots is as follows: citric acid and urea are added into ultrapure water at a mass ratio of 1:1, mixed evenly, then added to a Teflon autoclave, and the Teflon autoclave is placed Put it into an oven, keep it at 180°C for 1 hour, and then cool it down to room temperature naturally to obtain a crude solution of nitrogen-doped fluorescent carbon quantum dots. The solution obtained from the reaction is added to a 1kw dialysis bag, and the dialysate is ultrapure water. Afterwards, the dialysate was collected and freeze-dried for 12-16 hours to obtain blue nitrogen-doped fluorescent carbon quantum dot powder, which was stored in a refrigerator at 4°C.

上述Fe3+溶液为分析纯FeCl3水溶液。The above-mentioned Fe 3+ solution is an analytically pure FeCl 3 aqueous solution.

上述杀草强标准溶液为杀草强的水溶液。The above-mentioned herbicide standard solution is the aqueous solution of herbicide.

上述待测杀草强样品为果蔬或水样。其中,待测杀草强样品为果蔬时,检测前先将果蔬加入二氯甲烷与体积浓度1%的乙酸水溶液体积比为1:1的混合液中,优选控制混合液中果蔬的加入量为20~30g/100mL,粉碎均质后离心分离,弃去下层二氯甲烷层,取上层清液用0.22μm微滤膜过滤,所得滤液作为待测杀草强样品。The above-mentioned herbicidal samples to be tested are fruit and vegetable or water samples. Wherein, when the herbicide samples to be tested are fruits and vegetables, before the detection, the fruits and vegetables are added to the mixed solution of dichloromethane and acetic acid aqueous solution with a volume concentration of 1% in a volume ratio of 1:1, preferably the amount of fruits and vegetables in the mixed solution is controlled to 20-30g/100mL, pulverized and homogeneous, centrifuged, discarded the lower dichloromethane layer, took the supernatant and filtered it with a 0.22μm microfiltration membrane, and the obtained filtrate was used as the dichloromethane sample to be tested.

本发明的有益效果如下:The beneficial effects of the present invention are as follows:

本发明的氮掺杂荧光碳量子点通过一步水热法合成,合成方便,具有良好的荧光特性和水稳定性,Fe3+能够猝灭其荧光,杀草强能够与Fe3+特异性结合使得被猝灭的荧光在1~2min内恢复,因此本方法能够快速、专一地检测杀草强,可用于检测果蔬及水样中的杀草强。The nitrogen-doped fluorescent carbon quantum dot of the present invention is synthesized by a one-step hydrothermal method, which is convenient to synthesize, has good fluorescence characteristics and water stability, and Fe 3+ can quench its fluorescence, and dioxadon can specifically combine with Fe 3+ The quenched fluorescence recovers within 1-2 minutes, so the method can quickly and specifically detect the herbicide, and can be used to detect the herbicide in fruits, vegetables and water samples.

附图说明Description of drawings

图1是氮掺杂荧光碳量子点的紫外可见吸收光谱图。Fig. 1 is an ultraviolet-visible absorption spectrum diagram of nitrogen-doped fluorescent carbon quantum dots.

图2是不同激发波长下氮掺杂荧光碳量子点的荧光光谱图。Fig. 2 is a graph of fluorescence spectra of nitrogen-doped fluorescent carbon quantum dots at different excitation wavelengths.

图3是氮掺杂荧光碳量子点的透射电镜以及高分辨率透射电镜图。Fig. 3 is a transmission electron microscope and a high-resolution transmission electron microscope image of nitrogen-doped fluorescent carbon quantum dots.

图4是氮掺杂荧光碳量子点的粒径分布图。Fig. 4 is a particle size distribution diagram of nitrogen-doped fluorescent carbon quantum dots.

图5是氮掺杂荧光碳量子点的X射线衍射图谱。Fig. 5 is an X-ray diffraction pattern of nitrogen-doped fluorescent carbon quantum dots.

图6是氮掺杂荧光碳量子点的X射线光电子能谱。Fig. 6 is the X-ray photoelectron spectrum of nitrogen-doped fluorescent carbon quantum dots.

图7是氮掺杂荧光碳量子点的傅里叶红外光谱。Figure 7 is the Fourier infrared spectrum of nitrogen-doped fluorescent carbon quantum dots.

图8是不同浓度的杀草强存在下Fe3+与氮掺杂荧光碳量子点混合溶液的荧光光谱图。Fig. 8 is a fluorescence spectrum diagram of a mixed solution of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots in the presence of different concentrations of dimethadone.

图9是Fe3+与氮掺杂荧光碳量子点混合溶液在430nm处的荧光强度随杀草强浓度变化的线性关系图。Fig. 9 is a linear relationship diagram of the fluorescence intensity at 430nm of a mixed solution of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots as a function of the concentration of herbicide.

图10是Fe3+与氮掺杂荧光碳量子点混合溶液对杀草强识别的抗干扰性能。Figure 10 shows the anti-interference performance of the mixed solution of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots on the recognition of herbicide.

具体实施方式Detailed ways

下面结合附图和实施例对本发明进一步详细说明,但本发明的保护范围不仅限于这些实施例。The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

实施例1Example 1

1、将2g柠檬酸、2g尿素加入20mL超纯水中,混合均匀后加入特氟龙高压反应釜,将特氟龙高压反应釜放入烘箱中,180℃水热合成1h,得到的深松石绿色的荧光碳量子点溶液用1kw透析袋,透析12h后冷冻干燥,得到蓝色的氮掺杂荧光碳量子点粉末。由图1可见,所得氮掺杂荧光碳量子点的紫外可见吸收光谱在238nm处观察到一个吸收峰,该峰是由于氧化芳香族结构的C=C键的π-π*跃迁,332nm处的吸收带是由于表面羧基、氨基和其他使表面陷阱钝化的基团所致。当激发波长从310nm变化到370nm时,氮掺杂荧光碳量子点的荧光强度在340nm处达到最大值,然后进一步下降,但发射峰位在430nm处,几乎不随激发波长变化而变化(见图2),表现出与激发无关的光致发光特征,这一特征与已报道的碳量子点相同。由图3所可见,所得氮掺杂荧光碳量子点是具有良好分散性的球形颗粒,其粒径范围在4~13nm之间,平均粒径为8nm(见图4),高分辨率图像显示其具有0.32nm的晶格间距,这也应证了氮掺杂荧光碳量子点的X射线衍射图谱(图5)。如图5所示,在11.7°和27.3°处有两个峰,分别对应于晶格间距0.75nm和0.32nm,2θ=11.7°处的较弱一点的峰是由于具有氧化石墨的晶格间距,表明氮掺杂荧光碳量子点在合成过程中部分被氧化;在2θ=27.3°处的尖锐的高强度反射较为接近石墨烯的晶格间距0.34nm,这说明生成的氮掺杂荧光碳量子点具有石墨烯结构并且证明了氮掺杂荧光碳量子点的成功合成。采用X射线光电子能谱能分析合成的氮掺杂荧光碳量子点中的元素组成和化学键类型。如图6所示,在284.6、399.0和531.6eV处有三个主要的峰分别对应于C1s、N1s和O1s,表明通过水热处理成功地将氮原子掺入了碳量子点的构架中。根据碳、氮和氧的峰值强度,得出氮的掺杂浓度约为12.1%。C1s的高分辨率光谱展现出三个主要峰,其中位于284.6eV的最强峰对应于碳原子的sp2共轭二维骨架结构,而另外两个位于288.19eV和286.10eV的峰分归因于C=O键和C-O/C-N键。N1s的高分辨率光谱表明氮元素的杂化方式主要表现为吡咯型氮和石墨氮。此外,还用傅里叶红外光谱对氮掺杂碳量子点进行了官能团表征(见图7),光谱显示在3150cm-1、1700cm-1、1584cm-1和1399cm-1处有4个较强的峰,分别代表-OH的伸缩振动、C=O的伸缩振动、N-H的伸缩振动、C-O-C的弯曲振动,说明氮掺杂荧光碳量子点表面存在大量的氨基、羟基和羧基,这使得氮掺杂碳量子点具有成为亲水性良好的荧光探针的潜力。1. Add 2g of citric acid and 2g of urea into 20mL of ultra-pure water, mix well and add into a Teflon high-pressure reactor, put the Teflon high-pressure reactor into an oven, and perform hydrothermal synthesis at 180°C for 1 hour to obtain deep turquoise The green fluorescent carbon quantum dot solution was dialyzed with a 1kw dialysis bag for 12 hours and then freeze-dried to obtain blue nitrogen-doped fluorescent carbon quantum dot powder. As can be seen from Figure 1, an absorption peak is observed at 238nm in the UV-Vis absorption spectrum of the resulting nitrogen-doped fluorescent carbon quantum dots, which is due to the π-π* transition of the C=C bond of the oxidized aromatic structure, and the π-π* transition at 332nm The absorption bands are due to surface carboxyl groups, amino groups, and other groups that passivate surface traps. When the excitation wavelength changes from 310nm to 370nm, the fluorescence intensity of nitrogen-doped fluorescent carbon quantum dots reaches a maximum at 340nm, and then further decreases, but the emission peak is at 430nm, which hardly changes with the excitation wavelength (see Figure 2 ), exhibiting an excitation-independent photoluminescence signature, which is the same as that reported for carbon quantum dots. As can be seen from Figure 3, the obtained nitrogen-doped fluorescent carbon quantum dots are spherical particles with good dispersion, the particle size range is between 4 and 13nm, and the average particle size is 8nm (see Figure 4), and the high-resolution image shows It has a lattice spacing of 0.32 nm, which also confirms the X-ray diffraction pattern of nitrogen-doped fluorescent carbon quantum dots ( FIG. 5 ). As shown in Figure 5, there are two peaks at 11.7° and 27.3°, corresponding to the lattice spacing of 0.75nm and 0.32nm, respectively, and the weaker peak at 2θ=11.7° is due to the lattice spacing of graphite oxide , indicating that nitrogen-doped fluorescent carbon quantum dots were partially oxidized during the synthesis process; the sharp high-intensity reflection at 2θ=27.3° is closer to the lattice spacing of graphene 0.34nm, which indicates that the generated nitrogen-doped fluorescent carbon quantum dots The dots have a graphene structure and demonstrate the successful synthesis of nitrogen-doped fluorescent carbon quantum dots. X-ray photoelectron spectroscopy was used to analyze the elemental composition and chemical bond types in the synthesized nitrogen-doped fluorescent carbon quantum dots. As shown in Figure 6, there are three main peaks at 284.6, 399.0, and 531.6 eV corresponding to C1s, N1s, and O1s, respectively, indicating that nitrogen atoms were successfully incorporated into the framework of carbon quantum dots by hydrothermal treatment. According to the peak intensities of carbon, nitrogen and oxygen, the doping concentration of nitrogen is about 12.1%. The high-resolution spectrum of C1s exhibits three main peaks, among which the strongest peak at 284.6eV corresponds to the sp conjugated two-dimensional framework structure of carbon atoms, while the other two peaks at 288.19eV and 286.10eV are attributed to In C=O bond and CO/CN bond. The high-resolution spectrum of N1s shows that the hybridization mode of nitrogen element is mainly pyrrole nitrogen and graphitic nitrogen. In addition, the functional groups of nitrogen- doped carbon quantum dots were characterized by Fourier transform infrared spectroscopy (see Figure 7), and the spectra showed that there were four strong The peaks represent the stretching vibration of -OH, the stretching vibration of C=O, the stretching vibration of NH, and the bending vibration of COC, indicating that there are a large number of amino groups, hydroxyl groups and carboxyl groups on the surface of nitrogen-doped fluorescent carbon quantum dots, which makes nitrogen-doped Heterocarbon quantum dots have the potential to become fluorescent probes with good hydrophilicity.

将上述氮掺杂荧光碳量子点粉末加入超纯水,配制成3μg/mL氮掺杂荧光碳量子点溶液;将100μL 3μg/mL荧光碳量子点溶液和100μL 0.1mmol/L的FeCl3水溶液依次加入到1.5mL离心管中,然后用超纯水调节总体积至400μL,在340nm激发波长下,记录在430nm处的荧光强度F0Add the above-mentioned nitrogen-doped fluorescent carbon quantum dot powder into ultrapure water to prepare a 3 μg/mL nitrogen-doped fluorescent carbon quantum dot solution; add 100 μL 3 μg/mL fluorescent carbon quantum dot solution and 100 μL 0.1 mmol/L FeCl3 aqueous solution Add it into a 1.5mL centrifuge tube, then adjust the total volume to 400μL with ultrapure water, and record the fluorescence intensity F 0 at 430nm at an excitation wavelength of 340nm.

2、向1.5mL离心管中依次加入100μL 3μg/mL氮掺杂荧光碳量子点溶液、100μL0.1mmol/L的FeCl3水溶液和200μL浓度分别为0.5、1、5、10、15、20、25、30、35、40、50、60、80、100μg/mL的杀草强水溶液,总体积为400μL,混合溶液震荡1min后在340nm激发波长下,记录在430nm处加入不同浓度的杀草强的荧光强度F,以F-F0为纵坐标,杀草强的加入浓度为横坐标,绘制荧光强度随杀草强浓度变化的标准曲线。2. Add 100 μL of 3 μg/mL nitrogen-doped fluorescent carbon quantum dot solution, 100 μL of 0.1 mmol/L FeCl 3 aqueous solution and 200 μL of 0.5, 1, 5, 10, 15, 20, 25 respectively into a 1.5 mL centrifuge tube , 30, 35, 40, 50, 60, 80, and 100 μg/mL of herbicide aqueous solutions, with a total volume of 400 μL. After the mixed solution was shaken for 1 min, at the excitation wavelength of 340 nm, it was recorded at 430 nm where different concentrations of herbicide were added. Fluorescence intensity F, with FF 0 as the ordinate, and the concentration of phytoxadin as the abscissa, draw the standard curve of the fluorescence intensity changing with the concentration of phytoxadin.

由图8可见,加入不同浓度的杀草强后的Fe3+与氮掺荧光杂碳量子点混合溶液体系的荧光光强度随着杀草强的浓度增大而升高没有红移或蓝移,说明杀草强可以有效地恢复Fe3+与氮掺杂荧光碳量子点混合溶液体系的荧光。由图9可见,该体系的荧光强度随着体系中杀草强浓度的增大变化很明显,说明Fe3+与荧光碳量子点混合溶液体系对杀草强的检测灵敏度很高。构建检测杀草强的标准曲线,其中杀草强浓度为0~40μg/mL时,荧光强度差值与杀草强浓度呈线性关系,相关系数为0.9996,线性方程为:y=19.77318x–2.9781,式中y为荧光强度差值(F-F0),x为杀草强的加入浓度。由图9可见,F-F0与杀草强浓度的线性关系很好。利用最低检测限的公式计算最低检测限,检出限(LOD=3s/K,s为空白的标准偏差,K为线性方程的斜率)为0.183μg/mL(约0.183mg/kg),低于国家标准中规定的水果中的限量0.5mg/kg。It can be seen from Figure 8 that the fluorescence light intensity of the mixed solution system of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots after adding different concentrations of dichlorpyr increases without red shift or blue shift , indicating that dichlorpyr can effectively restore the fluorescence of the mixed solution system of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots. It can be seen from Fig. 9 that the fluorescence intensity of the system changes significantly with the increase of the concentration of webicide in the system, indicating that the mixed solution system of Fe 3+ and fluorescent carbon quantum dots has a high detection sensitivity to webicide. Construct a standard curve for the detection of herbicide, where when the concentration of herbicide is 0-40 μg/mL, the difference between the fluorescence intensity and the concentration of herbicide is linear, the correlation coefficient is 0.9996, and the linear equation is: y=19.77318x–2.9781 , where y is the fluorescence intensity difference (FF 0 ), and x is the added concentration of dibasin. It can be seen from Figure 9 that the linear relationship between FF 0 and the concentration of herbicide is very good. Utilize the formula of the minimum detection limit to calculate the minimum detection limit, the detection limit (LOD=3s/K, s is the standard deviation of the blank, K is the slope of the linear equation) is 0.183 μ g/mL (about 0.183 mg/kg), lower than The limit in fruit stipulated in the national standard is 0.5mg/kg.

3、称取5g待测水果于50mL离心管中,加入10mL二氯甲烷和10mL体积浓度为1%的乙酸水溶液,粉碎均质后在5000r/min转速下离心15min,弃去下层二氯甲烷层,取上层清液5mL,用0.22μm微滤膜过滤,所得滤液作为待测杀草强样品。按照步骤2的方法测试加入待测杀草强样品时,在340nm激发波长下、430nm处的荧光强度,对照步骤2中标准曲线的线性方程即可计算出待测杀草强样品中杀草强的浓度。3. Weigh 5g of the fruit to be tested in a 50mL centrifuge tube, add 10mL of dichloromethane and 10mL of acetic acid aqueous solution with a volume concentration of 1%, crush and homogenize, and centrifuge at 5000r/min for 15min, discard the lower dichloromethane layer , take 5 mL of the supernatant, filter it with a 0.22 μm microfiltration membrane, and the obtained filtrate is used as a sample of dibasin to be tested. According to the method of step 2, when adding the herbicide sample to be tested, under the excitation wavelength of 340nm, the fluorescence intensity at 430nm can be calculated according to the linear equation of the standard curve in step 2. concentration.

为了证明本发明的有益效果,将Fe3+与氮掺杂荧光碳量子点混合溶液体系对于杀草强的选择性进行测试,试验情况如下:In order to prove the beneficial effects of the present invention, Fe3 + and nitrogen-doped fluorescent carbon quantum dot mixed solution system are tested for the selectivity of herbicide, and the test conditions are as follows:

向1.5mL离心管中依次加入100μL 3μg/mL氮掺杂荧光碳量子点溶液、100μL0.1mmol/L的FeCl3水溶液、200μL浓度为20μg/mL的杀草强水溶液或200μL 1mmol/L的干扰离子(如K+、Na+、Ca2+、Mg2+、Fe2+、Cu2+、SO4 2-、Cl-和HPO4 2-,干扰离子的量是铁离子量的10倍)或200μL 100μg/mL其他农药(如代森锰锌、辛硫磷、氯氰菊酯,其他农药的量是杀草强的5倍),总体积为400μL,混合溶液震荡1min后在340nm激发波长下,记录在430nm处加入不同干扰离子和农药的荧光强度。Add 100 μL of 3 μg/mL nitrogen-doped fluorescent carbon quantum dot solution, 100 μL of 0.1 mmol/L FeCl 3 aqueous solution, 200 μL of 20 μg/mL aqueous solution of dibasin or 200 μL of 1 mmol/L interfering ions into a 1.5 mL centrifuge tube or _ _ _ _ _ _ _ _ _ _ 200 μL of 100 μg/mL other pesticides (such as mancozeb, phoxim, cypermethrin, the amount of other pesticides is 5 times that of herbicide), the total volume is 400 μL, and the mixed solution is shaken for 1 min at an excitation wavelength of 340 nm, and recorded at Fluorescence intensity of different interfering ions and pesticides added at 430nm.

如图10所示,只有杀草强存在时,Fe3+与氮掺杂荧光碳量子点混合溶液体系的荧光强度明显恢复。所有其他农药、干扰离子均不和Fe3+与氮掺杂荧光碳量子点混合溶液体系反应。这些结果表明,其他离子和其他农药对体系的荧光值的干扰很小,说明猝灭的Fe3+与氮掺杂荧光碳量子点混合溶液体系对目标物杀草强的检测具有很高的选择性。As shown in Figure 10, the fluorescence intensity of the mixed solution system of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots is obviously restored when only dichlorpyr exists. All other pesticides and interfering ions do not react with the mixed solution system of Fe 3+ and nitrogen-doped fluorescent carbon quantum dots. These results show that other ions and other pesticides have little interference on the fluorescence value of the system, indicating that the mixed solution system of quenched Fe 3+ and nitrogen-doped fluorescent carbon quantum dots has a high selectivity for the detection of the target herbicide sex.

Claims (7)

1.一种基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于:1. A method for detecting pesticide herbicide based on nitrogen-doped fluorescent carbon quantum dot fluorescence "on-off-on" mode, characterized in that: (1)将氮掺杂荧光碳量子点水溶液和Fe3+溶液依次加入到离心管中,然后用超纯水定容,使所得混合液A中氮掺杂荧光碳量子点的浓度为0.6~1.0μg/mL、Fe3+的浓度为0.015~0.030mmol/L,在340nm激发波长下,记录所得混合液A在430nm处的荧光强度F0(1) Nitrogen-doped fluorescent carbon quantum dot aqueous solution and Fe 3+ solution are added in the centrifuge tube successively, then constant volume with ultrapure water, make the concentration of nitrogen-doped fluorescent carbon quantum dot in the obtained mixed solution A be 0.6~ 1.0 μg/mL, the concentration of Fe 3+ is 0.015 ~ 0.030mmol/L, under the excitation wavelength of 340nm, record the fluorescence intensity F 0 of the obtained mixture A at 430nm; (2)将氮掺杂荧光碳量子点水溶液和Fe3+溶液依次加入到离心管中,并加入杀草强标准溶液,然后用超纯水定容,使所得混合液B中氮掺杂荧光碳量子点和Fe3+的浓度与步骤(1)相同,混合液B震荡1~2min后在340nm激发波长下,记录所得混合液B在430nm处加入不同浓度的杀草强标准溶液的荧光强度F,以F-F0为纵坐标,杀草强的加入浓度为横坐标,绘制荧光强度随杀草强浓度变化的标准曲线;(2) Add nitrogen-doped fluorescent carbon quantum dot aqueous solution and Fe 3+ solution to the centrifuge tube successively, and add dichlorpyr standard solution, then use ultrapure water to constant volume, make the nitrogen-doped fluorescence in the obtained mixed solution B The concentration of carbon quantum dots and Fe 3+ is the same as in step (1). After the mixed solution B is shaken for 1 to 2 minutes, under the excitation wavelength of 340nm, record the fluorescence intensity of the obtained mixed solution B at 430nm by adding different concentrations of dichlorpyr standard solution F, with FF 0 as the ordinate, and the addition concentration of herbicide as the abscissa, draw the standard curve that the fluorescence intensity varies with the concentration of herbicide; (3)按照步骤(2)的方法测试加入待测杀草强样品时,在340nm激发波长下、430nm处的荧光强度,对照步骤(2)中标准曲线的线性方程即可计算出待测杀草强样品中杀草强的浓度。(3) according to the method test of step (2) when adding the herbicide to be tested sample, under the excitation wavelength of 340nm, the fluorescence intensity at 430nm, the linear equation of the standard curve in the contrast step (2) can calculate the to-be-tested herbicide The concentration of herbicide in the grass strength sample. 2.根据权利要求1所述的基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于所述氮掺杂荧光碳量子点的合成方法为:将柠檬酸和尿素按质量比为1:1加入超纯水中,混合均匀后加入特氟龙高压反应釜,将特氟龙高压反应釜放入烘箱中,180℃保持1h后自然冷却至室温,得到氮掺杂荧光碳量子点粗溶液,反应得到的溶液加入1kw透析袋,透析液为超纯水,透析8~12h除去小分子杂质,后收集透析液冷冻干燥12~16h,得到蓝色的氮掺杂荧光碳量子点粉末,置于4℃冰箱保存。2. the method for detecting pesticide herbicide based on nitrogen-doped fluorescent carbon quantum dot fluorescence "on-off-open" mode according to claim 1, characterized in that the synthesis method of said nitrogen-doped fluorescent carbon quantum dot is : Add citric acid and urea into ultrapure water at a mass ratio of 1:1, mix well and then add the Teflon autoclave, put the Teflon autoclave in an oven, keep at 180°C for 1 hour, and then cool naturally to At room temperature, a crude solution of nitrogen-doped fluorescent carbon quantum dots was obtained, and the solution obtained from the reaction was added to a 1kw dialysis bag, the dialysate was ultrapure water, and the small molecule impurities were removed by dialysis for 8-12 hours, and then the dialysate was collected and freeze-dried for 12-16 hours to obtain blue The colored nitrogen-doped fluorescent carbon quantum dot powder was stored in a refrigerator at 4°C. 3.根据权利要求1所述的基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于:所述Fe3+溶液为分析纯FeCl3水溶液。3. the method for detecting the pesticide herbicide based on nitrogen-doped fluorescent carbon quantum dot fluorescence "on-off-on" mode according to claim 1, characterized in that: the Fe solution is analytically pure FeCl aqueous solution . 4.根据权利要求1所述的基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于:所述杀草强标准溶液为杀草强的水溶液。4. The method according to claim 1 based on the fluorescence "on-off-on" mode of nitrogen-doped fluorescent carbon quantum dots to detect the method of pesticide abicide, characterized in that: said abicide standard solution is a diazepam aqueous solution. 5.根据权利要求1所述的基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于:所述待测杀草强样品为果蔬或水样。5. The method for detecting the pesticide herbicide based on nitrogen-doped fluorescent carbon quantum dot fluorescence "on-off-on" mode according to claim 1, characterized in that: the sample of herbicide to be tested is fruit, vegetable or water Sample. 6.根据权利要求5所述的基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于:所述待测杀草强样品为果蔬时,检测前先将果蔬加入二氯甲烷与体积浓度1%的乙酸水溶液体积比为1:1的混合液中,粉碎均质后离心分离,弃去下层二氯甲烷层,取上层清液用0.22μm微滤膜过滤,所得滤液作为待测杀草强样品。6. The method for detecting the pesticide herbicide based on nitrogen-doped fluorescent carbon quantum dot fluorescence "on-off-on" mode according to claim 5, characterized in that: when the sample of herbicide to be tested is a fruit or vegetable, Before the test, add the fruits and vegetables to the mixture of dichloromethane and 1% acetic acid aqueous solution with a volume ratio of 1:1, crush and homogenize, then centrifuge, discard the lower dichloromethane layer, and take the supernatant with 0.22 μm Microfiltration membrane filtration, the obtained filtrate is used as the sample of dibasin to be tested. 7.根据权利要求6所述的基于氮掺杂荧光碳量子点荧光“开-关-开”模式检测农药杀草强的方法,其特征在于:将果蔬加入二氯甲烷与体积浓度1%的乙酸水溶液体积比为1:1的混合液中,控制混合液中果蔬的加入量为20~30g/100mL。7. The method for detecting the pesticide herbicide based on nitrogen-doped fluorescent carbon quantum dot fluorescence "on-off-on" mode according to claim 6, characterized in that: adding dichloromethane and 1% volume concentration of fruits and vegetables In the mixed solution whose volume ratio of acetic acid aqueous solution is 1:1, the amount of fruits and vegetables added in the mixed solution is controlled to be 20-30g/100mL.
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