CN-118516111-B - Nitrogen-doped carbon dot with high quantum yield, preparation method thereof and method for detecting content of bivalent mercury ions in water

Abstract

The invention relates to a nitrogen-doped carbon dot with high quantum yield, a preparation method thereof and a method for detecting the content of bivalent mercury ions in water, belonging to the technical field of analysis and detection. The nitrogen-doped carbon dot is prepared by taking salicylic acid and nitrilotriacetic acid as raw materials and N, N-dimethylformamide as a solvent through a solvothermal method. Experimental results show that the nitrogen-doped carbon dot has high quantum yield, the quenching fluorescence degree is linearly related to the concentration of Hg 2+ , and the nitrogen-doped carbon dot can be used for quantitative detection of Hg 2+ and has excellent selectivity, anti-interference performance and sensitivity to Hg 2+ . The nitrogen-doped carbon point is combined with a microfluidic platform to be used for detecting the Hg 2+ content in water, and the detection limit can be as low as 0.016 mu M. The microfluidic platform can avoid the use of large instruments, simultaneously reduces reagent loss, and can realize the rapid and convenient detection of Hg 2+ in field water quality.

Inventors

• ZHENG LEI
• LIU HONG
• MA RONGZHEN
• CHANG LIN
• Request for anonymity

Assignees

• 中国科学院重庆绿色智能技术研究院

Dates

Publication Date

20260505

Application Date

20240511

Claims (4)

1. 1. The preparation method is characterized in that salicylic acid and nitrilotriacetic acid are dissolved in N, N-dimethylformamide and then react for 2-10 hours at 140-220 ℃, after the reaction is finished, the mixture is naturally cooled to room temperature, and the mixture is centrifuged, filtered and purified to obtain the nitrogen-doped carbon dot with high quantum yield; The mass ratio of the salicylic acid to the nitrilotriacetic acid is 1:3-3:1, and the ratio of the total mass of the salicylic acid and the nitrilotriacetic acid to the volume of the N, N-dimethylformamide is 2:25-6:25, g/mL.
2. 2. The nitrogen-doped carbon dots with high quantum yield prepared by the preparation method according to claim 1.
3. 3. A method for detecting the content of bivalent mercury ions in water is characterized by comprising the following steps: (1) Respectively introducing the nitrogen-doped carbon point with high quantum yield and deionized water into two liquid inlets of a microfluidic chip, aligning a fluorescent light source to a detection port of the microfluidic chip after the nitrogen-doped carbon point and the deionized water reach the detection port, adjusting the excitation wavelength of the fluorescent light source to 360nm, and measuring the fluorescence intensity F 0 at 406 nm; (2) Respectively introducing the nitrogen-doped carbon dots with high quantum yield and Hg 2+ standard solutions with different concentrations into two liquid inlets of the microfluidic chip, aligning a fluorescent light source to a detection port of the microfluidic chip after the nitrogen-doped carbon dots and the Hg 2+ standard solutions with different concentrations reach the detection port, adjusting the excitation wavelength of the fluorescent light source to 360nm, and respectively measuring the fluorescence intensity F of the nitrogen-doped carbon dots quenched by Hg 2+ with different concentrations at 406 nm; (3) Establishing a linear relation between the fluorescence intensity quenching value F 0 -F of the nitrogen-doped carbon point and the concentration of Hg 2+ standard solution, and drawing a standard curve of the concentration-fluorescence intensity quenching value; (4) The nitrogen-doped carbon point with high quantum yield and the water sample to be detected are respectively introduced into two liquid inlets of the microfluidic chip, after the nitrogen-doped carbon point and the water sample to be detected reach a detection port of the microfluidic chip, a fluorescent light source is aligned to the detection port, the excitation wavelength of the fluorescent light source is regulated to 360nm, the fluorescence intensity F 1 of the nitrogen-doped carbon point quenched by Hg 2+ in the water sample to be detected at 406nm is measured, and then the fluorescence intensity quenching value F 0 －F 1 is substituted into the standard curve in the step (3), so that the content of Hg 2+ in the water sample to be detected can be calculated.
4. 4. The method of claim 3, wherein the channel structure of the microfluidic chip comprises two liquid inlets with the radius of 1mm, more than 1 bending mixing channels, 1 detection port with the radius of 1mm and 1 waste liquid port with the radius of 1mm, wherein the bending mixing channels are positioned in the middle of the two liquid inlets, the length of each bending mixing channel is 2cm, the width of each bending mixing channel is 0.2mm and the distance of each bending mixing channel is 1.8mm, the detection ports are positioned at the lower end of each bending mixing channel, and the waste liquid ports are positioned at the lower end of each detection port.

Description

Nitrogen-doped carbon dot with high quantum yield, preparation method thereof and method for detecting content of bivalent mercury ions in water Technical Field The invention belongs to the technical field of analysis and detection, and relates to a nitrogen-doped carbon dot with high quantum yield, a preparation method thereof and a method for detecting the content of bivalent mercury ions in water. Background Hg 2+ is one of the most common and stable forms of mercury pollution in water, is easily absorbed and accumulated by organisms, can be further transmitted to a human body through a food chain, and can cause damage to the central nervous system and kidneys of the human body when exposed to an environment with excessive mercury ions for a long time, and endangers life when serious. Therefore, the detection of the Hg 2+ content in water is of great importance. The main methods for detecting Hg 2+ content in water at present are an instrumental analysis method, a biological sensing method and a fluorescence sensing method. The instrument analysis method requires expensive and large instruments and equipment and professional detection personnel in the detection process, and the whole detection process is time-consuming and labor-consuming, has obvious data hysteresis, and is difficult to meet the requirements of on-site water quality detection and emergency pre-warning of sudden accidents. In the biological sensing method, stability, consistency and the like of the activity of the biological functional material exist in the detection process, so that the biological sensing method is difficult to adapt to the requirement of long-term monitoring. Compared with the prior art, the fluorescence sensing method realizes the detection of heavy metal ions based on the change of physical and chemical properties such as fluorescence intensity, service life and anisotropy of fluorophor in the fluorescent nano material induced by the target detector, so that the requirements of on-site water quality rapid detection and long-term monitoring can be met. Although the fluorescence sensing method has certain advantages compared with other two detection methods, the fluorescence sensing method has the problems that (1) the fluorescence nano material adopted in the fluorescence sensing method can be selected from carbon points with excellent optical performance, high specific surface area and good biocompatibility, however, the carbon points synthesized by the current method have the defects of weak fluorescence intensity, low quantum yield and the like, and are not beneficial to detection of Hg 2+ content, and (2) the consumption of reagents adopted in the fluorescence sensing method is large, and the detection cost is greatly increased. In order to solve the problems existing in the fluorescence sensing method, it is necessary to develop a new method for synthesizing carbon dots with excellent performance and a new method for detecting Hg 2+ in water based on the carbon dots. Disclosure of Invention In view of the above, it is an object of the present invention to provide a method for preparing nitrogen-doped carbon dots with high quantum yield, another object of the present invention is to provide a nitrogen-doped carbon dot with high quantum yield, and a third object of the present invention is to provide a method for detecting the content of divalent mercury ions in water. In order to achieve the above purpose, the present invention provides the following technical solutions: 1. the preparation method comprises the steps of dissolving salicylic acid and nitrilotriacetic acid in N, N-dimethylformamide, reacting for 2-10 hours at 140-220 ℃, naturally cooling to room temperature after the reaction, centrifuging, filtering and purifying to obtain the nitrogen-doped carbon dot with high quantum yield. Preferably, the mass ratio of the salicylic acid to the nitrilotriacetic acid is 1:3-3:1, and the ratio of the total mass of the salicylic acid and the nitrilotriacetic acid to the volume of the N, N-dimethylformamide is 2:25-6:25, g:mL. 2. The nitrogen-doped carbon dots with high quantum yield are prepared by the preparation method. 3. A method for detecting the content of divalent mercury ions in water, the method comprising the steps of: (1) Respectively introducing the nitrogen-doped carbon point with high quantum yield and deionized water into two liquid inlets of a microfluidic chip, aligning a fluorescent light source to a detection port of the microfluidic chip after the nitrogen-doped carbon point and the deionized water reach the detection port, adjusting the excitation wavelength of the fluorescent light source to 360nm, and measuring the fluorescence intensity F 0 at 406 nm; (2) Respectively introducing the nitrogen-doped carbon point with high quantum yield and Hg 2+ standard solutions with different concentrations into two liquid inlets of the microfluidic chip, aligning a fluorescent light source to a detection