CN-122016741-A - Method for detecting coumaphos based on carbon quantum dot-ferric ion solution system

CN122016741ACN 122016741 ACN122016741 ACN 122016741ACN-122016741-A

Abstract

The invention discloses a method for detecting coumaphos based on a carbon quantum dot-ferric ion solution system, which comprises the steps of dissolving lotus seed powder in deionized water, carrying out ultrasonic treatment until solid is completely dissolved, adding a passivating agent, uniformly mixing to obtain uniform solution, carrying out pyrolysis reaction on the uniform solution, naturally cooling to obtain brown solution, centrifuging the obtained dark brown solution to remove large-particle precipitates, carrying out suction filtration on the obtained dark brown solution by using a filter membrane with the pore diameter of 0.22 mu m to obtain a carbon quantum dot solution, carrying out rotary evaporation on the obtained carbon quantum dot solution to obtain a concentrated solution, and finally carrying out freeze drying on the concentrated solution to obtain powdery carbon quantum dots. The blue luminescent carbon quantum dot synthesized by the invention realizes the fluorescent 'off-on' integrated detection of iron ion quenching-coumaphos recovery for the first time, can rapidly and sensitively detect coumaphos on site, realizes quantitative analysis, and expands the application of the fluorescent carbon quantum dot in the field of pesticide residue detection.

Inventors

ZHANG DIE
DONG PING
ZHAO CHEN
HU YUJIA
LI MENGHAN

Assignees

河南医药大学

Dates

Publication Date: 20260512
Application Date: 20260107

Claims (6)

1. The method for detecting coumaphos based on the carbon quantum dot-iron ion solution system is characterized by comprising the following specific steps: The preparation method comprises the steps of S1, preparing the carbon quantum dots by taking biomass lotus seed powder and a passivating agent as raw materials and performing hydrothermal reaction at 60-220 ℃, wherein the passivating agent is one or more of diethylamine, ethanolamine, polyethyleneimine or polyethylene glycol; Step S2, drawing a standard curve, namely respectively adding 0.50mL of Tris-HCl buffer solution with pH of 7.4, 4 mu L of carbon quantum dot solution with 6.12mg/mL and 35 mu L of iron ion solution with 5mg/mL into a series of centrifuge tubes, sequentially adding coumaphos standard solution with increasing concentration, fixing the volume to 4.00mL by using ultrapure water, shaking uniformly, scanning fluorescence emission spectrum with 350nm as excitation wavelength, recording fluorescence intensity at 435nm of emission wavelength, recording fluorescence intensity at 435nm of the uncomforted coumaphos standard solution in the mixed system as F1, adding fluorescence intensity at 435nm of coumaphos standard solution as F2, calculating F2-F1 value, and obtaining a linear regression equation as Q=293.17+10.25× (F2-F1), wherein Q is coumaphos concentration, the linear range is 12.5-150 mu g/L, the detection limit is 1.55 mu g/L, and the quantitative limit is 5.15 mu g/L; And S3, detecting the concentration of the coumaphos in the coumaphos-containing solution to be detected, namely adding 0.50mL of Tris-HCl buffer solution with pH=7.4, 4 mu L of carbon quantum dot solution with 6.12mg/mL and 35 mu L of iron ion solution with 5mg/mL into a centrifuge tube, adding the coumaphos-containing solution to be detected, fixing the volume to 4.00mL by using ultrapure water, shaking uniformly, scanning the fluorescence emission spectrum by using 350nm as an excitation wavelength, recording the fluorescence intensity at 435nm of the emission wavelength, marking the fluorescence intensity at 435nm of the solution to be detected without coumaphos-containing solution to be detected as F1, adding the fluorescence intensity at 435nm of the emission wavelength of the coumaphos-containing solution to be detected as F2, calculating the value of F2-F1, and calculating the coumaphos concentration in the coumaphos-containing solution to be detected based on a linear regression equation.
2. The method for detecting coumaphos based on the carbon quantum dot-ferric ion solution system of claim 1, wherein the carbon quantum dot-ferric ion solution system formed by the carbon quantum dot and the ferric ion can selectively detect coumaphos in an interfering object, and the interfering object is one or more of azoxystrobin, dichlorvos, fungicide, methidathion, imidacloprid, carbofuran, phoxim, beclomethasone, isoprocarb, parathion, iminothiophos, aquafos, procymidone, terbuthion, trichlorfon, carbendazim or methyl parathion.
3. The method for detecting coumaphos based on the carbon quantum dot-iron ion solution system is characterized in that the specific preparation process of the carbon quantum dot is that biomass lotus seed powder is dissolved in deionized water and is subjected to ultrasonic treatment until solids are completely dissolved, then a passivating agent is added and is uniformly mixed to obtain a uniform solution, the uniform solution is transferred into a hydrothermal reaction kettle to be subjected to pyrolysis reaction at 60-220 ℃ for 2-8 hours, natural cooling is carried out after the reaction is finished to obtain a brown solution, the obtained dark brown solution is centrifuged to remove large particle precipitates, a filter membrane with the aperture of 0.22 mu m is used for carrying out suction filtration to obtain a carbon quantum dot solution, the obtained carbon quantum dot solution is subjected to rotary evaporation to obtain a concentrated solution, and finally the concentrated solution is subjected to freeze drying to obtain powdery carbon quantum dots.
4. The method for detecting coumaphos based on the carbon quantum dot-ferric ion solution system, which is characterized in that the mixture ratio of lotus seed powder, deionized water and passivating agent is 0.3 g:9-10 mL:0.2-0.8 mL.
5. The method for detecting coumaphos based on the carbon quantum dot-ferric ion solution system according to claim 3, wherein the freeze-drying temperature is-50 ℃.
6. The method for detecting coumaphos based on the carbon quantum dot-iron ion solution system is characterized by comprising the specific preparation steps of dissolving 0.3g of biomass lotus seed powder in 10mL of deionized water, carrying out ultrasonic treatment until solids are completely dissolved, adding 0.8mL of passivating agent ethanolamine, uniformly mixing to obtain a uniform solution, transferring the uniform solution into a hydrothermal reaction kettle, carrying out pyrolysis reaction at 200 ℃ for 4 hours, naturally cooling after the reaction is finished, centrifuging the obtained dark brown solution to remove large-particle precipitates, carrying out suction filtration on the obtained solution by using a filter membrane with the pore diameter of 0.22 mu m to obtain a carbon quantum dot solution, carrying out rotary evaporation on the obtained carbon quantum dot solution to obtain a concentrated solution, and finally carrying out freeze drying on the concentrated solution at-50 ℃ to obtain powdery carbon quantum dots.

Description

Method for detecting coumaphos based on carbon quantum dot-ferric ion solution system Technical Field The invention belongs to the technical field of synthesis of carbon nano materials and pesticide residue detection of coumaphos, and particularly relates to a method for detecting coumaphos based on a carbon quantum dot-iron ion solution system. Background Among many pesticides, coumaphos is used as a highly toxic organophosphorus insecticide and anti-mite agent, and is extremely easy to remain and accumulate in agricultural products due to its strong chemical stability and difficulty in degradation. The national standard of China (GB 2763-2021) strictly prescribes the residual limit of coumaphos in foods (such as 0.05 mg/kg). Therefore, development of a coumaphos specific detection method which can meet the standard requirement and is suitable for on-site rapid screening has urgent practical requirements. At present, the detection method based on the fluorescent probe has great potential in the field of pesticide residue analysis and detection due to the advantages of high sensitivity, quick response, simplicity and convenience in operation and the like. Among them, carbon Dots (CDs) are regarded as an ideal fluorescent sensing platform by virtue of their excellent water solubility, adjustable luminescence properties, low toxicity and good biocompatibility as an emerging fluorescent nanomaterial. Among the synthesis methods of CDs, the hydrothermal method is widely used because of simple process, mild conditions and easy mass production. In recent years, the use of biomass waste as a carbon source for the production of CDs has become a cost-effective and environmentally friendly strategy. The patent document CN2021113377754 discloses a method for preparing fluorescent carbon quantum dots and detecting lemon yellow by using alternanthera philoxeroides, wherein the preparation process of the fluorescent carbon quantum dots comprises the following steps of weighing alternanthera philoxeroides powder and thiourea in a beaker according to a mass ratio of 1:1, adding water, stirring, transferring to a reaction kettle, placing into a baking oven for reaction at a set temperature, naturally cooling to room temperature after the reaction is finished, carrying out suction filtration to obtain a carbon quantum dot solution, dialyzing, rotary evaporating and drying to obtain the carbon quantum dot powder. The prepared fluorescent carbon quantum dot detection lemon yellow belongs to a turn off type, has the advantages of high sensitivity, strong stability, good selectivity, low cost and the like, and can be used as a convenient and accurate lemon yellow rapid detection method. However, the patent document only relates to the preparation of carbon quantum dots based on alternanthera philoxeroides and the application thereof in detecting lemon yellow, and does not relate to the fluorescent detection of synthesizing the carbon quantum dots and pesticide coumaphos by taking biomass lotus seeds as carbon sources. The direct application of biomass-based CDs to the specific detection of coumaphos in complex matrixes still faces some challenges, firstly, unmodified CDs often lack specific recognition capability for target analytes and are easy to be interfered by coexisting substances, secondly, the fluorescence properties (such as quantum yield and stability) of the CDs directly influence the sensitivity and reliability of the detection, and furthermore, how to simultaneously realize the high-performance preparation and specific functionalization of the CDs through a simple process is a key for improving the sensing application value of the CDs. The prior art shows that the optical properties of CDs and their interactions with targets are highly dependent on the chemical composition of their carbon source precursors and the surface modification during synthesis. Lotus seeds are used as a biomass raw material rich in protein and starch, and nitrogen, oxygen and other heteroatoms contained in the lotus seeds naturally are favorable for forming intrinsic doping in the carbonization process, so that the electronic structure and fluorescence characteristics of CDs are optimized. In addition, CDs are subjected to aftertreatment by adopting a proper surface modification passivating agent, so that surface defects can be further passivated, specific functional groups are introduced, and the fluorescence behavior and interaction with metal ions or organic molecules of the CDs are regulated, so that the possibility is provided for constructing a fluorescence sensing system. The biomass lotus seeds are used as carbon sources, and the carbon quantum dots which are synthesized by a one-step hydrothermal method and are modified by the passivating agent ethanolamine in a functional mode are called LS-MEA-CDs. In order to detect coumaphos pesticide residue, a fluorescence "off-on" detection method is designed, wherein the detection principle