▎ 摘　　要

NOVELTY - Preparing graphene quantum dot fluorescent probe comprises e.g. preparing graphene quantum dot fluorescent probe by cutting the green plant leaves, soaking in absolute ethanol, stirring and allowing to stand, centrifuging, rotating and evaporating the supernatant to obtain a mud-shaped solid, adding water into mud-shaped solid, heating, adding ethanol to dissolve to obtain the fluorescent probe with red emission spectrum band graphene quantum dots, preparing 2-paraquat solution by weighing the paraquat, adding the solution into a volumetric flask, and obtaining a paraquat solution, configuring a paraquat solution through a step-by-step dilution method, and sealing and storing for later use, detecting paraquat by using fluorescent probe of graphene quantum dots by removing absolute ethanol into seven quartz cuvette with optical path by using micro sample injector, and removing fluorescent probe of the graphene quantum dots from seven quartz cuvette by using micro sample injector. USE - The prepared graphene quantum dot fluorescent probe is useful for detecting paraquat. ADVANTAGE - The method has highly selective recognition and high-sensitivity detection of paraquat free radicals and the detection limit is 109 moll1, is simple and easy to implement, has high selectivity, high sensitivity, and low detection limit. DETAILED DESCRIPTION - Preparing graphene quantum dot fluorescent probe comprises mutually overlapping fluorescence emission spectrum of the graphene quantum dot fluorescent probe and the maximum absorption wavelength of the paraquat, according to the fluorescence resonance energy transfer principle, the energy donor in the fluorescent group of the graphene quantum dot fluorescent probe generates fluorescence emission, transferring energy to the nearby energy acceptor paraquat molecules without radiation through interaction between the dipole-dipole, so that the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, according to the preparation process of the graphene quantum dot fluorescent probe for paraquat detection, the preparation process of the graphene quantum dot fluorescent probe comprises (1) preparing graphene quantum dot fluorescent probe by cutting the green plant leaves into 1-2 cm, soaking in 40-60 ml absolute ethanol, stirring at 500 rotations/minutes for 20-40 minutes, stirring and allowing to stand for 10-20 minutes, centrifuging the obtained solution at 8000 revolutions/minutes for 10 minutes, taking 40 ml supernatant, rotating and evaporating the supernatant to obtain a mud-shaped solid, adding 5 ml water into mud-shaped solid, heating for 5-10 minutes in a microwave oven, and finally adding ethanol to dissolve to obtain the fluorescent probe with the red emission spectrum band graphene quantum dots, (2) preparing 2-paraquat solution by weighing the paraquat 2.572 g, adding the solution into a 100 ml volumetric flask, removing a concentration of 0.1 mol/l1 sodium hydroxide solution with a mass fraction of 1% to a constant volume scale of a volumetric flask, and obtaining a paraquat solution with the concentration of 0.1 mol/l1 in the concentration of 0.1 mol/l1, configuring a paraquat solution with the concentration of 102, 103, 104, 105, 106 and 107 mol/l 1 gradient through a step-by-step dilution method, and sealing and storing for later use, detecting paraquat by using fluorescent probe of graphene quantum dots by removing 940 microl absolute ethanol into the seven quartz cuvette with 5 ml of 10 mm optical path by using a micro sample injector, and removing 30 mul fluorescent probe of the graphene quantum dots from the seven quartz cuvette by using a micro sample injector, and finally dropwise adding 30 mul prepared paraquat solution with different concentration gradients from low to high, and dropwise adding a paraquat solution of 101, 102, 103, 104, 105, 106 and 107 mol/l1 into a cuvette containing 970 mul ethanol, the solution concentration of the graphene quantum dot fluorescent probe is diluted to 103, 104, 105, 106, 107, 108 and 109 mol/l to 1, after adding the target analyte paraquat, the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and trace detection on the paraquat is achieved.