| Since the advent of chemically modified electrodes,it has always been an important research direction in the field of analytical chemistry,and has been widely used in environmental protection,clinical medicine,food and other fields.Carbon-based nanomaterials and metal composite nanomaterials provide a basis for the further development of modified electrodes due to their better loading capacity,biocompatibility and electrocatalytic performance.This article mainly studies the preparation of modified electrodes of different nanocomposite materials and their application to the detection of hydroquinone,catechol,glucose and glycine.1.The small graphene oxide is obtained by constant voltage electrolysis of the large graphene oxide,and the small graphene oxide(GO)dispersion is drip-coated on the surface of the glassy carbon electrode,and the small graphene modification is prepared by electrochemical reduction electrode(ERGO/GCE).The electrochemical behavior of hydroquinone(HQ)and catechol(CC)on ERGO/GCE was studied by cyclic voltammetry and differential pulse voltammetry.The experimental results show that the modified electrode has good electrocatalytic activity for the electrochemical redox of HQ and CC,and can be applied to the detection of HQ and CC at the same time.The differential pulse voltammetry response of the two shows a good linear relationship with the concentration at2.9×10-6-2.0×10-4 mol/L and 2.0×10-4-2.0×10-3 mol/L.The detection limit of HQ and CC can reach 9.7×10-7 mol/L(S/N=3).The modified electrode has high sensitivity and strong stability.2.The graphene oxide/carbon nanotube composite is electropolymerized and deposited on the surface of the treated low-cost carbon fiber disk electrode,the modified electrode is subjected to cyclic voltammetric reduction treatment,and then copper-nickel nanoparticles are electrodeposited on the surface of the electrode to get Cu-Ni/ERGO/MWCNTs/CFE.Cyclic voltammetry and current time method were used to study the electrochemical performance of Cu-Ni/ERGO/MWCNTs modified electrode for glucose detection.The modified electrode has good electrocatalytic activity for glucose oxidation in 0.2 mol/L Na OH solution.The linear range is 1.9×10-6-4.4×10-4 mol/L and 4.4×10-4-3.6×10-3 mol/L,and the sensitivity is923.6?A·L/(mmol·cm2)and 302.6?A·L/(mmol·cm2),the detection limit is 6.7×10-7 mol/L(S/N=3).The relative standard deviation(RSD)is 0.5%(n=4).The modified electrode has the advantages of high sensitivity,good selectivity,good stability and high reproducibility.This sensor can successfully detect glucose in human serum with a recovery rate of 90.3%-92.5%.3.A two-step electrodeposition method is used to prepare CuNiHCF film on the electrode surface,and cyclic voltammetric scanning is performed in NaOH solution to transform the Cu/Ni HCF film into a cubic nano-Cu/Ni(OH)2 composite modified layer with uniform particles.And applied to the surface modification of glassy carbon electrode.The modified electrodes were characterized by scanning electron microscopy and AC impedance technology.The electrode has a better catalytic effect on glycine in alkaline medium.The experiment uses current-time curve to detect glycine,the linear range is 4.9×10-6-1.0×10-3mol/L and 1.0×10-3-7.0×10-3 mol/L,the detection limit is 1.9×10-6 mol/L(S/N=3),the sensitivity is 754.8?A·L/(mmol·cm2)and 336.3?A·L/(mmol·cm2),and the RSD is 1.0%(n=6).Applied to the analysis of glycine in calcium carbonate glycine capsules,the recovery rate is 96%-103%,and the actual sample detection performance is good. |
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