Selective Determination Of Small Molecules By New Nanocomposite Modified Electrode

In recent years,nanocomposites have been widely used in various fields due to their special chemical properties.With the synergistic effect of nano composite materials,it also has excellent performance in the field of electrochemical analysis,which can be modified on the electrode surface,and developed a special electrochemical sensor with excellent properties.This paper reseaches selective determination of small molecules by new nanocomposite modified electrode.1.Simultaneous Determination of Diethylstilbestrol and Dienestrol at Polyglycine/graphene modified graphite electrodeThe polyglycine/graphene modified graphite electrode has been fabricated.It was used to study the electrochemical behavior of diethylstilbestrol and dienestrol.And It achieved the success of separation and determination.Compared with the bare graphite electrode,the redox peak current of DES and DIES has increased significantly and peak shape was sharp and the separation effect was also good.The results showed that the modified electrode has a good catalytic oxidation effect on DES and DIES.Under the optimized condition,in the presence of 5.00×10^-6 mol/L DES,the linear range of DIES was in a good linear relationships in range of 8.00×10^-7 to 6.00×10^-6 mol/L and 6.00×10^-6 to 2.50×10^-5 mol/L.The detection limit was8.50×10^-8 mol/L（3 times the noise）.In the presence of 1.00×10^-5 mol/L DIES,the linear range of DES was in a good linear relationships in range of 1.00×10^-7 to 7.00×10^-7 mol/L and7.00×10^-7 to 1.20×10^-5 mol/L.The detection limit was 1.00×10^-8 mol/L（3 times the noise）.2.Highly sensitive and selective detection of dopamine in the presence of ascorbic acid at graphene-multiwall carbon nanotube modified electrodeThis paper was prepared graphene oxide and multiwall carbon nanotube composite materials.And the modified electrode（REGO-MWCNTs/GCE）was prepared by the method of coating-method and electrochemical reduction.Developed a kind of highly selective electrochemical method for the simultaneous determination of ascorbic acid（AA）,dopamine（DA）,and uric acid（UA）.The modified electrode showed excellent electrocatalytic activity towards the oxidation of AA、DA and UA.Under the optimum experimental conditions,DA showed excellent linear response,ranging from 5.00×10^-61.10×10^-4 mol/L.The detection limit is 7.18×10^-7 mol/L（3 times noise method）.Determination of dopamine in human urine,the results were good.3.Determination of uric acid based on methylene blue immobilized on graphene-multiwall carbon nanotube modified electrodeIn this experiment,the composites of MB and ERGO-MWCNT were prepared by dropcoating method,and then were used as modified materials for electrochemical determination of uric acid.Cyclic voltammetry method was employed to study its electrocatalytic activity.It showed PMB/ERGO-MWCNTs modified electrode displayed good electrocatalytic activity toward UA,peak current increased significantly.The oxidation peak current was linear with the concentration of UA in the range from 5.00×10^-61.50×10^-4 mol/L and 1.50×10^-45.00×10^-4 mol/L.And the detection limit is 2.30×10^-7 mol/L（S/N=3）.Determination of UA in human urine,the results were good.