| As a very common nitrogen-containing compound,nitrite have been recognized by people.It is often added to various food processing processes,and human health is also closely related to it.With the increasing demand for food,various food additives are also absorbed by the body.When nitrite excessively enters the human body,it will cause the human body lack of oxygen and eventually die.Therefore,it is necessary to establish a fast and effective method for the detection of nitrite.In this paper,a mixture of amino acid and graphene was used as a modifier,and different types of amino acid-doped graphene modified electrodes were prepared by electrochemical methods.The electrochemical properties of different modified electrodes were compared.And realized the simultaneous determination of nitrite and ascorbic acid.A comprehensive and comprehensive study of nitrite was carried out..During the entire experimental research process,the main problems to be solved were:?1?Preparation and characterization of graphene modified electrodes with different amino acids;?2?The electrochemical behavior of nitrite in poly-L-lysine/graphene modified electrode;?3?Comparison of nitrite in three different amino acid/graphene modified electrodes:poly-L-arginine amino acid/graphene modified electrode,poly-L-tyrosine/graphene modified electrode and poly-L-histidine/graphene modified electrode,and the conclusion that poly-L-histidine/graphene modified electrode has the best effect on the determination of nitrite;?4?Nitrite and ascorbic acid Simultaneous determination on poly-L-tryptophan/graphene modified electrode.Main research content:1.Poly-L-lysine/graphene modified electrode,poly-L-arginine/graphene modified electrode,poly-L-tyrosine/graphene modified electrode,Poly L-histidine/graphene modified electrode and poly-L-tryptophan graphene modified electrode were successfully prepared by cyclic voltammetry?CV?.Scanning electron microscope?SEM?and alternating current impedance spectroscopy?EIS?were used to characterize the different electrodes.2.The electrochemical behavior of nitrite on the poly-L-lysine/graphene modified electrode was investigated.In the potential range of 0.31.2 V,the potential increment was 0.005 V,the pulse amplitude was 0.09 V,and the pulse width It is 0.02 s,pulse interval is 0.2 s,and differential pulse voltammetry scan is performed on nitrite under the condition of waiting time of 10 s.It has a good linear relationship with the peak current,and the detection limit is 5.0×10-77 mol/L.The method was used to detect the content of nitrite in daily food,and the results were satisfactory.3.Cyclic voltammetry and differential pulse voltammetry were used to compare the electrochemical behavior of nitrite on three different modified electrodes.The experimental results showed that nitrite had higher sensitivity and lower detection limit on poly-L-histidine/graphene modified electrode.The detection limit of nitrite using cyclic voltammetry on this electrode was 9.0×10-77 mol/L,the peak current of nitrite and its concentration was related over the range of 7.50×10-6 to 1.00×10-3 mol/L.The detection limit of nitrite on this electrode using differential pulse voltammetry was1.0×10-77 mol/L,and it had a linear relationship between the peak current and the concentration which ranged of 5.00×10-61.00×10-3 mol/L.These three electrodes were used to detect nitrite in food with satisfactory results.4.The electrochemical properties of nitrite and ascorbic acid?AA?on poly-L-tryptophan/graphene modified electrodes were studied by cyclic voltammetry?CV?,and simultaneous determination of nitrite and ascorbic acid?AA?was achieved.In the potential range of-0.11.3 V,the potential increment is 0.009V,the pulse amplitude is0.09 V,the pulse width is 0.07 s,the pulse interval is 0.1s,and the waiting time is 10 s,using the differential pulse voltammetry?DPV?scan for nitrite and ascorbic acid.The concentrations of nitrite and ascorbic acid were respectively in the range of 5.00×10-5 to1.00×10-3 mol/L and 2.50×10-4 to 7.50×10-3 mol/L,which showed a good linear relationship with its oxidation peak,and the detection limits were 6.0×10-77 mol/L for nitrite and 1.00×10-66 mol/L for ascorbic acid.The method was applied to the determination of nitrite and ascorbic acid in actual samples with satisfactory results. |
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