Preparation Of Amino Acid And Metal Layered Modified Electrode And Application

In this paper, Silver and L-cysteine layered modified electrode and nickel and L-cysteine layered modified electrode were fabricated by cyclic voltammetry. The electrochemical behaviors including the adsorption and diffusion characteristics of dopamine, ascorbic acid, sunset yellow, tartrazine were studied on silver and L-cysteine layered modified electrode,and the electrochemical behaviors of baicalin was studied on the nickel and L-cysteine layered modified electrode. New methods for individually and simultaneously determining were developed. Also different metals(Ag, Au, Cu, Ni)and different amino acids(L-cysteine, L-phenylalanie, L-histidine) were combined each other to make layered modified electrodes. Finally, silver and L-phenylalanie layered modified as the best layere delectrode to research the electrochemical behaviors of thymol. In the best conditions, the catalytic ability of modified electrode was enhanced, which further improved the determination sensitivity and declined the detection limit analysis of drug and coloring with layered electrode, such as dopamine of bananas, ascorbic acid of the urine, sunset yellow and tartrazine of drinks, baicalin of tablets and thymol of pediatric compound thymol powder all obtain satisfactory results.The major problems to be solve in working process are as fellows: 1)Fabrication of PLC/Ag/GCE and investigation of catalytic ability and electrochemical impedance; 2)To study the preparations and properties of PLC/Ni/GCE; 3)Preparation and comparison of all kinds of metal amino acids layered modified electrode; 4)Study of electrochemical behavior of dopamine at PLC/Ag/GCE; 5)Study of electrochemical behavior of simultaneous determination of dopamine and ascorbic acid at PLC/Ag/GCE; 6)To discuss the separate and simultaneous determination of sunset yellow and tartrazine at PLC/Ag/GCE; 7)Study of electrochemical behavior of baicalin at PLC/Ni/GCE; 8)Study of electrochemical behavior of thymol at PLF/Ag/GCEThe main works and the detail achievements were exhibited as follows:1. Silver and L-cysteine layered modified electrode was fabricated by cyclic voltammetry,The electrochemical behavior of dopamine was studied were studied by cyclic voltammetry and differential pulse voltammetry on the modified electrode. A new method was developed for determination of trace dopamine. The experimental results indicated that in phosphate buffer solution at p H = 3.0 with the scan rate of 100 m V/s, a pair of redox peaks were observed at peak potential Epa=0.452 V and Epc=0.404 V. The peak current and concentration of dopamine in 7.50×10-7~1.00×10-5mol/L and1.00×10-5~1.00×10-4mol/L had good linear relationship by cyclic voltammetry, the detection limit was 5.0×10-7mol/L. The peak current and concentration of dopamine in2.50×10-7~7.50×10-6mol/L and 7.50×10-6~1.00×10-4mol/L had good linear relationship by differential pulse voltammetry, the detection limit was 7.5×10-8mol/L. The method has been applied to the determination of dopamine in the banana with satisfactory results2. Silver and L-cysteine layered modified electrode was fabricated by cyclic voltammetric method. A new method was developed for simultaneous determination of dopamine and ascorbic acid by cyclic voltammetric method. The experimental results indicated that in phosphate buffer solution at p H = 3.0 with the scan rate of 120 m V/s,The oxide peaks of dopamine and ascorbic acid were separated at 0.209 V. The linear range for the determination of dopamine and ascorbic acid were 1.00×10-6~2.50×10-4mol/L and7.50×10-6~1.00×10-3mol/L,The detection limits were 5.0×10-7mol/L and 2.5×10-6mol/L.3. Silver and L-cysteine layered modified electrode was fabricated by cyclic voltammetric method. The electrochemical behavior of sunset yellow and tartrazine was studied by differential pulse voltammetry on the modified electrode. A new method was developed for simultaneous determination of sunset yellow and tartrazine. The experimental results indicated that a pair of redox peaks of sunset yellow and oxide peak of tartrazine were observed at peak potential of 0.760 V, 0.701 V and 1.013 V. The oxide peaks of sunset yellow and tartrazine were separated at 0.253 V in phosphate buffer solution at p H = 4.0.The linear range for the determination of sunset yellow and tartrazine were5.00×10-7~3.00×10-4mol/L and 7.50×10-6~7.50×10-4mol/L The detection limit were7.5×10-8mol/L and 2.5×10-7mol/L. The method has been applied to the determination of sunset yellow and tartrazine in beverage with satisfactory results.4. Nickel and L-cysteine layered modified electrode was fabricated by cyclic voltammetry.The electrochemical behavior of baicalin was studied were studied by differential pulse voltammetry. A new method was developed for determination of baicalin The experimental results indicated that under the optimized conditions, the striping peak current of baicalin was proportional to its concentration over the range of 5.00×10-7~1.00×10-5mol/L and1.00×10-5~1.00×10-4mol/L. The detection limit was 1.0×10-7mol/L. The method has been applied to the determination of baicalin in the drug with satisfactory results.5. Different kinds of layered modified electrode was fabricated by cyclic voltammetry.The electrochemical behavior of thymol was studied on these modified electrode.The result showed that determination of thymol use silver and L-phenylalanie has a maximum sensitivity. A new method was developed for determination of thymol. The experimental results indicated that an oxidation peak was observed at peak potential Epa=0.792 V. The linear ranges for the determination of thymol were 1.00×10-5~1.00×10-3mol/L(CV) and7.50×10-6~7.50×10-4mol/L(DPV). The detection limit were 5.0×10-6mol/L(CV) and8.0×10-7mol/L(DPV). The method has been applied to the determination of thymol in the drug with satisfactory results.