Preparation And Application Of Palladium Doped Poly(Amino Acid) Modified Electrode

Palladium doped poly (amino acid) modified electrode(Pd-PAA/GCE) wasprepared on the carbon glassy electrode, the electrochemical behavior of epinephrine(EP),dopamine(DA),5-hydroxytryptophan (5-HTP) and dopamine (DA), xanthine (Xa) and5-hydroxytryptophan (5-HTP) at the prepared Pd-PAA/GCE were studied by cyclicvoltammetry and differential pulse voltammetry. Palladium doped poly (L-arginine)modified glassy carbon electrode(Pd-PLA/GCE) was used to determination of EP,simultaneous determination of5-HTP and DA, Xa and5-HTP, and the electrochemicalbehavior of DA at different amino acid modified electrodes were studied by cyclicvoltammetry. The modified electrodes were used to determination of samples withsatisfactory results.In the entire study, the principle problem must be solved were:(1) to study the preparations and characterizations of the palladium doped poly(L-arginine) modified electrode;(2) to study the preparations and characterizations of thepalladium doped poly (L-methionine) modified electrode;(3) to study the preparations andcharacterizations of the palladium doped poly (L-phenylalanine) modified electrode;(4) tostudy the preparations and characterizations of the palladium doped poly (L-valine)modified electrode;(5) to discuss the electrochemical behavior of EP;(6) to discuss theelectrochemical behavior of DA;(7) to discuss the simultaneous determination of5-HTPand DA;(8) to discuss the simultaneous determination of Xa and5-HTP.The principle works are researched as follows:1. A palladium doped poly (L-arginine) modified electrode was prepared by cyclicvoltammetric method. The polymerization conditions and the electrochemical behavior ofEP were studied. In pH3.0phosphate buffer solution, a pair of oxidation and reductionpeaks were observed at peak potential Epa=0.500V and Epc=0.406V at a scan rate of160mV/s. By cyclic voltammetry and differential pulse voltammetry, the peak current of EPwas proportional to the concentration in a range of5.00×10-7~1.00×10-5mol/L and that of1.00×10-5~1.00×10-4mol/L. The detection limit was1.0×10-7mol/L and8.0×10-8mol/L.The method was successfully applied to the determination of EP in injection with satisfactory results.2. A palladium doped poly (L-arginine) modified electrode was prepared by cyclicvoltammetric method. The electrochemical behaviors of5-HTP and DA and cyclicvoltammetric method for the simultaneous determination of5-HTP and DA were studiedon the palladium doped poly (L-arginine) modified electrode. In pH2.0phosphate buffersolution, the modified electrode gave a pair of redox peaks at Epa=0.515V, Epc=0.464V forDA and one oxidation peak at Epa=0.643V for5-HTP with the scan rate of160mV/s. Twoseparated oxidation peaks of5-HTP and DA was128mV. Under the optimum conditions,the linear ranges for simultaneously determination of5-HTP and DA were9.00×10-7~1.00×10-5mol/L,1.00×10-5~4.00×10-5mol/L for5-HTP and7.00×10-7~1.00×10-5mol/L,1.00×10-5~4.00×10-5mol/L for DA. The detection limits of5-HTP and DA were7.0×10-7mol/L and5.0×10-7mol/L. The method was successfully of applied to the determination of5-HTP and DA in medicaments with satisfactory results.3. A palladium doped poly (L-methionine, L-phenylalanine or L-valine) modifiedelectrode were prepared by cyclic voltammetry. The electrochemical behavior of DA atthree kinds of modified electrodes were studied by the electrochemica method. The resultshowed that both oxidation and reduction peak potentials almost no change and the peakcurrent changed slightly in different modified electrodes, but not too much. That to say, thetype of amino acids will change the sensitivity, but it will not change the electrochemicalprocess of DA. Under the optimal conditions, the modified electrode can be applied to thedetermination of DA, and the peak current of DA was proportional to the concentration bycyclic voltammetry (CV) and differential pulse voltammetry (DPV). The detection limitwas5.0×10-7mol/L (CV) and2.0×10-7mol/L (DPV). The method was successfully appliedto the determination of DA in medicaments with satisfactory results.4. A palladium doped poly (L-arginine) modified electrode(Pd-PLA/GCE) wasprepared by the cyclic voltammetric method. The Pd-PLA/GCE was characterised usingelectrochemical impedance spectroscopy. The electrochemical behaviors of xanthine (Xa)and5-Hydroxytryptophan (5-HTP) at the Pd-PLA/GCE were investigated by cyclicvoltammetry (CV) and differential pulse voltammetry (DPV). The experimental resultssuggested that Pd-PLA/GCE displayed excellent electrochemical catalytic activitiestowards Xa and5-HTP, and it can be used to determine Xa and5-HTP simultaneously. The peak potential of Xa and5-HTP were1102mV,643mV by CV, and1055mV,580mV byDPV. The linear ranges for Xa and5-HTP were5.00×10-6~7.50×10-4mol/L and7.50×10-7~1.00×10-4mol/L, with detection limits of2.5×10-6mol/L,5.0×10-7mol/L by CV,and2.0×10-6mol/L,4.0×10-7mol/L by DPV, respectively. The Pd-PLA/GCE showed agood repeatability and stability. The proposed method was applied in the determination ofXa and5-HTP in samples with satisfactory results.