Investigation And Application Of Electrochemical Behavior Of Edible Pigment Using Modified Electrode

A poly(L-arginine)-electrochemically reduced graphene oxide modified glassy carbon electrode(PLA-ERGO/GCE)were prepared.The electrochemical behaviors of sunset yellow(SY),allura red(AR),tartrazine(TT),carmine(CA)and amaranth(AT)were studied by cyclic voltammetry and differential pulse voltammetry.New methods for individually and simultaneously determining edible pigment were developed.Scanning electron microscopy(SEM)and electrochemical impedance spectroscopy methods(EIS)were used to characterize the surface morphology of the modified electrode.The new established chemical modified electrode with function design on the surface was also used for determination of edible pigment in food with satisfactory results.The major problems to be solved in working process are as fellows:(1)to study the preparations and characterizations of the PLA-ERGO/GCE modified electrode;(2)to discuss the electrochemical behavior of SY,AR,TT,CA and AT;(3)to discuss the optimum determination conditions of SY,AR and TT;(4)to discuss the simultaneous determination of CA and AT.The principle works are researched as follows: 1.The poly(L-arginine)-electrochemically reduced graphene oxide modified glassy carbon electrode was prepared by cyclic voltammetric method.The polymerization conditions and the electrochemical behavior of SY were studied.In p H 3.5 phosphate buffer solution,a sensitive oxidation peak was observed at peak 0.826 V at a scan rate of 100 m V/s.With differential pulse voltammetry,the peak current of SY was proportional to the concentration in a range of 7.50×10-7~1.00×10-3 mol/L.The detection limit was 1.0×10-7 mol/L.This method was successfully applied to the determination of SY in injection with satisfactory results.2.The poly(L-arginine)-electrochemically reduced graphene oxide modified glassy carbon electrode was prepared by cyclic voltammetric method.The electrochemical behavior of AR based on this modified electrode was studied.In pH3.5 phosphate buffer solution,a pair of oxidation and reduction peaks were observed at peak potential 0.276 V and 0.086 V at a scan rate of 100 m V/s.With cyclic voltammetric,the determination linear range for AR was 7.50×10-7~1.00×10-4 mol/L.And the detection limit was 1.0×10-8 mol/L.This method was successfully applied to the determination of AR in real samples with satisfactory results.3.The poly(L-arginine)-electrochemically reduced graphene oxide modified glassy carbon electrode was prepared by cyclic voltammetric method.The electrochemical behavior of TT was studied.In p H 2.0 phosphate buffer solution,a sensitive oxidation peak was observed at peak 1.012 V at a scan rate of 100 m V/s.With differential pulse voltammetry,the determination linear range for TT was 1.00×10-6~2.50×10-4 mol/L.The detection limit was 2.5×10-7 mol/L.This method was successfully applied to the determination of TT in real samples with satisfactory results.4.The PLA-ERGO/GCE modified electrode was applied to study electrochemical behaviors of CA and AT.A new method of simultaneous determination of CA and AT was established in the basis of optimum conditions.In p H 2.5 phosphate buffer solution at a scan rate of 120 m V/s,two sensitive oxidation peaks at 0.736 V for CA and 0.884 V for AT were appeared respectively.Besides,a reduction peak at 0.658 V for CA was observed.The oxidation peaks of CA and AT were well defined and the separation of the two peaks was 121 m V.The determination linear range for CA and AT were 7.50×10-7~7.50×10-5 mol/L.And the detection limits for CA and AT were 7.5×10-8 mol/L and 2.5×10-7 mol/L,respectively.This method was successfully applied to the determination of CA and AT in reaal samples with satisfactory results.