DPV Determination of Dopamine with Nitrogen Doped Graphene and Hairpin DNA Compositly Modified Electrode as Working Electrode

Glassy carbon electrode (GCE) was polished to give a mirrorlike surface, and 5.0 μL of nitrogen doped graphene suspension were dropped onto the surface of GCE which was then dried at 50℃ radiated from an IR-lamp. Nitrogen doped graphene modified GCE was thus obtained. Furthermore, 10 μL of 5.0 μmol·L^-1 of H DNA solution were dropped onto the surface of nitrogen doped graphene modified GCE to obtain the nitrogen doped graphene and H DNA modified GCE. This compositly modified GCE was used as working electrode in DPV determination of dopamine (DA) in human blood serum. It was shown that better electrocatalytic action on electro-oxidation of DA at the compositly modified GCE was obtained. Linear relationship was found between values of oxidation peak current and concentration of DA in the range of 4.0×10^-7-6.0×10^-5mol·L^-1, and the detection limit (3s/k) was 6.6×10^-8mol·L^-1. In DPV determinations, pH 6.5 PBS was used as supporting electrolyte. In the analysis of human blood serum, the sample was pretreated as follows:2.0 mL of the serum sample were taken and 4.0 mL of methanol was added and the mixture was centrifuged for precipitation. 2.0 mL of the supernatant were taken, and an equal volume of pH 6.5 PBS was added and mixed thoroughly. The solution obtained was used for DPV determination. To prepare standard curve, a series of DA standard solutions with various concentrations were prepared by dilution with pH 6.5 PBS and analyzed by DPV, and data of various oxidation peak current given by the standard DA were recorded. The proposed method was used in analysis of 3 blood samples and test for recovery was made by standard addition method using these samples as matrixes, giving results of recovery in the range of 90.0%-110%, and RSDs (n=5) were found in the range of 1.7%-3.7%.