Fabrication of Graphene Modified Screen Printed Carbon Electrode and Its Application for Voltammetric Determination of Antioxidant Capacity using PFRAP

PFRAP (potassium ferricyanide reducing power) is an antioxidant capacity assay using the spectrophotometric technique. This assay utilizes color changes as a basis of detection, then the measurement can be disturbed by sample color and turbidity. This study aims to develop a voltammetry technique for antioxidant capacity measurement using potassium ferricyanide, K3Fe(CN)(6), as the reagent. Measurements were conducted with the cyclic voltammetry technique at graphene modified screen-printed carbon electrode (SPCE-G). The antioxidant capacity was express as mg quercetin equivalent/g sample (mg QE/g). The results showed that the voltammetry technique for antioxidant capacity measurement at SPCE-G provides linearity with R-2 of 0.9790 and sensitivity of 1.6846 mu A mu M-1, the result was better than the measurement using SPCE. The application of the developed method for antioxidant capacity measurement of Syzygium polyanthum leaf extract showed the antioxidant capacity of 490.117 mg QE/g extract, higher than the result of spectrophotometric method (293.5758 mg QE/g extract). Otherwise, its analytical performances need to be improved, the voltammetric method at SPCE-G was potential to be applied for the antioxidant capacity determination of natural extract.