Voltammetric behavior and determination of rutin at a single-walled carbon nanotubes modified gold electrode

Abstract

The voltammetric behavior of rutin at a single-walled carbon nanotubes (SWNTs) modified gold electrode has been investigated. At the modified electrode rutin can generate a pair of peaks when the solution pH is smaller than 11. In a 0.1M phosphate buffer solution (pH 5.0), the peak potentials are about 0.35V, which changes with scan rate. The electrochemical reaction involves two electron transfer, accompanied by two protons. The electrochemical process is controlled by adsorption. The adsorption mode of rutin at the modified electrode basically belongs to Langmuir adsorption and the maximum adsorption amount is estimated to be about 1.4×10−9molcm−2. The diffusion coefficient of rutin in the solution is determined to be about 2.0×10−5cm2s−1. The experimental conditions such as solution pH, accumulation time and accumulation potential, are optimized. Under the selected conditions (i.e. solution pH 5.0 and accumulation time of 210s under open circuit), the peak current is linear to the rutin concentration over the range of 2.0×10−8M to 5.0×10−6M, and the detection limit is estimated to be 1.0×10−8M. The method has been applied to the determination of rutin in drug tablets and flos sophorae buds, and the recoveries are 98–105%. The electrode exhibits good stability and reproducibility. In addition, the influence of various foreign species has been studied. It is observed that in the presence of hemoglobin the peak current of rutin decreases linearly, which can be used for the indirect determination of hemoglobin.