Sensitive voltammetric determination of rutin at a carbon nanotubes-ionic liquid composite electrode

A new composite electrode of multiwall carbon nanotubes (MWNTs) and 1-dodecyl-3-methylimidazolium hexafluorophosphate (DDMIMPF6) was fabricated to determine rutin. This electrode showed very attractive electrochemical performances compared to other kinds of ionic liquid modified electrodes and notably improved sensitivity and stability. Electrochemical behavior of rutin at the composite electrode had been investigated in pH 2.09 Britton-Robinson buffer solution by cyclic voltammetry and square wave voltammetry. The experimental results suggested that the composite electrode exhibited an electrocatalytic activity toward the redox of rutin. The electrochemical parameters of rutin were calculated with the results of the charge transfer coefficient (alpha) and the standard rate constant (k (s)) as 0.48 and 2.09 s(-1). Under the selected conditions, the reduction peak current was linearly dependent on the concentration of rutin in the range of 0.03-1.5 mu M, with a detection limit of 0.01 mu M (S/N = 3). The relative standard deviation for six times successive determination of 1 mu M rutin was 1.6 %. The method was successfully applied to the determination of rutin in tablets and urine samples without the influence of the coexisting substances. In addition, the MWNTs/DDMIMPF6 composite electrode exhibits a distinct advantage of simple preparation, surface renewal, good reproducibility, and stability.