Poly(glutamine) film-coated carbon nanotube paste electrode for the determination of curcumin with vanillin: an electroanalytical approach

Poly(glutamine) film-modified carbon nanotube paste electrode (PGAMCNTPE) was prepared through the electropolymerization technique. The prepared electrode was characterized by Field Emission Scanning Electron Microscope (FE-SEM) and electrochemical approaches. It was applied to electrochemical monitoring of curcumin in phosphate buffer of pH 7.5 using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The bare carbon nanotube paste electrode was unable to identify curcumin, but PGAMCNTPE detects curcumin oxidation at 0.168 V and reduction at 0.098 V with good current sensitivity. Under calibrated conditions, the PGAMCNTPE shows the linear voltammetric response from 0.4 to 6 and 6 to 10 mu M for curcumin, with the lower detection limit of 2.79 x 10(-8) M. The planned curcumin sensing strategy was applied to food supplement with excellent recovery from 90 to 97%. Also, a simultaneous determination was performed with vanillin with less interference effect.