Electroanalysis of nicotine at an electroreduced carboxylated graphene modified glassy carbon electrodeElectronic supplementary information (ESI) available. See DOI: 10.1039/c4ay01872a

A carboxylated graphene (CG) modified glassy carbon electrode (GCE) was prepared by cast-coating a CG solution on a GCE surface, for quantitative analysis of nicotine based on cyclic voltammetry after potentiostatic enrichment of nicotine at −1.1 V for 240 s in 0.1 M KH 2 PO 4 -Na 2 HPO 4 buffer solution (pH 7.0). At this enrichment potential, partially electroreduced CG (ERCG) was obtained, as characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and electrochemistry techniques. The oxidation peak current of nicotine at the ERCG/GCE after a semi-derivative treatment responded linearly to nicotine concentration from 2 to 5 μM and from 5 to 60 μM, with a limit of detection of 0.1 μM. The ERCG/GCE gave analytical performance superior to that at a bare GCE, and the semi-derivative treatment notably improved the signal resolution. The ERCG/GCE was used to determine nicotine in real tobacco samples, with recoveries over 95%. Nicotine is determined at a glassy carbon electrode modified with partially electroreduced carboxylated graphene by cyclic voltammetry and semi-derivative treatment after enrichment at −1.1 V in 0.1 M pH 7.0 phosphate buffer solution.