Electrochemical sensor based on Nbim/CNT composite for selective determination of luteolin in the flavonoids

Abstract

A new Nbim/CNT-modified glassy carbon electrode, combining the selective adsorptive capability of nitro-substituted 3,3′-bis(indolyl)methane (Nbim) to flavonoids with the unique properties of CNTs with enlarged active surface area and extraordinary electrical conductivity, was fabricated for the analysis of luteolin with high sensitivity and selectivity. Compared to bare GCE, the Nbim/CNT-based modified electrode could synergistically enhance accumulation of luteolin from the flavonoid sample solution to the electrode surface and result in an 18-fold increase of the oxidation current of luteolin in phosphate buffer solution at pH6.0. Using differential pulse voltammetry method, the oxidation current increased linearly with luteolin concentration at the range of 5–320nM, with a detection limit of 0.6nM. The proposed electrode could also effectively avoid the interference of similar structural flavonoids (quercetin, myricetin, and apigenin), which made the proposed sensor suitable for the accurate determination of luteolin in the actual samples.