▎ 摘　　要

A new method for the determination of the phenol fraction of olive oil is reported. An optical nanosensor based on graphene quantum dots, obtained by pyrolysis of citric acid, was specifically developed for this purpose. The ensuing fluorescence sensing method, which is simple, and highly sensitive and reproducible, was used here to determine gallic acid and oleuropein as model analytes commonly found in olive oils, as well as the phenolic concentration of olive oil real samples. The detection limits were lower than 0.12 mg L-1 and the precision, expressed as relative standard deviation, lower than 1.7%. (C) 2014 Elsevier B.V. All rights reserved.