Fluorescent carbon nanodots for sensitive and selective detection of tannic acid in wines

•Highly fluorescent C-dots were prepared by thermal carbonization.•C-dots fluorescence was selectively quenched by tannic acid.•C-dots acted as sensitive and selective nanoprobes for tannic acid determination.•No interference from common species present in wines was observed.•Tannic acid analysis in wines was performed with no need of sample pre-treatment.

Herein we describe an easy one step synthesis of carbon nanodots (C-dots) by thermal carbonization of 6-bromohexylboronic acid using two different amine compounds, polyethyleneglycol bis(3-aminopropyl (PEGA) and 1,2-aminopropane (DPA), at 180 °C in atmospheric oxygen. The as-synthesized C-dots were characterized by FTIR, HRTEM, NMR and fluorescence. The C-dots prepared using PEGA showed a strong emission at 440 nm with excitation at 362 nm. These C-dots exhibited analytical potential as sensing probes for tannic acid (TA) determination. pH effect, interferences, and analytical performance of the method were investigated. The method was found effective in the linear concentration range from 0.1 to 10 mg L−1 TA achieving a limit of detection equal 0.018 mg L−1 TA. The applicability of the method was demonstrated by direct measurements of TA in red and white wine samples. Validation of the method was achieved by spiking the wine samples with different standard TA concentrations obtaining recoveries in the range (90–112.5%). A probable mechanism by which TA quenched the C-dots fluorescence was proposed.

Graphical abstractTannic acid selectively quenched the fluorescence of carbon nanodots. Figure optionsDownload full-size imageDownload as PowerPoint slide