Automatic determination of polyphenols in wines using laccase and terbium oxide nanoparticles

The analytical usefulness of the combined use of laccase, terbium oxide nanoparticles (Tb4O7NPs) and 8-hydroxypyrene-3-sulphonate trisodium (HPTS) for the determination of polyphenol compounds in wine samples is described. The system is based on the temporal inhibition by polyphenols on the decrease of the HPTS fluorescence in the presence of laccase and on the activating effect of Tb4O7NPs, which increase the reaction rate of the system, shortening analysis times. The method has been developed in a microplate format using an automatic reader, reaching a sample throughput of 35 samples h(-1). The dynamic range of the calibration graph is 0.5-12 μM gallic acid, which was chosen as model analyte, and the detection limit is 0.14 μM. Precision data, expressed as relative standard deviation, ranged between 2.5% and 6.3%. The method was applied to the analysis of several wine samples, obtaining recovery values in the range of 80.0-108.3%.