Determination of Total Phenolic Compounds in Common Beverages Using CdTe Quantum Dots

Abstract

In this study, we describe a method of total phenolic compounds determination based on CdTe quantum dot (QD) fluorescence recovery in the presence of analyte. Polyphenols present in the solution were reducing agents, acting as electron donors to the CdTe–sodium periodate system, thus leading to perturbation of the transfer of excited electrons from QD to the acceptor molecules occurring in the absence of polyphenols. Using the developed technique the polyphenol content in green tea, black tea, Pu-Erh tea, lemon balm, peppermint, lime, chamomile, and coffee infusions was successfully determined. The limit of detection of the method amounted to 0.63 nM of (+)-catechin equivalent, which makes this technique nearly one order of magnitude more sensitive than the commonly used Folin–Ciocalteu method. Additionally, lack of impact of interference from proteins and reducing sugars on the results makes this technique an advantageous alternative to the Folin–Ciocalteu assay. Practical Applications The developed method for total phenolic compound determination, thanks to higher specificity and a low detection limit may be a beneficial alternative to the popular Folin–Ciocalteu assay. The applications of the described technique include plant raw material and product nutritional quality assessment as well as studying the effects of a polyphenol-rich diet on human health. The assay is easy to use both in industry laboratories as well as in research and development.