Use of Carbon Dots Synthesized from Citrate as a Fluorescent Probe for Quercetin Determination in Tea and Beer Samples

Nattany De Paula,André Lavorante,Ana Paula Paim,Raquel Milani

doi:10.21577/0103-5053.20190145

Abstract

In this work, carbon dots (CDs) prepared by a one-step hydrothermal method were employed for the determination of quercetin in teas and beers. The fluorescence quenching of CDs was proportional to the concentration of quercetin. Under optimum experimental conditions, linear quenching was observed for quercetin in the range of 1.0 to 10 mg L-1 (F/F0 = (0.1511 ± 0.0075)[Q] + (0.8922 ± 0.0384), R2 = 0.9926), at room temperature, using 80 μL CDs and 0.1 mol L-1 Na2HPO4/NaOH buffer solution (pH 11.0). A limit of detection (3σ criterion) of 0.85 mg L-1, and a relative standard deviation of 0.21% (n = 3) for 4.0 mg L-1 quercetin solution was obtained. Addition and recovery tests with tea and beer samples were performed resulting in recoveries at the range between 80 and 118%. This procedure served successfully to determine quercetin in beer and tea samples presenting high sample throughput.

Highlights

There is a growing concern about the quality of life, leading to a greater number of people who care about having a healthier diet
The results showed that the Na2HPO4/NaOH buffer solution promoted greater carbon dot stability and greater quenching effect for quercetin analysis
We demonstrated the applicability of a fluorescence procedure using carbon dots synthesized with citrate to determine the amount of quercetin in beer and tea samples

Summary

Introduction

There is a growing concern about the quality of life, leading to a greater number of people who care about having a healthier diet. There are several methods for determination of quercetin in foods and beverages, such as high performance liquid chromatography (HPLC) with ultraviolet-visible (UV-Vis) and fluorescence detection,[3,10] spectrophotometric method,[11] capillary zone electrophoresis,[12] solid phase extraction,[13] and near-infrared spectroscopy and chemometrics.[14]. These methods may be reasonably accurate and sensitive, they have certain disadvantages, such as laborious analysis, high conductor consumption, expensive instruments and time-consuming analysis. The vessel was cooled to room temperature and the solution containing 25 mg mL-1 of carbon dots was stored in a Falcon tube and kept under refrigeration

Procedures for the detection of quercetin

Results and Discussion

Conclusions