Preparation of Carbon Quantum Dots From Tobacco Leaves And Itsapplication For Fluorescence Detection of Borax In Flour and its Products

In this study, carbon quantum dots (CQDs) were prepared using discarded tobacco leaves as the precursor material combined. And the method used in our experiment is a green, low-cost, and simple one-step hydrothermal method. The structural morphology, optical properties, and fundamental elemental composition of these CQDs were characterized via transmission electron microscope(TEM), X-ray photoelectron energy spectrum(XPS), X-ray diffraction map(XRD), UV-visible spectra(UV-Vis), and fourier infrared transform spectra(FT-IR). A fluorescence probe was developed with these CQDs for borax determination. Influencing factors including solution salt concentration, interfering substances, solution pH on the detection of borax were investigated. The fluorescence enhancement degree of these CQDs had a linear relationship with different concentrations of borax (0.025-10 mmol·L-1), r2 = 0.9961, and based on the formula 3σ/S, σ represents standard deviation of the detection data for 11 blank samples, S refers to the slope of the standard curve, LOD=8.0 μmol·L-1. Furthermore, we also initially elucidated the fluorescence enhancement mechanism of CQDs. Satisfactory results were obtained for borax determination in flour, bread and instant noodle samples