Employment of electrochemically synthesized TGA–CdSe quantum dots for Cr3 determination in vitamin supplements

Abstract

The fluorescence quenching of TGA-CdSe quantum dots (QDs) was used for Cr(3+) quantification in vitamin supplements. The QD was electrochemically synthesized, demonstrating high reproducibility with control of particle size, thus making it a clean method, without the presence of reducing agents. Under ideal conditions, with the fluorescence band at 551 nm (excitation 365 nm), the maximum fluorescence quenching was observed at pH 4.0, with a time of 200 s for each data acquisition. Under optimum experimental conditions, linear quenching was observed for Cr(3+) in the range of 25.0-325.0 ng L(-1) (R=0.9996, n=6), a limit of detection of 5.67 ng L(-1), and relative standard deviation of 4.43% (n=10). The recovery test for Cr(3+) quantification in vitamin supplements presented results from 82% to 98%. These Cr(3+) determination results were compared to the same vitamin supplement sample using flame atomic absortion spectrometry (FAAS) method, and no significant differences were observed at 95% confidence level.

Fluorescent nanoprobes for sensing and imaging of metal ions: Recent advances and future perspectives

“…For instance, Chen et al [189] utilized thioglycerol-capped CdS QDs as an ion-selective probe to determine copper, zinc, and ferric ions in buffer solutions. Due to the effect on photoluminescence (PL) behaviors of QDs by metals ions, QDs have also been utilized as fluorescent probes for many metal ions, including K + [188], Ag + [190], Cd 2+ [191,192], Cu 2+ [193-200], Fe 2+ , Hg 2+ [187,201-207], Pb 2+ [208], Cr 3+ [209,210], Fe 3+ [211], Sb 3+ [212], Co 2+ [213], Ba 2+ [214], Ca 2+ and Ni 2+ [215]. Based on this principle of direct interaction of metal ions with QDs, the Zhu group [195] reported L-cysteine-capped NIR-emitting CdSeTe QDs for selective detection of Cu 2+ , with a LOD of 7.1 nM.…”

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

“…The linear equation was estimated as F 0 /F = (0.1511 ± 0.0075)[Q] + (0.8922 ± 0.0384) (R 2 = 0.9926, n = 3), (the F 0 and F are the fluorescence intensities in the absence and presence of quercetin, respectively, and [Q] is the concentration of quercetin in mg L -1 ), with a limit of detection of 0.85 mg L -1 and relative standard deviation (RSD) 0.21% (n = 3, 4 mg L -1 ). This phenomenon can be described by the Stern-Volmer equation, 45 as shown in equation 1. The Stern-Volmer equation predicts a linear dependence of F 0 /F on quencher concentration [Q].…”

“…Where F 0 and F are the fluorescence intensity of the carbon dot solution in the absence and presence, respectively, of quercetin and K sv, this is referred to as the quenching constant or the Stern-Volmer constant, established at 0.1511 L mg -1 . 45,46 F 0 /F = 1 + K sv [Q] (1)…”