Strong Enhancement of the Chemiluminescence of Hydrogen Sulfite-Oxidant Systems in the Presence of N,S-Doped Graphene Qu
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Strong Enhancement of the Chemiluminescence of Hydrogen Sulfite-Oxidant Systems in the Presence of N,S-Doped Graphene Quantum Dots, and Its Application to the Determination of Folic Acid in Spinach and Kiwifruit Samples Junmei Zhang 1 & Suqin Han 1 Received: 20 September 2018 / Accepted: 13 December 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract The oxidation of bisulfite by classical oxidants such as hypochlorite, hydrogen peroxide, and permanganate is accompanied by weak chemiluminescence (CL). It is reported here that the CL is strongly enhanced in the presence of nitrogen/sulfur co-doped graphene quantum dots (N,S-GQD), nitrogen-doped graphene quantum dots (N-GQD), or graphene quantum dots (GQD). The weak CL of the NaHSO3-NaClO system and the NaHSO3-H2O2 system in the neutral medium and of the NaHSO3-KMnO4 system in acidic solution is more than 1000-fold enhanced in the presence of N,S-GQD, about sixfold in the presence of N-GQD, and twofold in the presence of GQD. Fluorescence spectra and CL spectra indicate that the N,S-GQD-sensitized enhancement originates from energy transfer and electron transfer annihilation effects on the CL system. It is also reported that folic acid (FA; vitamin B9) causes a notable diminution in the N,S-GQD-NaHSO3-NaClO system. Based on this finding, a sensitive CL method is developed for the determination of FA in food samples. The method works in the 0.5 to 70.0 μmol/L FA concentration range and the limit of detection is 78.0 nmol/L. Keywords Chemiluminescence . Nitrogen and sulfur co-doped graphene quantum dots . Oxidants . Sodium bisulfite . Folic acid
Introduction Graphene quantum dots (GQD), an edge-bound nanometersize graphene pieces, exhibit outstanding optical and electronic properties due to quantum confinement and edge effects (Lin et al. 2014). GQD has low toxicity, high biocompatibility, robust organic inertness, and stable photoluminescence, which make it a great promising material for applications in photo catalyst, energy conversion, sensor, bioimaging, and so on (Shen et al. 2012; Lin et al. 2014; Wang et al. 2015). However, the surface chemical structure and poor optical characteristics of GQD, especially relatively low fluorescence quantum yield (FLQY), limit its practical applications (Yang Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12161-018-01419-x) contains supplementary material, which is available to authorized users. * Suqin Han [email protected] 1
School of Chemistry and Material Science, Shanxi Normal University, Linfen 041000, Shanxi, People’s Republic of China
et al. 2015; Nemati et al. 2018). Heteroatom doping can endow graphene with various new or improved electromagnetic, physicochemical, optical, and structural properties (Wang et al. 2014). Doping is also proved to tailor the defect in the surface and tune intrinsic properties of GQD (Qu et al. 2013; Chen et al. 2017). In particular, the FLQY of the doped GQD is higher than that of the undoped ones. Among these
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