Determination of Cr(vi) in Leersia hexandra Swartz based on the efficient fluorescence energy transfer between CdTe@SiO2 nanoparticles and Rhodamine B

Abstract

A novel fluorescence probe for detecting Cr(VI) in Leersia hexandra Swartz (L. hexandra) was developed by fluorescence resonance energy transfer (FRET) from CdTe@SiO₂ to Rhodamine B. The energy migration occurred efficiently in the hydrogen phosphate–citric acid buffer solution in pH 8.4, in which the Rhodamine B (RhB) (acceptor) fluorescence intensity increased greatly. When Cr(VI) was added, fluorescence quenching occurred because of the electrostatic attraction between the Cr(VI) and RhB. There was a linear relationship between the concentrations of the Cr(VI) and the fluorescence-quenching intensities. Then a new determination strategy of Cr(VI) was built by using the CdTe@SiO₂–RhB system. Under the optimum conditions, Cr(VI) could be determined in the concentration range of 20–300 nM with a correlation coefficient of r = 0.9992 and a detection limit of 6.2 nM (n = 11). The proposed approach was successfully tested with Cr(VI)-containing real samples, L. hexandra, which has been found to be a Cr(VI) hyperaccumulator with an extraordinary accumulation capacity. The recovery rate obtained was 96.20–104.07%, demonstrating potential application in L. hexandra with satisfactory results.