A sensitive nano-sensor based on synthetic ligand-coated CdTe quantum dots for rapid detection of Cr(III) ions in water and wastewater samples

In this study, a facile method was introduced for preparation of a ligand-coated CdTe QDs (CdTe-L QDs) for applying as a new optical nano-sensor in determination of Cr3+ ions in aqueous solutions. The prepared CdTe-L QDs were characterized using different analytical techniques including transmission electron microscopy (TEM), UV-Vis, thermogravimetric (TG) analysis, Fourier-transform infrared (FTIR), and fluorescence spectroscopies. It was found that the fluorescence intensity of the CdTe-L QDs at 540 nm (excitation at 380 nm) was selectively quenched in the presence of trace amounts of Cr3+ ions in comparison to different metal ions. In other word, a simple, highly sensitive, selective, and rapid analytical approach was used for the determination of Cr3+ ions in the concentration range of 6.78 +/- 0.05 x 10(-8)-3.70 +/- 0.02 x 10(-6) mol L-1 with a detection limit of 20.30 +/- 0.03 x 10(-9) mol L-1. Furthermore, the designed nano-sensor was well used for the quantification of Cr3+ ions in real samples with satisfactory analytical results, and the results were compared with the standard methods (inductively coupled plasma emission spectroscopy (ICP-OES)).