In Situ Formation of Quantum Dots as a Novel Fluorescence Probe for Phosphate Anion Detection

A new fluorescence detection method for PO43− was developed through the in situ synthesis of cadmium sulfide quantum dots (CdS QDs). Without PO43−, the CdS QDs could not be effectively formed by only the S2− and Cd2+ in the solution. As a stabilizer, PO43− is an essential component to regulate the in situ synthesis of CdS QDs. The fluorescence intensity following the addition of different concentrations of PO43− was monitored for quantification. Under optimum conditions, the fluorescence intensity shows a linear relationship with concentrations ranging from 3.0 to 300 µM, and a detection limit of 2.9 µM. This assay was successfully employed to assess PO43− in tap water and wastewater. Compared with traditional methods, which require pre-synthesizing QDs and tethering them with recognition elements to achieve sample detection, the proposed method is simpler and quicker. It takes less than 5 min to complete PO43− detection.