Detection of phosphate based on phosphorescence of Mn doped ZnS quantum dots combined with cerium(iii)

Abstract

A simple and rapid room-temperature phosphorescence (RTP) sensor for phosphate detection was developed on the basis of Ce³⁺ modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs). This sensor utilizes the affinity of lanthanides-phosphates and the RTP properties of doped QDs. Ce³⁺ can electrostatically interact with carboxyl groups on the surface of MPA-capped Mn-doped ZnS QDs, which leads to the aggregation of QDs and changes the RTP signals. The high affinity of phosphate to Ce³⁺ enables the dissociation of Ce³⁺ from the surface of MPA-capped ZnS QDs, forming a stable complex with phosphate and recovering the RTP of the QDs. Under the optimized conditions, the phosphate detection range is 8 to 320 μM (R = 0.9998) and the detection limit is 2.71 μM. Thus, the new sensor is potential for phosphate detection in environmental water without complicated pretreatment and is free from the interference of background fluorescence or scattering light.