Aqueous synthesis of L- methionine capped PbS quantum dots for sensitive detection and quantification of arsenic (III)

Abstract

A simple aqueous chemical approach was employed for the synthesis of the PbS quantum dots (QDs) using L-methionine (Meth) as the capping agent. The as-synthesized Meth-capped PbS QDs exhibited size-uniform, strong fluorescence emission (maximum emission at 510 nm) with 17.3 % quantum yield (QY) and robust photo- and time-stability. The resulting PbS QDs acted as a fluorescent probe for selective detection of As(III) in aqueous media. When As(III) ions were added to the QDs solution, the fluorescence intensity was effectively quenched, due to strong interaction between As(III) and Meth to form an S, N bidentate chelate ring. Under optimum conditions, a linear relationship between fluorescence quenching of the system and the concentration of As(III) was observed in the range of 5–150 ppb with a limit of detection of 3.7 ppb. It was less than the highest tolerable amount of As(III) ions (10 ppb) in drinking water, which is allowed by the World Health Organization (WHO). This proposed fluorescent method possesses good selectivity and high sensitivity, which can be applied in the rapid detection of As(III) in real water samples.