Environmental molybdate monitoring based on vanadium oxide quantum dots-derived fluorescent strategy

The detection of molybdate (MoO42- ) is of great significance in environmental area since the high concentration will cause poison to animals, plants and human body. Fluorescent assays were considered as a promising analytical strategy due to its high sensitivity, wide linear range and so on, but were rarely reported because of the lack of selective probes. Considering the electron transfer between MoO42- and vanadium, vanadium oxide quantum dots (VOx QDs) were designed as fluorescent probes for selective and sensitive detection of MoO42- in aqueous samples. Such VOx QDs exhibit uniform dispersion, narrow size distribution and about average diameter of 3.09 +/- 0.14 nm. Under the optimized conditions, the relationship between fluorescence (FL) intensity and MoO42- anion concentrations were linear in the range of 2-300 mu M (R2 = 0.990) and 400-800 mu M (R2 = 0.988) while the lowest limit of detection was 1.5 mu M MoO42- . Especially, the as-proposed assay can efficiently avoid the interference of almost all the anions and cations commonly existing in the environment. More importantly, the VOx QDs-based fluorescent sensing method was successfully applied to the assays of MoO42- in river and lake water samples.