Determination of chromium(III) in aqueous solution using CePO4 :Tb(3+) nanocrystals in a fluorescence resonance energy transfer system.

Trivalent chromium is an essential element required for normal carbohydrate, lipid and protein metabolism in humans and animals. This article describes an efficient fluorescence resonance energy transfer (FRET) system between CePO4 :Tb(3+) nanocrystals as the donor and chromium(III) as the acceptor. CePO4 :Tb(3+) nanocrystals were synthesized in aqueous solution, and characterized by transmission electron microscopy. Under optimum conditions, a linear calibration graph was obtained (R(2)  = 0.996). The linear range and detection limit of chromium(III) were 0.01-2.2 μM, and 9.1 nM, respectively. The proposed method had a wide linear range and proved to be very sensitive, rapid and simple. Moreover, the method was applied successfully to the determination of chromium(III) in synthetic samples and tap water.