Selective colorimetric and fluorescent quenching determination of uranyl ion via its complexation with curcumin

• We performed a fluorescence quenching assay of toxic UO22 + in water solution.
• Natural pigment curcumin and Triton X-100 micelles was used as probe.
• The LOD was about 9000 times lower than the maximum allowable level given by WHO.
• The reaction mechanism was explored.

Under pH 4.0 HAc–NaAc buffer medium, curcumin alone possesses extraordinary weak fluorescence emission. Nevertheless, the introduction of Triton X–100 micelles can largely enhance the fluorescence intensity of curcumin. Uranyl ions can complex with micelles–capped curcumin, along with the slight red shift of curcumin fluorescence (about 1–7 nm), a clear decrement of absorbance (424 nm) and fluorescence (507 nm) intensities, and a distinct color change from bright yellow to orange. The fluorescence decrements (ΔF, 507 nm) are positively correlated to the amount of uranyl ions in the concentration range of 3.7 × 10− 6–1.4 × 10− 5 mol L− 1. The detection limit of this fluorescence quenching methods is 3.7 × 10− 6 mol L− 1, which is nearly 9000 times lower than the maximum allowable level in drinking water proposed by World Health Organization. Good selectivity is achieved because of a majority of co–existing substances (such as Ce4 +, La3 +, and Th4 +) do not affect the detection. The content of uranyl ions in tap water samples was determined by the proposed method with satisfactory results.

A simple, sensitive and selective assay was established to detecting toxic UO22 + by quenching the enhanced fluorescence of curcumin in Triton X-100 micelles.Figure optionsDownload as PowerPoint slide