Fluorescent Determination of Hg2+ in Water and Fish Samples Using a Chemodosimeter Based in a Rhodamine 6G Derivative and a Portable Fiber-Optic Spectrofluorimeter

A fluorimetric chemodosimeter (FC1), based on a Rhodamine 6G derivative, is proposed for the recognition of Hg2+ ions in water and fish samples. The reagent shows a highly selective and sensitive reaction with Hg2+, giving rise to strong fluorescence emission at 555 nm. The obvious color change of the solution from colorless to pink upon the addition of Hg2+ demonstrates that FC1 can be used for "naked-eye" detection of Hg2+ in water effluents. The fluorescence intensity is proportional to the amount of Hg2+ at ng mL(-1) levels, and it is capable of distinguishing between safe and toxic levels of inorganic mercury in drinking water and fish samples. The procedure has been implemented in a portable instrument composed of a 515 nm light-emitting diode (LED) excitation source, two fiber optics, and a charge-coupled device (CCD) camera as detector, connected to a portable computer for data acquisition and analysis, intended for in situ determination of mercury, offering a viable alternative to a conventional spectrofluorimeter. The proposed method has been applied to different water and fish samples with satisfactory results.