Abstract
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•Fluorescein/Thiourea is a highly and sensitive a colorimetric sensor for detection Hg2+ in aqueous solution.•The colorimetric method based on a colored complex formation between Fluorescein/Thiourea (FLTU) and Hg2+ ions.•The addition of Hg2+ ions quenched the fluorescence of fluorescein/Thiourea (FLTU) sensor.•Results are a highly sensitive method for detection in environmental water sample.
A simple and selective colorimetric method was used for detection of mercury ions (Hg2+) in the aqueous medium and environmental water sample. Fluorescein-thiourea (FLTU) conjugate complex as receptor was prepared by 1:1 M ratio of 10 µmol L−1 fluorescein dye and thiourea in phosphate buffer solution at pH 7.00. The IR spectra of FLTU receptor have illustrated the formation of H-bond between thiourea and fluorescein dye. The receptor fluorescein-thiourea (FLTU) was used as a chemo-sensor highly selectively to detect the Hg2+ ion by changing the receptor color from a yellow color to red through the quenching of fluorescence intensity of the receptor. The lower detection limit (LOD) and quantitation limit (LOQ) of Hg2+ ions with the receptor FLTU are 0.24 and 0.73 nmol L–1 (correlation coefficient R2 = 0.985) as determined through the absorption spectroscopic method, respectively. The mercury ions are promising and could be achieved via the formation of the complex in a 1:1 stoichiometric ratio of receptor to Hg2+ ions.