Fluorescence determination of Fe(iii) in drinking water using a new fluorescence chemosensor

Abstract

A new fluorescence chemosensor based on (Z)-2-(1-(3-oxo-3H-benzo[f]chromen-2-yl)ethylidene)hydrazine-1-carbothioamide (CEHC) has been developed for the determination of Fe(III) in drinking water. The optimum conditions were acetate buffer solution with a pH 5.0. In this approach, the determination of Fe(III) is based on static quenching of the luminescence of the probe upon increasing concentrations of Fe(III). The CEHC sensor binds Fe(III) in a 1 : 1 stoichiometry with a binding constant K_a = 1.30 × 10⁴ M⁻¹. CEHC responds to Fe(III) in a way that is more sensitive, selective, and quick to turn off the fluorescence than to other heavy metal ions. Selectivity was proved against seven other metal ions (Mn(II), Al(III), Cu(II), Ni(II), Zn(II), Pb(II), and Cd(II)). The calibration curve was constructed based on the Stern–Volmer equation. The linear range was 2.50–150 μM with the correlation coefficient of 0.9994, and the LOD was 0.76 μM. The method was successfully applied to determine Fe(III) in drinking water samples, and the accuracy of the chemosensor was validated by atomic absorption spectrometry.