A commercially-available sulfonphthalein derivative was demonstrated to be a chemodosimeter for Fe2+ and its sensing behavior was further investigated by UV-vis spectroscopy in aqueous media under the optimum conditions.In the presence of chlorophenol red (CPR) and H2O2,the absorption maximum at 435 nm decreased upon addition of Fe2+,resulting in a significant color change of the CPR solution from yellow to colorless.The chemosensor system did not show significant responses to a series of other metal ions including Al3+,Zn2+,Cd2+,Hg2+,Mn2+,Co2+,Fe3+,Ni2+,Cu2+,La3+,Ce4+,Th4+,Pd2+,Pb2+,Sb3+,Cr3+,Au3+,Ag+,Nd3+,Sm3+,alkali and alkaline earth metal cations,allowing for highly selective naked-eye detection of Fe2+.Quantitative analysis was carried out kinetically for practicable the Fe2+ assay when either fixed time method or the initial rate method was applied.When the detecting time was set,the decrease of absorbance signal was linear with Fe2+ concentration in the range of 0 to 7.50 × 10-5 mol L-1 and the regression equation was ΔA = 0.00759 + 0.00593CFe with a correlation coefficient r = 0.9953.The chemodosimetric system has employed an irreversible Fenton reagent-promoted oxidation of the CPR free chromophore and the hydroxyl radicals were generated in the presence of both Fe2+ and hydrogen peroxide.The mechanistic interpretation of the signaling process was partially confirmed by the radical scavenging experiment and the FT-IR analysis of the intermediates formed at different reaction periods. A commercially-available sulfonphthalein derivative was demonstrated to be chemodosimeter for Fe2 + and its sensing behavior was further investigated by UV-vis spectroscopy in aqueous media under the optimum conditions. In the presence of chlorophenol red (CPR) and H2O2, the absorption maximum at The chemosensor system did not show significant responses to a series of other metal ions including Al3 +, Zn2 +, Cd2 +, Hg2 +, Mn2 +, Co2 + , Fe3 +, Ni2 +, Cu2 +, La3 +, Ce4 +, Th4 +, Pd2 +, Pb2 +, Sb3 +, Cr3 +, Au3 +, Ag +, Nd3 +, Sm3 +, alkali and alkaline earth metal cations, allowing for highly selective naked-eye detection of Fe2 + carried out kinetically for practicable the Fe2 + assay for either fixed time method or the initial rate method was applied. When the detection time was set, the decrease of absorbance signal was linear with Fe2 + concentration in the range of 0 to 7.50 × 10 -5 mol L -1 and the regression equation was ΔA = 0.00759 + 0.00593 CFe with a correlation coefficient r = 0.9953. The chemodosimetric system had employed an irreversible Fenton reagent-promoted oxidation of the CPR free chromophore and the hydroxyl radicals were generated in the presence of both Fe2 + and hydrogen peroxide. The mechanistic interpretation of the signaling process was partially confirmed by the radical scavenging experiment and the FT-IR analysis of the intermediates formed at different reaction periods.