Determination of iron(III) based on the fluorescence quenching of rhodamine B derivative.

A new method for determination of iron(III) has been developed using a kind of rhodamine B derivative fluorescent probe, rhodamine amide (RHA), in acidic HAc-NaAc buffer solution. In this approach, the heavy atom effect of I₃(-) was applied to quench the fluorescence of RHA. When iron(III) and KI coexisted in HAc-NaAc buffer solution, iron(III) reacted with the excess KI to produce I₃(-) that quenched the fluorescence of RHA through the formation of a non-fluorescence compound. The results showed that the fluorescence intensity decrease of RHA presented a good linear relationship with the iron(III) concentrations in the range from 0.5 to 5.0 μmol L(-1) with the correlation coefficient of 0.9970, and the detection limit was 0.3 μmol L(-1) iron(III). The approach was applied to determination of iron(III) in water samples, and the recovery was found to be from 80.7% to 100. 8%.