Determination of Trace Iron in Chinese Herbal Medicine Using CdS Quantum Dots as Fluorescence Probes

A simple A green protocol for synthesis of high quality, water-soluble and biocompatible CdS QDs have been developed in aqueous solution with amylum as stabilizing agent. The QDs were characterized by AMF and spectral methods. A fluorescence quenching method was developed for determination of iron (ΙΙΙ) with water soluble CdS quantum dots (QDs) as fluorescence probe. In pH 8.5 boric acid–borax buffer solution, the QDs show a high selective to ferric ion. The common cations, such as Ca2+, Mg2+, Zn2+, Fe2+ et al, have no effect on interference but copper ion. The fluorescence intensity of the QDs decreased linearly with the iron (QDs ) concentration in the range of 200 μM to 60 nM with a detection limit of 20 nM. It has been applied to determinate of iron in Angelica, Astragalus, Shouwu, ligusticum wallichii and radix rehmanniae recen.