Abstract: CdS quantum dots were synthesized in aqueous solution by using mercaptoethylic acid as the stabilizer and surface-modification reagent. The 512.4 nm fluorescence emission which was caused by the cavity-electron recombination on surface trap of CdS quantum dots was quenched in the presence of hemin. The quenching mechanism was a dynamic process based on electron transfer between Fe²⁺ of hemin and cavity of CdS quantum dots. Under optimal conditions, a concentration of 5.0×10^-6－25.0×10^-6 g/mL of hemin could be determined on the basis of the decrease ratio of fluorescence intensity of CdS quantum dots, with a detection limit of 3.35×10^-8 g/mL. The proposed method was utilized to analyze the blood serum sample in which hemin was added with satisfactory results.

Key words: CdS quantum dots, hemin, electron transfer, fluorescence quenching