Fluorescence quenching method for the determination of bleomycins A 5 and A 2 with halofluorescein dyes

In weak acidic medium, the anticancer antibiotics bleomycin A 5 (BLMA 5 ) and bleomycin A 2 (BLMA 2 ) bind with halofluorescein dyes, such as erythrosin (Ery), eosin Y (EY) and eosin B (EB), to form ion‐association complexes, which causes fluorescence quenching of halofluorescein dyes. The quenching values ( ΔF ) are directly in proportional to the concentrations of bleomycins over the range 0.09–2.5 µg/mL. Based on this, a fluorescence quenching method for the determination of BLMA 5 and BLMA 2 has been developed. The dynamic range is 0.12–2.5 µg/mL for the determination of BLMA 5 and 0.09–2.0 µg/mL for BLMA 2 , with detection limits (3σ) of 0.04 µg/mL for BLMA 5 , 0.03 µg/mL for BLMA 2 , respectively. It has been applied to determine the two antibiotics in human serum, urine and rabbit serum samples. The recovery is in the range 90–102%. In this work, the optimum reaction conditions and the spectral characteristics of the fluorescence are investigated. The reasons for fluorescence quenching are discussed, based on the fluorescence theory. Copyright © 2007 John Wiley & Sons, Ltd.