In about pH 2.5 weakly acidic medium, congo red can react with an anthracycline anticancer drug such as epirubicin, daunorubicin or mitoxantrone. As a result, the spectra of absorption and fluorescence were changed a little, but the resonance Rayleigh scattering (RRS) was enhanced greatly, and a new RRS spectrum appeared. At the same time, their second-order scattering (SOS) and frequency doubling scattering (FDS) were also increased. The maximum RRS signals of three ion-association complexes were all located at about 370 nm, and there was another peak near 280 nm. Their maximum scattering peaks were at 530 for SOS and 353 nm for FDS, respectively. The sensitivity of RRS method was much higher than those of SOS and FDS. The detection limits for three drugs were 0.054 for epirubicin, 0.058 for daunorubicin and 0.033 mg/mL for mitoxantrone. There was a linear relationship between the RRS intensity and the drug concentration in the range of 0.05～12.0 for epirubicin, 0.05～12.0 for daunorubicin and 0.04～7.5 mg/mL for mitoxantrone, respectively. In this work, the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reaction and the properties of analytical chemistry were investigated. A sensitive, simple and new method for the determination of anthracycline anticancer drugs based on RRS has been developed.

Key words: resonance Rayleigh scattering, anthracycline anticancer drug, congo red