Resonance Rayleigh scattering spectra of interaction of aminoglycoside antibiotics with trypan red and their analytical applications

In weak acid medium, some aminoglycoside antibiotics, such as kanamycin (KANA), gentamicin (GEN), tobramycin (TOB) and neomycin (NEO), or acid bisazo dye trypan red (TR) alone can only produce very weak resonance Rayleigh scattering (RRS) signals. However, when one of the antibiotics and TR react with each other to form the ion association complexes, the RRS intensity can be enhanced greatly and a new RRS spectrum and a significant enhancement of the RRS intensity in the wavelength range from 400 to 535 nm can be observed. The maximum scattering peak is at 400 nm and there is a linear relationship between the RRS intensity and the antibiotics concentration in the range of 0.013 similar to 6.0 mug (.) mL(-1). An RRS method for the determination of aminoglycoside antibiotics at trace amounts of levels has been developed. The detection limits (3sigma) of the four antibiotics, whose order of sensitivity from high to low ranks as KANA > NEO > TOB > GEN, are 12.9 similar to 17.6 ng (.) mL(-1). This method has good selectivity and has been successfully applied to the quick determination. of antibiotics not only for injections and ear drips, but also for clinic serum samples as well. In addition, the reaction mechanism by using quantum chemistry method and the influencing factors of the RRS spectra and the enhancement reasons of RRS have been discussed.