RESONANCE RAYLEIGH SCATTERING STUDY OF STREPTOMYCIN - CONGO RED IONIC ASSOCIATION IN VIEW OF ANALYTICAL APPLICATION

Streptomycin (STR) and Congo red (CR) react in weak acidic medium to give an ionic association complex which was studied by resonance Rayleigh scattering (RRS) and UV-VIS absorption. The combinative sites were defined by calculating the charge distribution on the STR and CR molecules in the ground state using Austin Model 1 quantum chemistry method. The maximum intensity of RRS signal (384 nm) was obtained at pH 5.5 created with Britton-Robinson buffer at a 2-10(-8)M Congo red concentration; the reaction time was of 30 minutes. The ratio of the reagents (1:1) was determined using Job's method. The linear relationship between the RRS intensity and the antibiotic concentration was found within the concentration range 6.49 - 9.74 mu g.mL(-1). The method was successfully applied for the determination of streptomycin in pharmaceutical formulations.