New Extractive Colorimetric Method for the Assay of Gentamicin and Streptomycin Using Ion-Pair Association Complexes

Abstract

Gentamicin and streptomycin aminoglycozide antibiotics, were determined using new selective
spectrophotometric methods based on the formation of stable ion association complexes with methyl
red dye in alkaline medium. These complexes can be extracted with chloroform at (pH = 8.5) after that
the absorbance of the colored complexes was measured at 490 nm. The methods were linear in the
concentration ranges of 15-60 and 18-75 with Limit of detection (LOD) of 9 and 13 µgmL-1
for
gentamicin and streptomycin respectively. The stoichiometry of the two ion pair complexes was
determined by the continuous variation method.