Turkish Journal of Chemistry




A new approach based on a selective charge transfer reaction with alizarin red S is described for the simultaneous determination of azithromycin and levo oxacin in their binary mixtures using an absorption-factor spectrophotometric method. Native absorbance was used for the determination for levo oxacin, while a charge transfer complexation of alizarin red S served as the basis for the quantitation of azithromycin. The reaction of azithromycin with alizarin red S was possible in methanol under neutral conditions within 15 min at 25 ℃. The conditions were suitably optimized for selective complexation of azithromycin with minimal interference from levo oxacin. The calibration curve was linear over the concentration range of 4.0–20 𝜇g mL−1 for azithromycin and levo oxacin and the correlation coefficients of the regression equations were consistently greater than 0.9970 for both the drugs. The limit of detection was 1.07 𝜇g mL−1 for azithromycin and 0.84 𝜇g mL−1 for levo oxacin. The developed method was highly reproducible with precision (RSD%) values in the range of 0.54%–0.95% for both the drugs. The method was successfully applied for the simultaneous determination of these antibacterial drugs from their synthetic mixtures and pharmaceutical formulations with no interference from excipients.


Absorption-factor method, azithromycin, levo oxacin, alizarin red S, charge transfer complexation

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