Gas chromatographic–mass spectrometric determination of azithromycin in biological fluids

Azithromycin monohydrate is an antibiotic, which belongs to the category of macrolide antibiotics. It is used for an effective antibiotic for the treatment of sexually transmitted diseases, upper and lower respiratory tract infections and skin structure infections. A gas chromatographic–mass spectrometric (GC–MS) method is described for the determination of azithromycin monohydrate residue in biological fluids. This method allows detection of residual azithromycin (AZM) in biological fluids by using single-ion monitoring (SIM). The confirmation by a full-scan electron impact (EI) mass spectrum is possible if residual level in a sample is >5 μg/mL. AZM is extracted with chloroform from a sample and cleaned up by n -hexane washing followed by partition between chloroform and phosphate buffer solution. The cleaned up extract is acetylated in acetic anhydride–pyridine mixture (1:2) at room temperature. The reaction mixture is injected into the GC–MS apparatus, and the detection has been conducted using SIM at m / z 200. The detection limit is 2 μg/mL. This proposed method could be successfully applied to the drug analysis in the forensic laboratories as well as in the toxicological laboratories.