Azithromycin is a 15-membered ring macrolide antibiotic. According to the United States Pharmacopeia and the National Formulary (USP 42-NF 37*), analysis of azithromycin injection should be carried out with a column and its guard column filled with L67 packing material and meets following requirements. The Asahipak ODP-50 4D and ODP-50G 4A (guard column) confirmed the requirements were met.

System suitability requirements:
　Resolution of azithromycin and azaerythromycin A: ≥ 2.5
　Relative standard deviation (RSD): ≤ 2.0 %
　Tailing factor of azithromycin: 0.9 to 1.5

*The version at the time of the application acquisition.  


Sample : 15 μL
1. Azaerythromycin A 1 mg/mL
2. Azithromycin 1 mg/mL
dissolved in H₂O/CH₃CN=48/52

Column       : Shodex Asahipak ODP-50G 4A (4.6 mm I.D. x 10 mm) 
               + ODP-50 4D (4.6 mm I.D. x 150 mm)
Eluent       : 6.7 g/L Dibasic potassium phosphate aq./CH3CN=48/52
               (adjusted to pH 11.0 with 10 M KOH aq.)
Flow rate    : 1.0 mL/min
Detector     : UV (215 nm)
Column temp. : 40 °C