Retention of Macrolide Antibiotic

Azithromycin has weak UV absorbance and typical asymmetric peak profile with low Column efficiency in many HPLC-UV methods.  This ELSD Method shows good retention and peak shape along with excellent sensitivity.  This method is very reproducible with %RSD values less than 0.1%, as shown in the 10 injection overlay below.


Method Conditions
Column: Cogent Bidentate C8™, 4µm, 100Å
Catalog No.: 40008-10P
Dimensions: 4.6mm x 100mm
Mobile Phase:
A: Isopropanol

B: Acetonitrile  / 0.1% Triethylamine (TEA) (v/v)

Time (minutes) %B
0 100
1 100
2 85
3 85
4 100
5 100

Flow rate: 1.0 mL/minute
Detection: ELSD (Evaporative Light Scattering Detector) Gain: 9; Temperature: 80°C;
Injection vol.: 1μL
Sample Preparation: Reference standards (1 mg/mL) in diluent of 50:50 Acetonitrile / DI Water (v/v)
t01.50 Minutes
K’: 2

Note: Azithromycin is a semi-synthetic macrolide Antibiotic of the Azalide class. Azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit of the bacterial 70S ribosome. 

Note 2: Capacity is determined using the following equation: k = (tR-tO)/tO

  • tR = Retention Time of an Analyte Peak
  • tO = Retention Time of non-Retained Peak