HPLC Determination of Azithromycin and Related Components with Electrochemical Detection

Azithromycin (AZMC) and related components i.e.,desosaminylazithromycin (DSMAZMC),azaerythromycin A (AZEMC-A) and N-demethylazithromycin (N-DMAZMC) in AZMC granules were determined simultaneously by HPLC with electrochemical detection (EC detection).The Thermo C18 column (150 mm×4.6 mm,5 μm) was used as the stationary phase for separation of the components with column temperature at 35 ℃.A mixture of 20 mmol·L-1 KH2PO4 solution (pre-adjusted to pH 7.37 with 1 mmol·L-1 KOH solution) and methanol (mixed in the ratio of 47 to 53 by volume) was used as the mobile phase with flow-rate of 1.0 mL·min-1.The EC detection was made at the potential of 1.05 V.Linear relationships between values of peak area and concentrations of the 4 components were obtained in the ranges of 37.06-593.0 mg·L-1 (for AZMC),2.63-84.00 mg·L-1 (for DSMAZMC),9.20-294.5 mg·L-1 (for AZEMC-A) and 6.69-107.0 mg·L-1 (for N-DMAZMC).Detection limits (3S/N) found for the 4 components were 9.28,1.32,4.60,3.35 mg·L-1,respectively.Tests for recovery were made by standard addition method,and values of average recovery obtained were 99.9%,100.6%,99.9% and 99.8% respectively.