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.