Determination of the Related Substances in Azithromycin Tablet by HPLC-Electrochemical Detector

OBJECTIVE: To determine the content of the related substances in azithromycin tablet by HPLC-electrochemical detector.METHODS: The column was Gamma ARP-1/P.The mobile phase consisted of 0.014 mol·L-1 dipotassium hydrogen phosphate/0.020 mol·L-1 sodium hydroxide(pH was adjusted to 11 by phosphoric acid and sodium hydroxide)-acetonitrile(71∶29) at a flow rate of 0.7 mL·min-1.The column temperature was 40 ℃.The injection volume was 50 μL.Glass carbon working electrode was set at +900 mV.RESULTS: The linear ranges of erythromycin peroxide,deoxyazithromycin,azithromycin impurity A,and N-demethlation azithromycin were 0.15～1.80 μg(r=0.999),0.09～1.08 μg(r=0.999),0.23～2.76 μg(r=0.998) and 0.30～3.60 μg(r=0.998),respectively.The average recoveries were 98.9%(RSD=1.1%),94.6%(RSD=5.4%),103.4%(RSD=3.4%) and 96.2%(RSD=4.3%),respectively.The contents of the related substances were all below 0.7%.CONCLUSION: The established method is reproducible,sensitive and reliable,and applicable for the detection of the related substances in azithromycin tablets.