RESUMO
OBJECTIVE: To detect whether there is mixing of norfloxacin in loperamide hydrochloride capsules by UPLC-MS. METHODS: The separation of norfloxacin was performed on C18 column with column temperature set at 35 ℃, and the mobile phase was composed of acetronitrile and 0.1% formic acid (gradient elution) with a flow rate of 0.3 mL?min-1. The sample size was 10 ?L. ESI source was applied with capillary tube tension at 3.0 kV and ion source temperature at 110 ℃, and scan mode was multiple reaction monitor. RESULTS: It has been proved that there was norfloxacin in 2 of the total 5 batches of samples based on the data of retention time of RP-HPLC including ultraviolet spectra, the quasi-molecular ion and the second order mass spectra split fragments. CONCLUSION: The method is highly selective and sensitive, and can be used to detect whether norfloxacin has been illegally added into loperamide hydrochloride capsules.