Abstract: OBJECTIVE To establish LC-MS/MS method for the determination of anililines genotoxic impurities (6-aminoquinoxaline, 4-nitro-o-phenylenediamine, and 6-amino-5-bromoquinoxaline) in brimonidine tartrate. METHODS The method was achieved on a ZORBAX Eclipse Plus C₁₈ column(2.1 mm×50 mm, 1.8 μm) utilizing a mobile phase of 0.1% acetic acid(A)-acetonitrile(B) with gradient elution at the flow rate of 0.35 mL·min^-1. The temperature of column was set at 35℃. The Shimadzu LC30 UPLC-AB Science 4000+ LC-MS was used to detect(ESI source) in multiple reaction monitoring positive mode. RESULTS The calibration curves of 6-aminoquinoxaline, 4-nitro-o-phenylenediamine, 6-amino-5-bromoquinoxaline were linear in 9.98-199.50, 9.94-198.74, 10.03-200.55 ng·mL^-1. The average recoveries of the control samples at low, middle and high concentrations(50, 100, 150 ng·mL^-1) were 94.8%-110.8%, all RSDs were <4.2%, solution stability was good within 12 h. CONCLUSION The method is convenient to operate and has reliable results for the determination of anililines genotoxic impurities of 6-aminoquinoxaline, 4-nitro-o-phenylenediamine, 6-amino-5-bromoquinoxaline in bromnidine tartrate.