3. Results and discussion
3.1. Characters of the on-line HPLC-FRSD system
In this study, an on-line high performance liquid chromatography-free radical scavenging detection (HPLC-FRSD) system was developed. It consisted of a Waters e2695 HPLC system [a Waters quaternary pump system, a column oven, an autosampler, a Waters X-Terra MS C18 guard column and Waters 2998 photodiode array detector (PAD)] and a free radical scavenging detector system (peek reaction coil, temperature control model, pump and 2489 UV/Visible detector) (Fig. 1). The whole system was supported by Waters Empower TM 2 Chromatography Data Software (Waters Corporation, Milford, MA, USA).