In this study, a new method based on the HPLC online scavenging diphenyl-1-picrylhydrazyl (DPPH) radical activity and Q-TOF/MS for the rapid screening and identification of caffeoylquinic acids in Jerusalem artichoke, and its antioxidant activity was evaluated. The mobile phase was acetonitrile-0.1% formic acid aqueous solution (gradient elution), and the samples were separated by C18
column. The samples were mixed with DPPH radical solution in PEEK tube and then entered UV detector, the detection wavelength were 280 and 517 nm, and the online screening of caffeoylquinic acid components was realized by the negative peak generated at 517 nm. Results showed that, under the negative ion mode, according to the precise molecular weight combined with the standards, five antioxidant compounds were screened from the Jerusalem artichoke, including chlorogenic acid, caffeic acid, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid. The free radical scavenging rate of each component to DPPH, ABTS+
and superoxide anion was in the range of 54.63%~95.43%, 8.32%~69.63%, 27.37%~51.40%, and were positively correlated with the concentration. In this study, the caffeoylquinic acids in Jerusalem artichoke were rapidly identified and their antioxidant activities were explored, which provided a scientific basis for the development and utilization of caffeoylquinic acids in Jerusalem artichoke.