Waridel P Wolfender JL Ndjoko K Hobby KR Major HJ Hostettmann K 2001 LC-MS-MS is becoming a very important tool for the on-line identification of natural products in crude plant extracts. For an efficient use of this technique in the dereplication of natural products, a careful study of the parameters used to generate informative MS-MS spectra is needed. In this paper, the collision-induced dissociation (CID) MS-MS spectra of ubiquitous C-glycosidic flavonoids have been systematically studied using hybrid quadrupole time-of-flight and ion-trap (IT) mass analysers under various CID energy conditions. Efficient differentiation of flavonoid C-glycoside isomers was possible, based on the comparison of CID-MS-MS spectra of particular C-glycoside unit fragments. Striking differences between 6-C and 8-C flavonoid glycosides were especially observed in the product ion spectra of their 0.2X+ fragments ([M+H-120]+). Some guidelines for the on-line characterisation of C-glycosidic flavonoids by LC-MS-MS or LC-multiple-stage MS are given. https://sonar.ch/global/documents/189570 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/s0021-9673(01)00806-8 info:eu-repo/semantics/altIdentifier/pmid/11554416 Journal of chromatography. A. - 2001 Flavonoids Glycosides Isomerism Mass Spectrometry Evaluation of quadrupole time-of-flight tandem mass spectrometry and ion-trap multiple-stage mass spectrometry for the differentiation of C-glycosidic flavonoid isomers. http://purl.org/coar/resource_type/c_6501