OBJECTIVETo discuss mass spectrum characterization of five valepotriates including 'monoene' type (didrovaltrate), 'diene' type (valtrate, acevaltrate) and 'four-olefinic' type (baldrinal and homobaldrinal) by electrospray ionization tandem mass spectrometry (ESI-MS(n)).

METHODThis study was carried out on the basis of electrospray ionization tandem mass spectrometric method and analysis of multistage fragments.

RESULTThe fragmentation patterns and structural assignment of 'monoene' type, 'diene' type and 'four-olefinic' type valepotriates in ESI-MSn under positive mode were summarized.

CONCLUSIONThe compounds have a strong pyrolysis rules and it can provide reference date for valepotriates in rapid structural identification, quantitative analysis and pharmacokinetic study.