LIQUID-CHROMATOGRAPHY ELECTROSPRAY TANDEM MASS-SPECTROMETRY OF AMINO-ACID CONJUGATES OF JASMONIC ACID UNDER POSITIVE AND NEGATIVE IONIZATION

The positive and negative ion electrospray mass spectra of a series of (N)-jasmonoyl amino acid conjugates were measured by combined high pe rformance liquid chromatography (HPLC)/mass spectrometry (MS), The mas s spectra obtained of both positive and negative ions exhibit mostly a single abundant peak of [M + H](+) and [M - H](-), respectively, whic h indicates the molecular mass of the conjugate, From these ions detai led structural information can be obtained by liquid chromatography/ta ndem mass spectrometry. The positive daughter ion mass spectra obtaine d by collision-induced dissociation (CID) of [M + H](+) give informati on about both the jasmonoyl moiety and the amino acid component. The n egative ion daughter spectra of [M - H](-) are dominated by an ion ori ginating from the deprotonated amino acid. Therefore, the conjugating amino acid can structurally be assigned by both the positive and negat ive ion CID mass spectra.