Mass Spectral Investigations on Toxins. 5. Direct Analysis of Macrocyclic Trichothecenes in Fermentation Samples by Negative Ion Tandem Mass Spectrometric Techniques

摘要

Due to the extended conjugation in the molecules, macrocyclic trichothecenes formed negatively charged molecular (M) ions more effectively than positively charged quasi molecular ions under chemical ionization (Methane) conditions. These M ions underwent collisionally activated dissociation (CAD) (argon) yielding the daughter ions characteristic of the macrocyclic ester bridges. Structures for various specific and abundant daughter ions have been proposed; and the daughter ions and experimental conditions for selectively detecting these trichothecenes have been selected. A semisynthetic, macrocyclic trichothecene has been found to be adequate as an internal standard for quantifying macrocyclic trichothecenes under CAD conditions. Low quantities (1 to 2 ng) of Roridin H and Satratoxins have been detected under these same conditions. Preliminary results indicate that the negative ion chemical ionization-mass spectrometry/mass spectrometry method can be applied to analyzing real-life samples.