Mass spectra of methyl abscisate and isotopically labelled analogues

Abstract

Metastable analysis, isotopic labelling, and high resolution measurements were used to study the cracking patterns of methyl abscisate. Ten labelled analogues of methyl abscisate and methyl 2-trans-abscisate were available for this purpose. The principal fragmentation pathway involves ions at m/e 222, 190, 162, 134, 106, and 91, and specific labelling of each oxygen atom with oxygen-18 proved especially helpful in defining the structures of the intermediate ions. Other important fragmentations of the molecular ion are the loss of methanol, the loss of water, and the cleavage of the complete side chain to give the abundant ion at m/e 125.