Ion-Molecular Reactions of Esters of Carbocyclic Alcohols in a Direct Analysis in Real Time (DART) Mass Spectrometer

We studied the interaction of acyl derivatives of carbocyclic alcohols of steroid structure with nitrogenous bases in the ion source of a “direct analysis in real time” (DART) mass spectrometer. The protonation of esters in the DART plasma is accompanied by the elimination of a corresponding acid (acyl derivatives of cholesterol, β-sitosterol, and estradiol), interaction of the formed cation with a nitrogenous base to yield a derivative with a bound charge. This effect was not observed for cortisone acetate and betamethasone dipropionate, which is consistent with the absence of ions of deacyl derivatives in their DART mass spectra.