Gas chromatographic/mass spectrometric analysis of methyl methanesulphonate and ethyl methanesulphonate in the bismesylate salt of DPI 201-106, a positive inotropic agent for the treatment of heart failure.

ABSTRACT

A gas chromatographic/mass spectrometric procedure using single-ion monitoring and repetitive scanning was developed to characterize and determine methyl methanesulphonate (MMS) and ethyl methanesulphonate (EMS) in the free base and bismesylate salt of DPI 201-106, a positive inotropic agent used in the treatment of heart failure. Mass spectral fragmentations, leading to product ions, are rationalized and mechanisms of potential rearrangement pathways are described. The apparent levels of MMS and EMS, as measured against the internal standard n-propyl methanesulphonate, were found to be 0.51 and 1.31 micrograms per gram of bismesylate salt, respectively. The presence of these alkylating agents in the free base was not observed.