Improvement using chemometrics in ion mobility coupled to mass spectrometry as a tool for mass spectrometry fragmentation studies: flavonoid aglycone cases.

A chemometric method for the treatment of ion mobility coupled to mass spectrometry (IMS/MS) data is proposed as a complementary tool for obtaining experimental evidence for the study of MS fragmentations, which can provide a direct and automatable methodology for characterising ionic series and the hierarchy of all product ions of an MS spectrum. Two MS/MS with ion mobility experiments have been designed: in the first, the intrinsic mobility of each ion is estimated, and in the second experiment, distributions of the ionic intensity of product ions fragmented after IMS separations are recorded. These mobilograms are aligned using the coshift algorithm and mathematically fitted using Classical Least Squares (CLS) to determine the mobility contributions from their precursor ions. Despite some limitations when studying low intensity ions and ions with similar ion mobility, CLS fitting improves the usage of IMS coupled with accurate mass spectrometry as a complementary tool in the study of MS fragmentation mechanisms and more notably, it offers an automatable and efficient alternative to MS3 experiments.