IMS–MS studies based on coupling a differential mobility analyzer (DMA) to commercial API–MS systems

Recent progress in adding a mobility dimension to preexisting API–MS systems without modifying the MS itself is discussed, based on inserting a differential mobility analyzer (DMA) as part of the MS's atmospheric pressure ion source. Design criteria leading to high DMA resolving power R and transmission efficiency η are discussed. Various DMA prototypes have been interfaced to several triple quadrupoles, a single quadrupole and a quadrupole-TOF, all demonstrating R > 50 and η > 50%. We obtain two-dimensional DMA–MS spectra of the multiply charged clusters formed in electrosprays of concentrated solutions of tetrahexylammonium bromide (A+Br−). These reveal systematic loss of (ABr)A+ fragments from unstable multiply charged clusters, and provide mobility measurements in air on mass resolved (ABr)n(A+)z(ABr)n(A+)z clusters with n > 100 and z up to 10. Well-defined bands of ions not individually resolved are clearly visible at considerably larger n and z values.

Progress in adding a mobility dimension to preexisting API–MS systems is discussed, based on inserting a differential mobility analyzer (DMA) as part of the MS's atmospheric pressure ion source.Figure optionsDownload high-quality image (493 K)Download as PowerPoint slide