Design and performance of an atmospheric pressure ion mobility Fourier transform ion cyclotron resonance mass spectrometer.

This manuscript presents our initial results and development of a novel hybrid instrument that combines atmospheric pressure ion mobility spectrometry (AP-IMS) with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). Our preliminary results obtained from atmospheric pressure mobility separation of peptide mixtures combined with high-resolution FTICR mass analysis are demonstrated. The custom IMS system was constructed in-house and was coupled to the commercial FTICR-MS instrument through a flared inlet capillary interface. Dual-gate ion filtration was adapted to allow concurrent measurement of both mobility and m/z values. The feasibility of mobility separation was demonstrated with baseline separation of the peptides bradykinin and angiotensin II and their measured reduced mobility constants which were consistent with those previously reported. Furthermore, the unique size-to-charge separation mechanism of IMS that allows isomer separation was explored and demonstrated with the partial separation of two isomeric phosphopeptides. We feel the combination of IMS and FTICR-MS holds great potential for accurate mass analysis of mobility-selected ions and these results are the first to demonstrate the feasibility of coupling these two techniques.