Electrospray ionization with ambient pressure ion mobility separation and mass analysis by orthogonal time-of-flight mass spectrometry

Rapid screening and identification of drug and other mixtures are possible using a novel ambient pressure high-resolution ion mobility (APIMS) orthogo nal reflector time-of-flight mass spectrometer (TOFMS). Departing ions from the APIMS drift tube traversed a pressure interface between the APIMS and TOFMS where they were subjected to numerous gas collisions that could produ ce selective fragmentation. By increasing the accelerating field in the pre ssure interface region, the ions generated using water-cooled electrospray ionization (ESI) underwent collision-induced dissociation (CID). Mixtures o f ESI ions were separated by APIMS based on their respective size-to-charge (s/z) ratios while CID and analysis of mass-to-charge (m/z) ratios occurre d in the pressure interface and TOFMS. Product ions that were formed in thi s pressure interface region could be readily assigned to precursor ions by matching the mobility drift times. This process was demonstrated by the exa mination of a mixture of amphetamines and the resulting fragmentation patte rns of the mobility-separated precursor ion species [M + H](+). Copyright ( C) 2001 John Wiley & Sons, Ltd.