Time is an important factor in physical and natural sciences. It characterizes the progress of chemical and biochemical processes. Mass spectrometry provides the means to study molecular structures by detecting gas-phase ions with the unique mass-to-charge ratios. Time-resolved mass spectrometry (TRMS) allows one to differentiate between chemical states that can be observed sequentially at different time points. Real-time mass spectrometric monitoring enables recording data continuously with a specified temporal resolution. The TRMS approaches - introduced during the past few decades - have shown temporal resolutions ranging from hours down to microseconds and beyond.
This text covers the key aspects of TRMS. It introduces ion sources, mass analyzers, and interfaces utilized in time-resolved measurements; discusses the influence of data acquisition and treatment; finally, it reviews most prominent applications of TRMS - in the studies of reaction kinetics and mechanism, physicochemical phenomena, protein structure dynamics, biocatalysis, and metabolic profiling.
It will assist science and engineering students to gain a basic understanding of the TRMS concept, and to recognize its usefulness. In addition, it may benefit scientists who conduct molecular studies in the areas of chemistry, physics and biology.

Pawel Urban is an Assistant Professor in the Department of Applied Chemistry at National Chiao Tung University, Taiwan. He studied his MISMaP MSc, in biology at the University of Warsaw, Poland between 1999 & 2002. He then studied at the University of York UK, between 2004 & 2007 where he gained his PhD, in Chemistry. He began working as a postdoctoral Assistant in the Faculty of Biology, University of Warsaw, before moving to Swiss Federal Institute of Technology (ETH), Zurich and 2 years later to National Chiao Tung University, where in both institutes he?worked as a PDRA, before beginning his current role of Assistant Professor.

Yu-Chie Chen is a Professor of Chemistry in the Department of Applied Chemistry, National Chiao Tung University, Taiwan. She obtained her Bachelor degree at Kung University, Taiwan, her Masters at Sun Yat-sen, Taiwan and her P.h.D at Montana State University, USA. Before working at National Chiao Tung University, she held positions at Swiss Federal Institute of Technology Zurich, Tzu Chi Medical and Tzu Chi University.

Yi-Sheng Wang is an Associate Research Fellow at the Genomics Research Center, Academia Sinica, Taiwan. He acheived his Chemistry Ph.D. at the National Taiwan University, in 2001. Between 2001 & 2005, he began working as a?Postdoctoral Fellow, at the Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, (including a Postdoctoral Fellow at?National High Magnetic Field Laboratory (NHMFL), Florida State University, U.S.A. between 2002-2003). In 2005, he moved to the Genomics Research Center, Academia Sinica, Taiwan, as a Assistant Research?Fellow, until 2011, when he was promoted to?his current position of Associate Research Fellow.