The changing impact of the collision-induced decomposition of ions on mass spectrometry

Abstract

The first observations of the products of the collision-induced decomposition (CID) of ions were made in the early days of the development of mass spectrometry and for many years, they were regarded as little more than a nuisance. Early in the 1960s, systematic work on CID began, and, although it proved to be very useful in the investigation of the structures of ions, in general, the mass spectrometry community regarded CID as a subject for fundamental studies but of little value in analytical work. In essence, CID was a technique looking for a problem. With the advent of soft ionisation methods, first fast atom bombardment and later electrospray ionisation and matrix-assisted laser desorption ionisation, all of which gave molecular weight information but no structural information, the situation changed, and CID became an integral part of analytical mass spectrometry. High-performance, compact tandem mass spectrometers based on the quadrupole, time-of-flight and ion trap mass analysers play an increasingly important role in biological mass spectrometry and Fourier transform ion cyclotron resonance instruments provide very-high-resolution CID capabilities. Tandem mass spectrometry is already the method of choice for the sequencing of proteins and will undoubtedly be important in helping us understand protein function.