Time‐of‐flight mass spectrometry

Abstract Time‐of‐flight (TOF) mass spectrometers have become the instruments of choice where high molecular masses must be measured. Pulsed extraction, orthogonal extraction, and reflectron designs have greatly improved mass resolution. In addition, hybrid and tandem instruments, such as quadrupole/TOF, ion trap/TOF, and TOF/TOF mass spectrometers now provide the opportunity for obtaining tandem mass spectra. Time‐of‐flight instruments are used in proteomics for determining the molecular weights of intact proteins, for accurate mass measurements of tryptic peptides (mass fingerprinting), for amino acid sequencing (sequence tags) and for determining the locations and structures of posttranslational modifications.