A form of mass spectrometry that is used for rapid qualitative and quantitative characterization of samples of biomolecules in a wide range of applications. The test sample is applied to a specially designed matrix on a target plate, which is then irradiated with ultraviolet light from a laser. This heats the matrix, the surface of which vaporizes along with the sample, which is ionized in the process. These ions are directed by electric fields along a flight tube towards a detector. The time of flight depends on the mass-to-charge ratio of each ion—smaller or more highly charged ions move faster. The outcome is a spectrum of the ionized fragments of the test sample. This is compared with a range of standard samples, and the nature of the test sample is established. The technique is a rapid and relatively simple way of identifying bacterial or yeast cells according to their spectra, which are compared with a database of clinically relevant standard spectra. The rapid identification of proteins and peptides is another application.