Mass spectrometry is a powerful analytical technique used to determine the mass and structure of molecules by converting them into ions and measuring their mass to charge ratios. It has become a central tool in chemistry, biology, environmental science, and medicine due to its high sensitivity, specificity, and speed.

The basic workflow begins with ionization of the sample, separation of ions in a mass analyzer, and detection of their signals to generate a mass spectrum. Different ionization methods are tailored to different types of samples. Electron ionization is commonly used for small, volatile molecules, while electrospray ionization and matrix assisted laser desorption ionization are suited to large, fragile biomolecules such as proteins and peptides.

Mass analyzers including quadrupoles, time of flight instruments, ion traps, and Orbitraps differ in resolution, speed, and mass accuracy. Hybrid instruments, such as quadrupole time of flight and tandem mass spectrometers, enable multiple stages of mass analysis, allowing detailed structural characterization through fragmentation patterns.

Applications span from proteomics, where thousands of proteins and their modifications can be identified in complex mixtures, to metabolomics, lipidomics, and small molecule analysis. In clinical contexts, mass spectrometry supports biomarker discovery, drug monitoring, and diagnostics. In environmental and space sciences, it is used to track pollutants and analyze planetary atmospheres and extraterrestrial materials.

Ongoing research focuses on improving sensitivity, resolution, and quantification, miniaturizing instruments for field and point of care use, integrating separation techniques such as liquid chromatography, and developing advanced data analysis methods, including machine learning, to interpret increasingly complex spectra.