Mass spectrometry is an analytical technique that measures the mass to charge ratio of ions to identify and quantify atoms and molecules. It is built around three core steps: ionization of the sample, separation of ions based on their mass to charge ratio, and detection of those ions. Different ionization methods, such as electron ionization and electrospray ionization, allow analysis of gases, liquids, and large biomolecules with minimal fragmentation when needed.

A mass spectrometer typically consists of an ion source, a mass analyzer, and a detector. Common mass analyzers include quadrupoles, time of flight systems, ion traps, orbitraps, and Fourier transform ion cyclotron resonance instruments. These differ in resolution, mass accuracy, speed, and cost, which determines their suitability for tasks ranging from routine quantification to high precision structural studies.

Mass spectrometry is widely used in chemistry, biology, environmental science, and medicine. In proteomics it enables identification of thousands of proteins in complex samples, detection of post translational modifications, and mapping of protein interactions. In metabolomics and lipidomics it provides detailed chemical profiles that help reveal disease mechanisms or responses to treatment.

The technique also supports pharmaceutical development through impurity analysis, stability studies, and pharmacokinetic measurements. In clinical settings it offers highly specific assays for biomarkers and drugs in blood and other body fluids. Improvements in resolution, sensitivity, and data analysis algorithms are expanding applications toward single cell measurements, real time monitoring, and integration with other methods such as chromatography and imaging, making mass spectrometry a central tool in modern analytical science.