Massaspektroskopiaa

Massaspektroskopia, or mass spectrometry (MS), is an analytical technique that measures the mass-to-charge ratio of ions to identify and quantify molecules in a sample. It provides molecular weights, structural information, and, when combined with separation or fragmentation, detailed chemical insights. The method is widely used across chemistry, biology, and environmental sciences.

An MS instrument typically consists of an ion source, a mass analyzer, and a detector, all housed in a high-vacuum system. Ionization methods include electron impact (EI) for small, volatile compounds, and soft ionization techniques such as electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) for larger or labile molecules. The mass analyzer, such as a quadrupole, time-of-flight (TOF), ion trap, Orbitrap, or FT-ICR, separates ions by m/z before detection.

Tandem MS (MS/MS) enables structural information by fragmenting selected ions, typically by collision-induced dissociation. Accurate mass measurements and isotope patterns support formula assignments, while database searching and spectral libraries facilitate identification. Quantification can be absolute or relative, often using internal standards and calibration curves.

Mass spectrometry has broad applications in proteomics, metabolomics, pharmacokinetics, environmental analysis, and materials science. Limitations include ionization bias, matrix effects, and the need for specialized interpretation software. Complex mixtures may require chromatographic separation (LC-MS) to resolve overlapping species. Instrument choice depends on the target analytes, required resolution, and sensitivity.