massaspectrometer

A mass spectrometer is an analytical instrument that measures the masses of ions to determine the composition and structure of molecules. It converts a sample into charged particles, selects ions by their mass-to-charge ratio (m/z), and records a signal proportional to ion abundance.

The typical workflow involves ionization, mass analysis, and detection, with data processing to produce a spectrum. Ionization methods vary: electron impact for small molecules; electrospray for large biomolecules; and matrix-assisted laser desorption/ionization for polymers and proteins. The instrument operates under high vacuum to minimize collisions.

Mass analyzers include magnetic sector, quadrupole, time-of-flight, ion trap, Orbitrap, and Fourier transform ion cyclotron resonance. Each offers trade-offs among mass range, resolution, and scanning speed; for example, TOF and magnetic sector provide broad ranges, while Orbitrap and FT-ICR give high resolution and accuracy.

Applications span chemistry, proteomics, metabolomics, environmental analysis, pharmaceuticals, and materials science. High-resolution mass spectrometry enables exact mass determination, isotope pattern analysis, and complex mixture profiling. When paired with chromatography (LC-MS, GC-MS), it separates components before analysis.

Origins trace to J. J. Thomson and the Aston mass spectrograph in the early 20th century. Modern developments in electrospray and MALDI in the 1980s–1990s expanded use to large biomolecules and complex samples.

Limitations include ionization bias, matrix effects, and the need for high vacuum and careful calibration. Sensitivity and dynamic range vary by instrument design.

Performance is described by mass range, resolution, mass accuracy, and sensitivity. State-of-the-art systems achieve sub-ppm mass accuracy and high resolving power.