Massaspektrometriaan

Massaspektrometriaan is an analytical technique used to determine the mass-to-charge ratio of ions, enabling identification and quantification of molecules in complex mixtures, as well as insights into molecular structure and composition. It is widely applied in chemistry, biology, environmental science, and medicine. The method relies on converting samples into charged particles, separating these ions by their m/z in vacuum, and detecting them to produce a mass spectrum.

Principles of operation involve ionization of the sample to form charged species, followed by mass analysis and detection. The mass spectrum shows signal intensity as a function of m/z, with peaks corresponding to ion species. High-resolution and accurate mass measurements help determine molecular formulas and distinguish closely related compounds. Fragmentation of ions during analysis (tandem MS) provides structural information and support for identification.

A typical mass spectrometry setup includes an ion source, a mass analyzer, a detector, and a data system. Ionization methods vary with sample type: electron ionization is common for small, volatile molecules; electrospray ionization is well suited for large biomolecules; matrix-assisted laser desorption/ionization is effective for proteins and polymers. Mass spectrometers are often combined with chromatographic separation such as LC-MS or GC-MS to handle complex samples.

Common mass analyzers include quadrupole, time-of-flight, ion trap, orbitrap, and Fourier-transform ion cyclotron resonance (FT-ICR). These differ in mass resolution, sensitivity, and speed. Tandem mass spectrometry (MS/MS) uses successive stages of mass selection and fragmentation, increasing specificity and enabling detailed structural studies.

Applications span proteomics, metabolomics, pharmaceutical analysis, environmental monitoring, food safety, forensics, and clinical diagnostics. The field has evolved from early studies in the 1910s and 1920s to modern high-resolution and tandem instruments that provide precise molecular information at trace levels.