massispektromeetria

Massispektromeetria, or mass spectrometry, is an analytical technique that measures the mass-to-charge ratio of ions to identify and quantify chemical species in a sample. In a typical workflow, the sample is ionized to generate charged particles, these ions are separated according to m/z in a mass analyzer, and the resulting ions are detected to produce a mass spectrum. The spectrum displays peaks at specific m/z values with intensities reflecting ion abundance, enabling molecular identification and, with appropriate standards, quantification.

Ionization methods vary by application. Electron ionization (EI) is common for volatile compounds, electrospray ionization (ESI) suits large and polar molecules, and matrix-assisted laser desorption/ionization (MALDI) is used for biomolecules. Other approaches include atmospheric-pressure chemical ionization (APCI) and ambient ionization techniques. Mass analyzers such as quadrupoles, time-of-flight (TOF), ion traps, Orbitraps, and FT-ICR provide different performance characteristics in resolution, accuracy, and speed. Tandem mass spectrometry (MS/MS) adds one or more fragmentation steps to obtain structural information about the ion of interest.

Applications are broad, including proteomics, metabolomics, pharmaceutical analysis, environmental monitoring, food safety, clinical diagnostics, and materials science. Quantification can be absolute or relative, often using internal standards and calibration curves; many workflows integrate separation methods like liquid chromatography (LC-MS) or imaging approaches such as MALDI imaging.

Mass spectrometry offers high sensitivity, specificity, and a wide dynamic range, along with rapid data acquisition and detailed structural insights from MS/MS. Limitations include variability in ionization efficiency, matrix effects, isobaric interferences, instrument cost, and the need for specialized data analysis and reference standards.