massaspectra

Mass aspectra are the outputs produced by mass spectrometry, displaying the relative abundance of ions as a function of their mass-to-charge ratio (m/z). They are central to identifying and characterizing chemical species in a wide range of disciplines, from chemistry to biology.

Mass aspectra are generated by ionizing sample molecules and separating the resulting ions by m/z. Common ionization methods include electron ionization (EI), which often produces extensive fragmentation, electrospray ionization (ESI), which yields multiply charged ions, and matrix-assisted laser desorption/ionization (MALDI), well suited for large biomolecules. The ions are analyzed by mass analyzers such as quadrupoles, time-of-flight (TOF), ion traps, Orbitraps, or Fourier transform ion cyclotron resonance (FT-ICR). Detection translates ion signals into a spectrum. High-resolution and accurate-mass instruments provide precise m/z values, enabling determination of elemental compositions.

Key features of mass aspectra include the molecular ion peak (the intact molecule), fragmentation peaks that reveal structural information, and isotopic patterns that reflect the elemental composition (for example, Cl or Br isotopes). The base peak is the most intense signal and often guides interpretation. Tandem mass spectrometry (MS/MS) further fragments selected precursor ions to elucidate substructures.

Applications are broad: identification and purity assessment of small molecules, proteomics and metabolomics, pharmaceutical analysis, environmental testing, and forensic science. Data interpretation often relies on spectral libraries (such as NIST) and software for peak assignment, isotope pattern matching, and formula determination. Mass aspectra thus provide a foundational, versatile tool for chemical analysis and structural elucidation.