Mass spectrum
A mass spectrum is an intensity versus m/z (mass-to-charge ratio) plot that represents a chemical analysis.[2] The mass spectrum of a sample is a pattern representing the distribution of ions by mass (more correctly: mass-to-charge ratio) in a sample. It is a histogram usually made using an instrument called a mass spectrometer. Not all mass spectra of a given substance are the same. It can depend on the operating conditions of the instrument. For example, some mass spectrometers break the analyte molecules into many pieces; others observe the intact molecular masses with little fragmentation. A mass spectrum can represent many different types of information based on the type of mass spectrometer and the specific experiment; however, all plots of intensity vs. mass-to-charge are called "mass spectra".
Common fragmentation processes for organic molecules are the McLafferty rearrangement and alpha cleavage.
In the past, chemists with PhD degrees were needed to interpret mass spectra. Today, computer programs read the data and identify the compounds in a sample.
Mass Spectrum Media
Mass spectrum of sodium and potassium positive ions from Arthur Dempster's 1918 publication "A new Method of Positive Ray Analysis " Phys. Rev. 11, 316 (1918)
References
Other websites
- Interactive tutorial on mass spectra Archived 2014-10-23 at the Wayback Machine National High Magnetic Field Laboratory
- Weighing Atoms: A layperson's introduction to mass spectrometry Archived 2011-09-27 at the Wayback Machine National High Magnetic Field Laboratory
- What's in an Oil Drop: A layperson's introduction to Fourier Transform Ion Cyclotron Resonance Archived 2011-09-27 at the Wayback Machine National High Magnetic Field Laboratory
- Quantities, Units and Symbols in Physical Chemistry (IUPAC green book)
- An introductory video on Mass Spectrometry The Royal Society of Chemistry