Isotope-ratio mass spectrometry (IRMS)
is a specialization of mass spectrometry
, in which mass spectrometric methods are used to measure the relative abundance of isotopes
in a given sample.
The isotope-ratio mass spectrometer (IRMS) allows the precise measurement of mixtures of stable isotopes. This technique has two different applications in the earth and environmental sciences. The analysis of 'stable isotopes
' is normally concerned with measuring isotopic variations arising from mass-dependent isotopic fractionation
in natural systems. On the other hand, radiogenic
isotope analysis involves measuring the abundances of decay-products of natural radioactivity, and is used in most long-lived radiometric dating
Most instruments used for precise determination of isotope ratios are of the magnetic sector
type. This type of analyzer is superior to the quadrupole type in this field of research for two reasons. Firstly, it can easily be set up for multiple-collector analysis, and secondly, it gives high-quality 'peak shapes'. Both of these considerations are important for isotope-ratio analysis at very high precision and accuracy.
The sector-type instrument designed by Alfred Nier
was such an advance in mass spectrometer
design that this type of instrument is often called the 'Nier type'. In the most general... Read More