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CHAPTER 6

Instrumental Isotopic Fractionation

In mass spectrometry, the term ‘instrumental isotopic fractionation’ is recommended to describe the sum of the effects in a mass spectrometer occurring during sample introduction, ion formation, ion extraction, ion separation and ion detection leading to a difference of the measured isotope ratio from the true isotope ratio in a sample. Instrumental isotopic fractionation (IIF) describes the instrumental fractionation between nuclides of the same element resulting in erroneous results of isotope ratios. The major aspects of IIF for the different techniques (i.e. (LA)-ICP-MS, GDMS, TIMS, SIMS and IRMS) based on magnetic sector field analysers are presented. A special focus is set on the description of the major causes of IIF, the areas of occurrence in the respective instrumentations as well as the impact of IIF on the final measurement result and the related measurement uncertainty. The described techniques differ strongly in the extent of IIF, mainly due to the different ionization sources as well as vacuum conditions.

Print publication date: 26 Nov 2014
Copyright year: 2015
Print ISBN: 978-1-84973-392-2
PDF eISBN: 978-1-84973-540-7
ePub eISBN: 978-1-78262-356-4
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