Isotopic labelling in mass spectrometry as a tool for studying reaction mechanisms of ion dissociations

Abstract

Perhaps the greatest influence that isotopic labelling experiments have had on organic mass spectrometry is that reaction mechanisms originally borrowed from the chemistry of neutral counterparts have proved to be inadequate for explaining the results. It was therefore necessary to devise completely new types of fragmentation mechanisms and unconventional structures for organic gas-phase cations. In most cases the labelling technique allows one to discover the positions at which the label atoms are found in both the charged and neutral products of an ion's dissociation. These experimental results are often difficult to rationalize by any simple mechanism, but they nearly always indicate how chemical computations should be directed in order for the latter to be able to provide a better mechanistic understanding. This short article describes some significant studies involving D and 18-O labelling that well support the above assertions, using as examples the behaviour of some quite simple organic molecules.

Deuterium‐ and Tritium‐Labelled Compounds: Applications in the Life Sciences

“…Aside from their use in relation to the kinetic isotope effect, stable isotopes are also utilized as tracers for mechanistic investigations to determine the nature of intermediates in chemical reactions or to support the elucidation of biosynthetic pathways . The focus in such studies is primarily on the location and distribution of the label to follow atoms through the synthetic assembly, for example, by label‐facilitated MS or NMR analysis …”

“…[36] Thefocus in such studies is primarily on the location and distribution of the label to follow atoms through the synthetic assembly,for example,b yl abelfacilitated MS or NMR analysis. [29,37]…”

Deuterium‐ und tritiummarkierte Verbindungen: Anwendungen in den modernen Biowissenschaften

“…[36] Der Fokus solcher Studien liegt hauptsächlich auf der Lokalisierung und Verteilung des Tr acers,u mz .B.d urch tracerbasierte MS-oder NMR-Analyse den Verbleib von Atomen in einer Synthese zu verfolgen. [29,37] …”

Isotope effects: recent developments in chemistry and biochemistry

“…19,20 It is my sincere hope, and that of the editors of JLCR, that readers will find these articles enjoyable to read as well as useful in their professional careers. In this aspect, I must add that in the planning of this issue, to which my colleague and JLCR Editor-in-Chief, John Jones, contributed greatly, the topics and reviewers chosen for this Special Issue were intended to be different from regular contributions to the journal, reporting by and large original studies relating to drug discovery research, and also to serve in a complementary manner by keeping abreast of fundamental developments.…”