It was demonstrated that substituted indoles fully labelled with deuterium on the aromatic ring can undergo substantial exchange back to partial and even fully protonated forms during Atmospheric Pressure Chemical Ionisation (APCI) LC-MS. The degree of this exchange was strongly dependent on the absolute quantity of analyte, the APCI desolvation temperature, the nature of the mobile phase, the mobile phase flow rate and the instrument used. H-D exchange on several other aromatic ring systems during APCI LC-MS was either undetectable (nitrobenzene, aniline) or extremely small (acetanilide) compared to the effect observed for substituted indoles. This observation has major implications for quantitative assays using deuterium labelled internal standards and for the detection of deuterium labelled products from isotopically labelled feeding experiments where there is a risk of back exchange to the protonated form during the analysis.
History
Publication title
Rapid Communications in Mass Spectrometry
Volume
24
Issue
7
Pagination
1105-1110
ISSN
1097-0231
Department/School
School of Natural Sciences
Publisher
John Wiley & Sons
Place of publication
New York
Rights statement
The definitive published version is available online at: http://interscience.wiley.com