Michael Vogeser1, Gustav Schelling. 1. Institute of Clinical Chemistry, Hospital of the University of Munich, Munich, Germany. michael.vogeser@med.uni-muenchen.de
Abstract
BACKGROUND: The endocannabinoid 2-arachidonoyl glycerol (2-AG) undergoes spontaneous isomerization to biologically inactive 1-AG. This effect has not been adequately addressed in previous studies that reported 2-AG concentrations in biological samples. METHODS: Liquid chromatography tandem-mass spectrometry (LC-MS/MS) was used for 1-AG and 2-AG analyses. RESULTS: Identical collision-induced disintegration spectra were found for 1-AG and 2-AG. For specific detection of both compounds, which share a common mass transition, baseline chromatographic separation is mandatory, even when applying MS/MS technology with its generally high detection specificity. When using standard chromatographic conditions with the very short run times typically used in LC-MS/MS methods, co-elution of 2-AG with 1-AG, which is present in human serum, causes false 2-AG results. CONCLUSIONS: Our data highlight that the analytical specificity of MS/MS can be limited by interference from isobaric isomers with identical disintegration patterns. The specificity of this technology must be carefully evaluated for each individual application.
BACKGROUND: The endocannabinoid2-arachidonoyl glycerol (2-AG) undergoes spontaneous isomerization to biologically inactive 1-AG. This effect has not been adequately addressed in previous studies that reported 2-AG concentrations in biological samples. METHODS: Liquid chromatography tandem-mass spectrometry (LC-MS/MS) was used for 1-AG and 2-AG analyses. RESULTS: Identical collision-induced disintegration spectra were found for 1-AG and 2-AG. For specific detection of both compounds, which share a common mass transition, baseline chromatographic separation is mandatory, even when applying MS/MS technology with its generally high detection specificity. When using standard chromatographic conditions with the very short run times typically used in LC-MS/MS methods, co-elution of 2-AG with 1-AG, which is present in human serum, causes false 2-AG results. CONCLUSIONS: Our data highlight that the analytical specificity of MS/MS can be limited by interference from isobaric isomers with identical disintegration patterns. The specificity of this technology must be carefully evaluated for each individual application.
Authors: M Feuerecker; D Hauer; R Toth; F Demetz; J Hölzl; M Thiel; I Kaufmann; G Schelling; A Choukèr Journal: Eur J Appl Physiol Date: 2011-11-19 Impact factor: 3.078
Authors: Piray Atsak; Daniela Hauer; Patrizia Campolongo; Gustav Schelling; James L McGaugh; Benno Roozendaal Journal: Proc Natl Acad Sci U S A Date: 2012-02-13 Impact factor: 11.205
Authors: Hannah L Pellkofer; Joachim Havla; Daniela Hauer; Gustav Schelling; Shahnaz C Azad; Tania Kuempfel; Walter Magerl; Volker Huge Journal: PLoS One Date: 2013-08-09 Impact factor: 3.240