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Consequences of the formation of 3,4-dimethyl-5-phenyl-1,3-oxazolidine on the analysis of ephedrines in urine by gas chromatography and a new method for confirmation as N-trifluoroacetyl-O-t-butyldimethylsilyl ether derivatives

Authors
Journal
Journal of Chromatography A
0021-9673
Publisher
Elsevier
Publication Date
Volume
1218
Issue
9
Identifiers
DOI: 10.1016/j.chroma.2010.12.120
Keywords
  • Pseudoephedrine
  • Ephedrine
  • Artifact
  • Gas Chromatography
  • Mtbstfa
  • Doping
Disciplines
  • Criminology
  • Medicine

Abstract

Abstract The compound 3,4-dimethyl-5-phenyl-1,3-oxazolidine can appear as an artifact during the gas chromatographic analysis of ephedrines. Its presence is a risk for doping control and forensic analyses. An evaluation about the consequences of its formation showed the possibility of a false positive for ephedrine, a false negative for pseudophedrine and increased uncertainty in the quantitative approach. Misinterpretations can be avoided with the observation of fragments m/ z 56 and 71 in the ephedrine mass spectrum during GC–MS analysis and also by the formation of N-TFA-O-TBDMS derivatives prior to GC analysis. These N-TFA-O-TBDMS derivatives lead to an increase in the number and mass of diagnostic ions, meet the identification criteria, and provide an improvement in chromatographic resolution, allowing the separation of the ephedrines.

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