High speed liquid chromatography of phenylethanolamines for the kinetic analysis of [11C]-meta-hydroxyephedrine and metabolites in plasma

Jeanne M. Link, Robert E. Synovec, Kenneth A. Krohn, James H. Caldwell

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

A method is developed and described for analysis of [11C]-meta-hydroxyephedrine, [11C]MHED, a tracer of cardiac function, and its metabolites in plasma samples. The method combines on-column solid-phase extraction and separation on a single weak cation-exchange column. Phenylethanolamines were used to develop the separation method that concentrates the analytes on-column from physiological saline and then elutes them by changing to an acidic mobile phase. Hydrophobic interactions determine the selectivity, and elution order is the same as for reversed-phase liquid chromatography on a C,, stationary phase. The mechanism of separation is mixed mode, with ion-exchange coupled with a reversed-phase liquid chromatography mechanism. Each sample analysis requires only 10 min and does not require deproteinization or the use of organic solvents. In human samples, a single plasma metabolite of [11C]MHED along with the parent compound were observed using this method. The method was sufficiently rapid so that in 70 min seven samples were assayed, providing a well-defined time course for MHED and its metabolites in blood. The metabolite concentration increased with time to ~85% of the plasma activity 50 min after administration. The results with the developed method are comparable to those described for reversed-phase separations, with the advantage that our method does not require deproteinization, reducing sample analysis time by a factor of two.

Original languageEnglish (US)
Pages (from-to)31-41
Number of pages11
JournalJournal of Chromatography B: Biomedical Applications
Volume693
Issue number1
DOIs
StatePublished - May 23 1997

Keywords

  • Hydroxyephedrine
  • Phenylethanolamines

ASJC Scopus subject areas

  • Chemistry(all)

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