Capillary electrophoretic and micellar electrokinetic separations of asymmetric dimethyl-L-arginine and structurally related amino acids: Quantitation in human plasma

Gabriele Trapp, Karsten Sydow, Maria T. Dulay, Tina Chou, John P. Cooke, Richard N. Zare

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

We report the development of efficient electrophoretic methods for the separation and quantification of L-arginine and six naturally occurring derivatives that are structurally and functionally related. Capillary electrophoresis (CE) employing a concentrated borate buffer at pH 9.4 achieves the separation of mixtures containing dimethyl-L-arginine, NG-monomethyl-L-arginine, L-arginine, L-homoarginine, L-ornithine, and L-citrulline as 4-fluoro-7-nitrobenzofurazan derivatives. In addition, the separation of the isomeric dimethyl-L-arginine derivatives (symmetric and asymmetric) is attained with baseline resolution by micellar electrokinetic chromatography (MEKC) when a high concentration of deoxycholic acid is added as a surfactant to the same running buffer. The influence of buffer type, concentration, and pH on the separation was studied to optimize separation conditions. The limit of quantitation (LOQ) for asymmetric dimethyl-L-arginine in aqueous solution was determined to be 20 μM using UV absorption in a CE separation and 0.1 μM using laser induced fluorescence (LIF) detection in an MEKC separation. This newly developed method was successfully applied for the quantitation of asymmetric dimethyl-L-arginine and L-arginine in human plasma samples at levels that might be used as a clinical diagnostic for cardiovascular disease (0.125 μM LOQ).

Original languageEnglish (US)
Pages (from-to)1483-1490
Number of pages8
JournalJournal of Separation Science
Volume27
Issue number17-18
DOIs
StatePublished - Dec 2004

Keywords

  • Amino acids
  • Capillary electrophoresis
  • Dimethyl-L-arginine
  • Micellar electrokinetic chromatography

ASJC Scopus subject areas

  • Molecular Medicine
  • Clinical Biochemistry
  • Chemical Engineering(all)
  • Filtration and Separation

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