Determination of amino acids in urine by cyclodextrin-modified capillary electrophoresis-laser-induced fluorescence detection

Takashi Kaneta, Hiromasa Maeda, Mari Miyazaki, Rina Miyake, Hirotomo Izaki, Yuji Sakoda, Shohei Kinoshita, Totaro Imasaka

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Capillary electrophoresis (CE) combined with laser-induced fluorescence detection is applied to the determination of amino acids in urine samples. The urine samples are first ultrafiltered, to remove proteins and large peptides, and the filtrates are then directly labeled by reaction with fluorescein isothiocyanate (FITC). Cyclodextrin-modified CE using α-cyclodextrin is employed for the separation of the FITC-labeled amino acids. Seven amino acids are clearly separated from side reaction products produced during the labeling reaction, when an 80mM borate buffer containing 45mM α-cyclodextrin is used as the running buffer. For quantitative analysis, rhodamine B is added to the labeled urine samples as an internal standard. The calibration curves for phenylalanine, glutamine, proline, glycine, serine, alanine, and valine are linear in the range of 10μM to 100μM. The concentration limits of detection for all of the amino acids are estimated to be 160-330nM. Conversely, the limit of quantitation (LOQ) was ∼10μM and the limitations are due to the labeling efficiency rather than the sensitivity of the detector. Three amino acids in urine samples, glutamine, glycine, and alanine, are readily quantitated, while the concentrations of the others are below the LOQ. The present method would permit the determination of seven amino acids in urine successfully.

Original languageEnglish
Pages (from-to)712-716
Number of pages5
JournalJournal of Chromatographic Science
Volume46
Issue number8
DOIs
Publication statusPublished - Sep 2008
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry

Fingerprint Dive into the research topics of 'Determination of amino acids in urine by cyclodextrin-modified capillary electrophoresis-laser-induced fluorescence detection'. Together they form a unique fingerprint.

  • Cite this