Determination of lipoic acid and dihydrolipoic acid in human plasma and urine by high-performance liquid chromatography with fluorimetric detection

Abdullah I. Haj-Yehia*, Peter Assaf, Taher Nassar, Jehoshua Katzhendler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

A highly sensitive method for the determination of α-lipoic acid (LA) and dihydrolipoic acid (DHLA) in human plasma and urine has been developed. Samples were acidified and extracted with organic solvent, and the free sulfhydryls of DHLA protected as the dicarboxyethylate by treatment with ethylchloroformate. The free carboxylic function of LA and the SH-protected DHLA were converted into their amide derivatives with the strong fluorophore 2-(4-aminophenyl)-6-methylbenzothiazole in the presence of a coupling agent and a base catalyst. The resulting fluorescent amides of both LA and DHLA were separated on a reversed-phase column (Ultrasphere C8) using simple isocratic elution with acetonitrile-water (80:20) and detected fluorimetrically (excitation 343, emission 423 nm). The method is highly sensitive, reproducible, and is easily applied for the simultaneous determination of LA and DHLA in biological samples. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)381-388
Number of pages8
JournalJournal of Chromatography A
Volume870
Issue number1-2
DOIs
StatePublished - 18 Feb 2000

Keywords

  • Aminophenylmethylbenzothiazole
  • Derivatization, LC
  • Dihydrolipoic acid
  • Lipoic acid
  • Thiols

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