Determination of total and non-protein-bound fractions of L-Dopa in blood plasma by liquid chromatography and electro-chemistry

V. Rizzo, R. Pastore, S. Pankopf, G. V. Melzi D'Eril, R. Moratti

Research output: Contribution to journalArticlepeer-review

Abstract

We devised a procedure for the determination of the total and the non-protein-bound fraction of 3,4-dihydroxyphenylalanine (L-Dopa) in plasma. The optimization of the plasma sample purification for the determination of the total L-Dopa involves precipitation of the proteins with trichloroacetic acid. Determination of the non-protein-bound fraction involves ultrafiltration through a membrane with a molecular mass cut-off of 10 kDa Before ultrafiltration, a small amount (5 μl) of 4 M orthophosphoric acid was added in the bottom of the cone. This stabilizes the L-Dopa separated from plasma. After purification of the sample, L-Dopa was determined by a reversed-phase liquid chromatography system coupled with a three-electrode coulometric detection Sample run time was less than 5 min. With this method, the detector response was linear from endogenous levels of L-Dopa up to therapeutic concentration The method represents a valid tool for the rapid and accurate measurement of total and non-protein-bound L-Dopa in plasma samples for therapeutic monitoring of Parkinson patients treated with L-Dopa.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalBiogenic Amines
Volume12
Issue number1
Publication statusPublished - 1996

Keywords

  • Non-protein-bound L-Dopa
  • Parkinson's disease
  • Total L-Dopa
  • Ultrafiltration

ASJC Scopus subject areas

  • Neuroscience(all)
  • Pharmacology

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