Determination of salicylate, gentisic acid and salicyluric acid in human urine by capillary electrophoresis with laser-induced fluorescence detection

Sandra Zaugg, Xin Zhang, Jonathan Sweedler, Wolfgang Thormann

Research output: Contribution to journalArticlepeer-review

Abstract

Acetylsalicylic acid (Aspirin) is rapidly metabolized to salicylic acid (salicylate) and other compounds, including gentisic acid and salicyluric acid. Monitoring of salicylate and its metabolites is of toxicological, pharmacological and biomedical interest. Three capillary electrophoresis (CE) methods featuring alkaline aqueous buffers, laser-induced fluorescence (LIF) detection and no solute extraction or derivatization have been explored. A competitive binding, electrokinetic capillary-based immunoassay is developed that recognizes the presence of salicylate and gentisic acid in urine. Differentiation of the two compounds, however, is problematic. With appropriate ultraviolet excitation, many salicylate-related compounds are fluorescent so that CE with direct urine injection and LIF detection permits the determination of salicylate, gentisic acid and salicyluric acid. Using a HeCd laser with 325 nm produces interference-free monitoring of all three compounds. Using 257 nm excitation from a frequency doubled Ar ion laser, native fluorescence of an endogenous urinary compound that co-migrates with gentisic acid is observed. With wavelength-resolved fluorescence detection, however, the two substances are distinguished. Furthermore, this technique, with comparison to literature data, permits the putative assignment of several peaks to other salicylate metabolites, namely glucuronide conjugates of salicylate and salicyluric acid. All three CE-LIF techniques have been applied to toxicological patient urines and urines collected after ingestion of 500 mg acetylsalicylic acid. CE results compare favorably with those obtained by a commercial fluorescence polarization immunoassay and by a conventional photometric assay.

Original languageEnglish (US)
Pages (from-to)17-31
Number of pages15
JournalJournal of Chromatography B: Biomedical Sciences and Applications
Volume752
Issue number1
DOIs
StatePublished - Mar 5 2001

Keywords

  • Gentisic acid
  • Salicylate
  • Salicyluric acid

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Determination of salicylate, gentisic acid and salicyluric acid in human urine by capillary electrophoresis with laser-induced fluorescence detection'. Together they form a unique fingerprint.

Cite this