Evaluation of different cyclodextrins media for the determination of Serotonin and 5-hydroxyindole acetic acid in urine

A. G. BRACAMONTE; A. V. VEGLIA*

ANALYTICAL BIOCHEMISTRY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Shanon (Ireland); Año: 2009 vol. ENV

0003-2697

Trabajo enviado a consideración 20.11.09 Abstract Alternative and sensitive spectrofluorimetric methods for the determination of hydroxyindoles, such as serotonin (5HT) and 5-hydroxyindoleacetic acid (5HIA), were developed on the basis of supramolecular interaction with cyclodextrin (CD) nanocavities (ßCD and hydroxypropylßCD, HPCD) at different pH values. Both substrates and receptors have acidic protons, therefore the interactions produced in different systems were considered. The effects of neutral CD at pH = 2.00 and 6.994 and the anionic CD at pH =13.00 on the specific acid-base species of the compounds at each pH were determined. In all the conditions studied, the fluorescence of the substrates in the presence of CD showed an increase. The association constants (KA, M-1) between the substrates and CD were determined (30 -300) and interpreted. The limits of detection (LD, ng mL-1) for the best conditions were 0.37 for 5HT and 0.50 for 5HIA at pH = 2.00 with HPCD. These LD were better than other reported. A zero-crossing first derivative spectrofluorimetric method with and without HPCD was developed for the simultaneous determination of 5HT and 5HIA. The applicability of the direct and derivative spectrofluorimetric methods in urine samples was demonstrated with good recoveries 92-110 % and R.S.D. 1-10 %.