Separation and o-phthaldehyde fluorometric determination of 5-hydroxy- and 5-methoxyindoleamines by thin-layer...

Individual 5-hydroxyindoles and 5-methoxyindoles were simultaneously isolated and quantified, after o-phthaldehyde condensation in different concentrations of HCl, followed by separation on silica gel plates. The 5-hydroxyindoleamines and 5-methoxyindoleamines were differentiated by intense orange and blue fluorescences, respectively. Distinct Rf values with new phase composition and optimal HCl concentrations in the condensation reaction were established for each of the nine indoleamines tested. Minimal detectable doses ranged from 0.2 ng for 5-methoxytryptophol to 4 ng for 5-hydroxyindole acetic acid. The above methodology was applied in order to determine platelet serotonin. Preliminary results suggest that this method could be adapted to other selected biological samples.