Spectrofluorimetric determination of 5-hydroxyindoles with benzylamine or 3,4-dimethoxybenzylamine as a selective fluorogenic reagent

ANALYSTANALYST Pub Date: DOI: 10.1039/AN9911600301

Abstract

A spectrofluorimetric method has been developed for the sensitive and selective determination of 5-hydroxyindoles; the method is based on the reaction of 5-hydroxyindoles in a weakly alkaline solution (pH 9.0) with aromatic methylamines in the presence of potassium hexacyanoferrate(III) and dimethyl sulphoxide; the compounds produced fluoresce intensely in an alkaline solution (pH 11–12). Of the eight aromatic methylamines tested, benzylamine and 3,4-dimethoxybenzylamine were found to be the most favourable fluorogenic reagents in terms of sensitivity and reactivity. The methods with benzylamine and 3,4-dimethoxybenzylamine permit the determination of 5-hydroxyindoles at concentrations as low as 22–72 pmol ml–1 and 1.0–2.4 nmol ml–1, respectively.

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