Utilization of folin-ciocalteu phenol reagent for the detection

J. Agric. Food Chem. 2003, 51, 1811−1815

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Utilization of Folin−Ciocalteu Phenol Reagent for the Detection of Certain Nitrogen Compounds
MIYOSHI IKAWA,* TIMOTHY D. SCHAPER, CATHERINE A. DOLLARD,
JOHN J. SASNER

AND

Department of Zoology and Center for Freshwater Biology, University of New Hampshire,
Durham, New Hampshire 03824

To determine in more detail the reaction of Folin-Ciocalteu phenol reagent with nitrogen compounds, a number of hydroxylamine-related compounds and a large number of guanidine-containing compounds were tested. In general, guanidine compounds did not react strongly unless they were hydroxyamino or hydrazino derivatives. The non-hydroxyamino paralytic shellfish poison saxitoxin, however, reacted to a significant extent. This may be due to the presence of a five-membered ring structure and its analogy to 2-aminopurines, which react strongly. A number of simpler amines were also tested. Tertiary aliphatic amines, but not primary, secondary, or quaternary amines, reacted strongly with the reagent. Primary, secondary, and tertiary aromatic amines all reacted strongly with the reagent. Reactivity was extended to pyrroles and indole derivatives but not to imidazole and benzimidazole derivatives. Defining the reactivity of Folin-Ciocalteau phenol reagent with nitrogen compounds extends the usefulness of the reagent for the detection and determination of certain nitrogen compounds in basic extracts by colorimetric means and by thin-layer chromatography.
KEYWORDS: Folin-Ciocalteu reagent; guanidines; paralytic shellfish poisons; hydroxylamine derivatives; amines INTRODUCTION

Folin-Ciocalteu phenol reagent consists of a mixture of the heteropoly acids, phosphomolybdic and phoshotungstic acids, in which the molybdenum and tungsten are in the 6+ state. On reduction with certain reducing agents, the so-called molybdenum blue and tungsten blue are formed, in which the mean oxidation state of the metals is between 5