Determination of gallic acid with 4-nitrobenzenediazonium tetrafluoroborate by diffuse reflectance spectrometry on polyurethane foam

AbstractThe present work describes a rapid and cost-effective analytical procedure for the determination of gallic acid. It is basedon the solid-phase extraction of gallic acid in the form of the azo compound by polyurethane foam (PUF) and measurementby diffuse reflectance spectrometry. The calibration graphs are linear over the range 0.2–6 gml −1 . The developed procedurewas applied to the determination of gallic acid in alcoholic beverages.© 2002 Elsevier Science B.V. All rights reserved. Keywords: Gallic acid; Polyurethane foam; Sorption; Diffuse reflectance spectrometry 1. IntroductionGallic acid (2,3,4-trihydroxybenzoic acid) is a natu-ral phenolic compound which is widely distributed inplants. Some pharmacological properties of this sub-stance have been described previously. For example,it has strong antimutagenic, anticarcinogenic and an-tioxidant activities [1–3]. The antioxidant activity andantiradicalar power of gallic acid have been estimatedquantitatively [1].Along with other polyphenolic compounds, gallicacid is often used as an indicator of adulteration of fruitjuices [2,4] and different alcoholic beverages [5–7].For instance, cognac and scotch whisky contain gal-lic acid, and as was shown [5], there was a good