SPECTROPHOTOMATRIC & POTENTIOMETRIC STUDY OF AQUEOUS & ETHANOLIC EXTRACTS OF HIBISCUS SABDARIFFA L. FLOWERS (KUJARAT TEA)

Abstract

The spectrophotomatric spectra in UV, Visible and IR regions have revealed thepresence of many functional groups in the aqueous and ethanolic extracts of Hibiscus sabdariffa L.flowers .Paper, thin-layer and column chromatographic techniques have shown the presence of threepigments in both extracts ; Gossypetin, Anthocynin, and Querectin .Five organic acids were alsoseparated and identified in both extracts .All these compounds were identified by UV, Visible and IRspectrophotomatry of electromagnetic radiation .Flame atomic absorption and emission techniquehaveoffered high levels of determination of calcium, barium, potassium and magnesium, while sodium,lithium, iron, manganese, copper, zinc and nickel were found in traces .pH and potential titrations ofthe extracts with standardized NaOH have shown high inflections at equivalence points which wereexploited in the determination of total acids in the extract which was more than 28% .The suddencolour change from violet, red or pinkish of the extract into green has led us to exploit the extracts asan acid-base indicator . The data and results obtained have clarified that the extracts of Hibiscussabdariffa L. flowers are matching the action of other indicators used in acid-base titrations