Analytical Potentials of Dye Extracts from Urena Lobata (Mgbo) Flowers

Author(s): Sunday O. Eze, Rose A. Ogbuefi

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Abstract: Indicators used in titrations show well-marked changes of color in certain intervals of pH. Most of these indicators are organic dyes and are of synthetic origins. The present study was designed to evaluate the extracts of a flower from a plant that is easily available. The analytical potentials of ethanol, cold water, and hot water extracts of dyes from the flowers of a common plant, Urena lobata were evaluated. 3 drops of the dye extract were dropped in 10ml of 0.1M H2SO4. This was titrated against 0.1M NaOH until the colour changed from light pink to light orange at equivalent point. The titration was repeated using standard indicators such as phenolphthalein, methyl orange, bromothymol blue and methyl red for weak acid strong base, strong acid strong base, strong acid weak base and weak acid weak of equimolar concentrations. The same acid and base of same strength were also assessed using potentiometric titration. These results indicated that flower extracts of this plant can be used as acid-base indicator in all types of  titration. The pH of these indicators was also determined. The rationale behind using these natural indicators in preference to synthetic indicators is its easy availability, inertness, ease of preparation and cost effectiveness.