An Investigation of the Analytical Potentials of Flower Extracts as Bio-Indicators in Acid Base Titration
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Date
2018
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School of Science and Engineering, Southeast University, Dhaka, Bangladesh
Abstract
This study investigates the potentials of flower extracts namely, Hibiscus Rosa-sinensis (red hibiscus flower), Plumeria Alba (White Frangipani flower), Bombax Buonopozense (Red flower silk cotton flower) Tabebuia Rosea (Pink trumpet flower) and Tecoma Stans (Yellow bells flower) as bio-indicators and substitutes for commonly used synthetic indicators such as methyl orange and phenolphthalein. The bio-indicators were prepared through sun-drying, pulverisation and solubilisation of the flower petals in solvents (acetone, ethanol, water, acetone/ethanol mixture and ethanol/water mixture) of various solvatrochromic parameters followed by strong agitation at room temperature.Titration of strong acid against strong base was carried out using the prepared five different indicators and the synthetic indicators (methyl orange and phenolphthalein) to serve as control. Plumeria Alba (White Frangipani flower) petals dissolved in ethanol was found to be a highly promising bio- indicator with a competing average titre value of 29.50 cm3 against methyl orange with average titre value of 29.30 cm3.The Fourier transform infra red study shows that the presence of the C=C stretch and vibration band at 1605 cm-1 found in the synthetic indicators used was also present in PLA flower extract. A regression model in terms of solvent polarity, Hasen dispersion bond solubility parameter and and bio-indicator pH was developed for the prediction of average titre values.The model was found to give excellent prediction only for bio-indicators obtained from solvent of low (<25) polarity index.
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Keywords
Flower extracts, Bio-Indicators, Regression model, Hasen solubility parameter, Solvatrochromic parameters