Preparation and use of <i>Acanthus sennii chiovenda</i> flower extract as a green substitute for synthetic acid-base indicators

Abstract

Due to environmental friendliness, availability and cost, the search for natural compounds as acid-base indicators has continued. Certain highly coloured pigments obtained from plants produce changes in colour with varying pH. This study has been conducted to investigate the indicator property of ethanolic and acidified ethanol extracts of Acanthus sennii chiovenda flower and compare the results with that of already existing synthetic indicators (phenolphthalein, bromothymol blue and methyl red). Flower extracts of the plant were characterized with ultraviolet-visible spectrophotometer and phytochemical screening test. The colour change with respect to varying pH was also examined by adding four drops of flower extracts of this plant to definite volume of solutions at various pH. The flower extracts of the plant were applied in titrimetric analysis for four types of acid-base titrations. Phytochemical analysis and spectral studies confirmed presence of anthocyanins and flavonoids in ethanol and acidified ethanol Acanthus sennii chiovenda flower extracts responsible for accurate and sharp color change at the end point. The results indicated that flower extracts of this plant can be used as acid-base indicators. Statistical tests and comparisons are made with performances of the synthetic indicators.