In acid- base titrations, indicators are used to show a sharp color changes at interval of pH. Natural pigments in plants are highly colored substances and may show color changes with variation of pH. An attempt has been made to investigate the indicator activity of Ipomoea coccinea and Bauhinia Purpurea L ethanolic extract and to replace the synthetic indicators as they have certain disadvantages like chemical hazard. Herbal indicators are evaluated by using strong acid-strong base, strong acid-weak base, weak acid-strong base and weak acid weak base. In all these titrations the extract was found to be very useful and accurate for indicating the neutralization point. Assay of aspirin and citric acid was carried out using flower extract as an indicator. %RSD was found 0.1 and 0.2 respectively for citric acid and aspirin. These indicate that this flower extract can successfully replace phenol red and phenolphthalein.
Loading....