Original Articles: 2011 Vol: 3 Issue: 2
Isolation of herbal acid-base indicator from the seeds of Punica granatum
Abstract
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 methanolic
fruit extract of Punica granatum and to replace the synthetic indicators as they have certain
disadvantages like chemical pollution, availability problems and high cost. Methanolic fruit
extract of Punica granatum from family Puniceaceae gives sharp and intense color changes as
compared to Phenolphthalein, Methyl Red and Phenol Red. Herbal indicators are evaluated by
using strong acid-strong base, strong acid-weak base, weak acid-strong base and weak acidweak
base. In all these titrations the extract was found to be very useful and accurate for
indicating the neutralization point