Extraction of an acid base indicator from passiflora edulis peels.

Abstract

In routine experiments synthetic indicators are the choice of acid base titrations. But there are some limitations like environmental pollution, availability and higher cost which lead to utilisation for natural compounds as acid base indicators. Natural indicators are easy to prepare, easily available and have no toxic effects. The present work highlights the use of the ethanolic extract of the Passiflora edulis peels as a natural acid-base indicator in acid-base titrations. The Passiflora edulis fruits were identified, washed, cleaned by distilled water, peeled and the 50gm of the purple peels were soaked in 100 mL of 97% ethanol for about 24 hours. The resulting solution was filtered using Whatman no.4 filters. The resulted ethanolic extract was tested for its acid base indicator properties and found to turn pink and green in acidic and basic media respectively. The extract was then used as an acid-base indicator for strong acid versus strong base and strong acid versus weak base titrations. For comparison purposes, Phenolphthalein and methyl orange indicators were used in the same titrations as for the Passiflora edulis extract. The experimental data obtained from both titrations using the three indicators were analysed using ANOVA and results showed that there was no difference between the titre values of the Passiflora edulis indicator and the other two indicators. Therefore, the indicator was found to be a potential substitute for methyl orange and phenolphthalein for titrations of strong acid versus weak base and strong acid versus strong base. Hence, Passiflora edulis peels extract as a natural indicator is found to be a very useful, readily available, non-hazardous, economical, simple to prepare and accurate for the acid-base titrations.