Use of Ipomoea involucrata B. flower as metallochromic indicator for complexometric titrations

The present work highlights the use of Ipomoea involucrate B. flower extract as a complexometric indicator in complex formation between the EDTA and the following metal solutions (Cu2,+ Ba2,+ Hg2+, Fe3+, and Bi3+). Ipomoea involucrate is a species of the Ipomoea genus, belonging to the family Convolvulaceae. This natural indicator was extracted in 2M HCl at 100 0C for 30-40 minutes, cooled and the extract filtered and extracted with ethyl acetate and the pigment extracted with amyl alcohol which was separated and concentrated over a water bath. The flower extract was screened for its use as an metallochromic indicator at different pHs in metal solutions of Cu2,+ Ba2,+ Hg2+, Fe3+, and Bi3+.This natural indicator from the results obtained gave sharp intense color change at the equivalence point of complex formation between the metals and the EDTA at both acidic and alkaline pHs in the metal solution of Cu2+ and Fe3+ and that with different amount of EDTA used in the titration, which increased as the pH value increased, while the ipomoea indicator gave sharp intense color change at the equivalence point of complex formation between the metals and the EDTA at alkaline pHs in the metal solution of Ba2+, Hg2+ and Bi3+ at pH > 10. Natural flower indicators could take the place of the synthetic metallochromic indicators currently used in conventional laboratories because these flower extracts have excellent performance with sharp and intense color change in end points during the complexometric titrations and simple, cost-effective and environmentally friendly extraction methods.\