Isolation and Identification of a Pigment from Grape for Use as Acid-Base Indicator.

This paper deals with the extraction of a pigment (Malvidin-3-fructoside) from the Iraqi Kurdistan grape (Vitis vinifera L.). The extracted pigment was purified using physical methods including different chromatographic techniques (TLC, PC, PTLC and HPLC). The pure extracted pigment was identified using different techniques such as infrared (IR), ultraviolet (UV), 1H-NMR, 13C-NMR and CHN analysis.
The isolated pigment from grape was suggested to be very useful indicator for acid-base titration due to good precision and accuracy compared with commercial indicators such as methyl orange, methyl red and phenolphthalein. This pigment was also used in the preparation of indicator paper.