Author(s): Jaleel Kareem Ahmed
Anthocyanin is found mainly in red beet juice, cherry, red rose. It is red color pigment with high solubility in water. It is exchangeable like cation exchanger in demineralization processes of water (hetero reaction) while with the anthocyanin juice is homogenous reaction. Addition of heavy metal salt like metal nitrate (water soluble) results in sudden precipitation of metal anthocyanin and the colour of the solution disappear slowly. The pH of the solution becomes more acidic and leads to the formation of nitric acid in which the pH reaches nearly four. No precipitations shown with sodium and potassium ions while with magnesium and calcium ions need high concentration of them. Anthocyanin can be used to purify water from poisonous metals ions.
Anthocyanin colour in acidic solution is shine red which gets changed to reddish green colour in basic solution and deep red colour in neutral solutions. so, it is suitable indicator in acid-base reaction. It is more suitable than classically used phenolphthalein indicator which is water in soluble. Irrigation of red rose plant with acidic solution like hydrochloric acid result in changing the colour of the rose from deep red to shine red, also that happen when red rose plant left in acidic atmosphere.
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