Principle |
· Borates Give A Red Colour With Curcumin (The Colouring Matter Found In Turmeric). |
Reagents |
· Calcium Oxide |
· 5N Hcl |
· 1 % Ethanolic Solution Of Curcumin (Or Turmeric Extract) |
· Oxalic Acid, Saturated |
Procedure |
· Mix The Sample With Lime (About 10 Parts To One) Or Sod Carbonate And If Necessary Moisten With Water. Dry In The Oven, Then Ash At A Dull Red Heat. A Completely White Ash Is Not Necessary. Cool, Add Water And 5 N Hcl Till The Solution Is Acidic. Filter Into A Porcelain Dish, Add 4 Drops Of Oxalic Acid Solution And 1 Ml Of Curcumin Solution And Evaporate On A Water Bath. |
· If Borates Are Present, The Residue Turns Into Bright Red Colour And Changes To Dark Green When Exposed To Ammonia Fumes |
· AOAC Official Method 970.33 Boric Acid And Borates In Food Qualitative Test, First Action 1970. |