Module 3 - Strategic case studies in practice

128

B. Iron oxide identification Reagents Hydrochloric acid EP Potassium hexacyanoferrate (II) 5% solution Nitric acid. Procedure

If the capsule remains coloured, other than white, after the alcohol water extraction, the presence of iron oxide is indicated. Place capsule part in a micro-test tube. To this add 2 ml of distilled water and dissolve by warming the tube in a water bath at 60°C. Riter the solution through glass filter paper (Whatmann GF/A) 1 em diameter held in a mini Buchner funnel. Wash the filter paper and transfer to a test tube. Add 2 ml of hydrochloric acid to the test tube and warm in a Bunsen flame. Decant off liquid into a micro-test tube. To this liquid, add one drop of nitric acid and boil the solution. Cool the suspension and add 2 ml of potassium hexacyanoferrate (II) 5% solution. A deep blue precipitate is produced when iron oxide is present.

CJ