Division 6.2 Test for presence of ammoniacal nitrogen

If the presence of ammonium caseinate or other ammonium compounds is suspected, carry out the following test. Add to 1 gram of sample in a small conical flask 10 ml of water and 100 mg of magnesium oxide. Rinse down any magnesium oxide adhering to the walls and close the flask with a cork stopper, inserting a piece of moistened red litmus paper between the stopper and the neck of the flask. Mix the contents of the flask carefully and heat the flask in a water bath at 60 to 65 ^o C. If the litmus paper colours blue within 15 minutes ammonia is present, and the method is not applicable (see Section 1).