S.L. 437.67 Art. 3methyl red in g of boric acid Add 10 ml of to light red fix a maximum of potassium

Reagents 3.1. 20% (w/v) solution of trichloroacetic acid.

3.2. Indicator: dissolve 33 mg of bromocresol green and 65 mg of 100 ml of 95% - 96% (v/v) of ethanol.

3.3. Boric acid solution: in a 1 litre graduated flask dissolve 10 A.R. in 200 ml of 95% - 96% (v/v) ethanol and 700 ml of water. indicator (3.2.). Mix and, if necessary, adjust the colour of the solution by adding a solution of sodium hydroxide. 1 ml of this solution will of 300 µg of NH3.

3.4. Saturated potassium carbonate solution: dissolve 10 Og carbonate A.R. in 100 ml of boiling water. Leave to cool, filter.

3.5. Sulphuric acid 0ꞏ02 N.