Recommended procedure

Accurately weigh about 1 g of the substance, or the quantity specified in the monograph, into a suitable dish (usually platinum) and moisten with sulfuric acid (~1760 g/l) TS. Heat gently to remove the excess of acid and ignite at about 800°C until all the black particles have disappeared; again moisten with sulfuric acid (~1760 g/l) TS and re-ignite. Add a small amount of ammonium carbonate R and ignite to constant weight.