1. Make up to the mark with boric acid solution (#.#) and add # μl of #-mercaptoethanol (#.#) by syringe

2. Make up to the mark with boric acid solution (#.#.#) and add # μl of #-mercaptoethanol (#.#.#) by syringe

3. Place about 20 ml of boric acid solution in a 100 ml conical flask and place the flask under the condenser of the Kjeldahl distillation apparatus so that the delivery tube dips just below the surface of the boric acid solution.

4. The ammonia is released by the addition of sodium hydroxide solution and then distilled and absorbed in a boric acid solution.