Determination of Sulphated Ash

Equipment : 1.Silica or Platinum crucible.

                      2.Desiccator.

Procedure:  Heat a silica or platinum crucible to redness for 10 minutes, allow to cool in a desiccator and weigh. 

Take 1.0 gm of the substance and weight the crucible . 

Ignite, gently at first, until the substance is thoroughly charred. 

Cool, moisten the residue with 1 ml of Sulphuric acid , heat gently until the white fumes are no longer evolved and ignite at 800⁰ ± 25⁰C until all black particles have disappeared. 

Conduct the ignite in a place protected from air currents. 

Allow the crucible to cool, add a few drops of Sulphuric acid and heat. 

Ignite as before, allow to cool and weigh. 

Repeat the operation until two successive weighing do not differ by more than 0.5 mg.