Determination of sulphated Ash

Title: Determination of sulphated Ash

 

1. Objective: To measure the amount of residual substance in the sample.

 

2. Principle:

• The sulphated ash test to measure the amount of residual substance not volatilized from a sample when the sample is ignited in the presence of sulfuric acid. The test is usually used for determining the content of inorganic impurities in an organic substance.
• The total ash (ash) test is to measure the amount of residual substance not volatilized from a sample when the sample is ignited at 600-800°C.

3. Procedure:

Heat a silica or platinum crucible to redness for 10 minutes, allow to cool in a desiccator and weigh. Unless otherwise specified in the individual monograph, transfer to the crucible 1 g of the substance being examined and weigh the crucible and the contents accurately. 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 800° ± 25° until all black particles have disappeared. Conduct the ignition 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.

 

Calculations:

Weight of empty silica or platinum crucible:  W₁

Weight of silica or platinum crucible+ sample: W₂

Weight of sample:  W₃ (W₂ – W₁)

Weight of silica or platinum crucible+ ash: W₄

Weight of ash: W₅ (W₄ – W₁)

% Sulphated Ash:    W₅  x 100

W₃

 

 

---

“End of Document”