Sulphated Ash Test Procedure (GTP) as per IP & BP

Discover the essential General Test Procedure for Sulphated Ash as outlined in IP and BP pharmacopoeia. Gain insights and improve your testing methods

Sulphated Ash as per IP & BP

1.0     Objective

    • The objective of this GTP is to describe the procedure to be used for performing Sulphated ash test.

2.0     Principle/Reaction

    • It is a quantitative measuring technique used to find out presence of inorganic impurities.
    • It can be measured in terms of % w/w of the substance being examined.

3.0     Requirements for Determining Sulphated Ash

    • As per IP/BP

    • Silica or platinum crucible
    • Sulphuric acid
    • Muffle furnace
    • Desiccator
    • Pipette
    • Analytical balance

4.0    Test Procedure for Sulphated Ash 

    • As per IP/BP
    • Ignite a suitable crucible (for example, silica, platinum, porcelain or quartz) at 600 ±  50 °C for 30 min.
    • Allow to cool in a desiccator over silica gel or other suitable desiccant and weigh.
    • Place the prescribed amount of the substance to be examined in the crucible and weigh.
    • Moisten the substance to be examined with a small amount of sulfuric acid (usually 1 ml) and heat gently at a low temperature as practicable until the sample is thoroughly charred.
    • After cooling, moisten the residue with a small amount of sulfuric acid (usually 1 ml), heat gently until white fumes are no longer evolved and ignite at 600 ± 50 °C until the residue is completely incinerated.
    • Ensure that flames are not produced at any time during the procedure.
    • Allow the crucible to cool in a desiccator over silica gel or other suitable desiccant, weigh it again and calculate the percentage of residue.
    • If the amount of the residue so obtained exceeds the prescribed limit, repeat the moistening with sulfuric acid and ignition, as previously, for 30 min periods until 2 consecutive weighing do not differ by more than 0.5 mg or until the percentage of residue complies with the prescribed limit.
    • The amount of substance used for the test (usually 1-2 g) is chosen so that at the prescribed limit the mass of the residue (usually about 1 mg) can be measured with sufficient accuracy.

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