Determination of Ash Values


To determine the various ash values of the given cured drug.

Material required

 Silica crucible, muffle furnace, powdered drug, 0.1N HCl, Ashless filter paper, desiccator.


Ash values help determine the quality and purity of the crude drug, especially in powdered form. The object of ashing a vegetable drug is to remove all traces of organic matter which may otherwise interfere in analytical determination. On incineration, crude drugs normally leave ash usually consisting of carbonates, phosphates, and silicates of sodium, potassium, calcium, magnesium.

Ash values

The total ash of crude drug reflects the care taken in its preparation. Acid insoluble ash is the residue after extracting the total ash or sulfated ash with HCl, while water-soluble ash represents the total part of ash that is soluble in water. Water-soluble ash is a good indicator of the previous extract of water-soluble components of the crude drug. It also reflects on incorrect preparation or processing of crude drugs. Acid insoluble ash indicates the siliceous or earthly material contamination of crude drugs. A higher limit of acid-insoluble ash is imposed, especially in-case where silica may be present or when the calcium oxalate content of the drug is very high.


a). Determination of total ash value

1. Weigh accurately about 5 gm of the powdered drug in a tarred silica crucible.

2. Incinerate the powdered drug by gradually increasing the heat by using a Muffle furnace until free from carbon and cool. Keep it in a desiccator.

3. Weigh the ash and calculate the percentage of total ash concerning the air-dried sample.

b). Determination of acid-insoluble ash value

 1.  Boiled the total ash obtained as above for 5min with 25 ml of Dil HCl.

2.  Filter and collect the insoluble matter on ashless filter paper. Wash the filter paper with hot water, ignite in the tarred crucible, cool, and kept in a desiccator.

3.  Weigh the residue and calculate the acid-insoluble ash of crude drug concerning the air-dried drug.

c). Determination of water-soluble ash value

1. Boil the total ash obtained as above with 25ml of water for 5min.

2. Filter through the ashless filter paper.

3. Wash the residue with hot water, and then ignite the tarred crucible by the Muffle furnace, cool and kept in desiccators.

4.  Weigh the ash obtained after incineration and calculate the water-soluble ash of the drug concerning air-dried sample.

The unpeeled variety of cured drugs should contain no more than 10% of total ash and 2.5% of acid-insoluble ash.


1.Total ash value of  crude powdered drug = 3.6 %

2.Acid insoluble ash value of crude powdered drug = 1 %

3.Water-soluble ash value of crude powdered drug = 0.78 %

Make sure you also check our other amazing Article on : Standardization of Vitamins
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