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Determine the Ash Value of Crude Drug – Pharmacognosy Practical B Pharmacy 4th Semester

Objective: To Determine Total Ash Value of Crude Drug


Ash value are helpful in determining the quality & purity of crude drugs especially in powdered form. The objective of ash-ing vegetable drug is to remove all traces of organic matter which may interferes in analytical determination.

Principle: On incineration, the crude drugs normally produce ash which is usually consisting of carbonates, phosphates and silicates of sodium, potassium, calcium and magnesium.

The total ash of a crude drug reveals the care taken during its preparation. A higher limit of acid- insoluble ash is incorporated especially in cases where silica may be present or when the calcium oxalate content of the drug is very high.


Hear Resistant Gloves, Muffle/furnace, Silica crucible, Desiccator, Ash less filter paper, Spatula & Dil. HCl, Sample of crude drugs.


  1. Take a clean, empty silica crucible and keep it in the muffle furnace for 10-15 minutes for ignition.
  2. Then, Take out the Silica crucible and keep it in desiccator for cooling for 15-20 minutes.
  3. Weigh the empty silica crucible and note the reading.
  4. Take 2 gm of crude drug sample in the silica crucible and spread with the help of spatula.
  5. Now, keep the silica crucible in muffle furnace at temperature of 450°C – 600°C for incineration of crude drug.
  6. Turn the temperature knob to 0°C after some time.
  7. Take our the silica crucible and keep it in desiccator for cooling.
  8. Weigh the silica crucible again and note the readings.
  9. Calculate the percentage of the total as in contrast to the air dried sample of the crude drug.

Determination of acid-insoluble ash

  1. Boil the total obtained ash for 5 minutes and mix 25 ml of dilute hydrochloric acid.
  2. Filter and collect the insoluble matter on a ash-less filter paper, after that wash the filter paper with hot water, ignite in tared crucible, cool and keep in desiccator.
  3. Weigh the obtained residue and calculate acid-insoluble ash of the crude drug with reference to the air dried drug.
  4. For Example: The unpeeled variety of liquorice root must contain not more than 10% of total ash and 2.5% of acid-insoluble ash.


Ash Value of given sample of crude drug is _____

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