Study Set Content:
residue remaining after incineration is the (blank) of the drug.
ash content
- Inorganic salts of carbonates, phosphates, silicates of sodium, potassium, calcium and magnesium.
Ash value
- is a criterion to judge the identity or the purity of the crude drug.
Ash value
Inorganic salts of carbonates
- phosphates, silicates of sodium, potassium, calcium and magnesium.
is indicative of contamination, substitution, adulteration or carelessness in preparing the crude drug for marketing.
high ash value
is used as a basis for the identity and cleanliness of a drug
Ash content
- This also gives information about adulteration with inorganic matter.
Ash content
- is a measure of the amount of inorganic matter present as impurity.
The ash or residue yielded by organic matter
Ash value can be determined by three different methods:
Total Ash
Acid insoluble ash
Water soluble ash
used to measure the total amount of material remaining after incineration
Total ash
is the residue obtained after boiling the total ash with dilute HCl and igniting the remaining insoluble matter
Acid insoluble ash
is the difference in weight between total ash and residue after treatment of total ash with water
Water soluble ash
Total Ash methods
Weigh accurately about 3gms of the powdered drug in a tared silica crucible
Heat at 450 degrees until free from carbon
Cool and weigh
Acid insoluble ash methods
Total Ash
Add 10 mL 3N HCL and boil for 5 mins.
Filter through ashless filter paper
Ignite at 450 degrees
Cool and Weigh
Water soluble Ash methods
Total Ash
Add 10 ml water and boil for 5 mins.
Filter through ashless filter paper
Ignite at 450 degrees
Cool and weigh
Six methods used to determine water content
Karl Fisher Titrimetry
Azeotropic Distillation (USP) / Moisture method by toluene distillation (NF) – Xylene method
Gravimetric Method – Method of Choice
Dew point
Electrolytic hygrometric
- 1mL of KFR = 15mL H2O
Karl Fisher Titrimetry
Moisture is removed from the sample by distillation as an azeotrope (constant boiling point mixtures) with a solvent.
Azeotropic Distillation (USP) / Moisture method by toluene distillation (NF) – Xylene method
- Method of Choice
- Dried at 105˚C for 5 hours
Gravimetric Method
- For drugs containing no constituents, other than water, volatile @ 105˚C
For drugs containing ether-soluble constituents volatile @ 105˚C
- Gravimetric Method – Method of Choice
