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The Standardization of crude drug materials includes the following steps:-
1. Authentication: - Each and every step has to be authenticated.
a)      Stage of collection.
b)      Parts of the plant collected.
c)      Regional status.
d)     Botanical identity like phytomorphology, microscopical and histological analysis (characteristic of cell walls, cell contents, starch grains, calcium oxalate crystals, trichomes, fibers, vessels etc).Various histological parameter studies are:-
1. Leaf constant: - Palisade ratio, Vein islet number, Vein termination, Stomatal number, and
2. Stomatal index.
3. Trichomes
4. Stomata.
5. Quantitative microscopy.
6. Taxonomical identity.
7. Foreign matter.
8. Organoleptic evaluation.
9. Ash values and extractive values.
10. Moisture content determination.
11. Chrometographic and spectroscopic evaluation.
12. Heavy metal determination.
13. Pesticide residue.
14. Microbial contamination.
15. Radioactive contamination.
16. The stability parameters for the herbal formulations which include physical, chemical and microbiological parameters are as follow:
Physical parameters
 include color, odor, appearance, clarity, viscosity, moisture content, pH, disintegration time, friability, hardness, flow ability, flocculation, sedimentation, settling rate and ash values.

Chemical parameters include limit tests, chemical tests, chemical assays etc.

Chromatographic analysis of herbals can be done using TLC, HPLC, HPTLC, GC, UV, GC-MS, fluorimetry etc.

Microbiological parameters include total viable content, total mold count, total enterobacterial and their count. Limiters can be utilized as a quantitative or semi quantitative tool to ascertain and control the amount of impurities like the reagents used during abstraction of various herbs, impurities coming directly from the manufacturing vessels and from the solvents etc.

2. F.O.M. (Foreign organic matter)determination:
The parts of the organs of the crude drug other than those named in definition and description of drug are defined as foreign organic matter.

The maximum limit for the foreign organic matter is defined in monograph of crude drug. if it exceeds the limits, deterioration in quality of drug take place.

Weigh 100 –500 g of the drug sample to be examined or the minimum quantity prescribed in the monograph, and spread it out in a thin layer. The foreign matter should be detected by inspection with the unaided eye or by the use of a lens (6x). Separate and weigh it and calculate the percentage present.


Table 1: Determination of Foreign matter

plant parts


foreign matter limit

leaves and herbs

bearberry leaf

not more than 8%foreign matter of which NMT
5% stems and nmt 3%other organic matter

birch leaf

NMT 3%fragments  of female catkins, nmt
3% other organic matter


NMT5%stem with diameter>4mm, nmt
2% other organic matter

fruits and seeds

hawthrown seeds

NMT2% foreign matter, nmt 5% deteriorated
false fruits

psyllium seeds

NMT 1% foreign matter including
greenish unripe fruit.



NMT 2 5 foreign matter


NMT 1% foreign matter

Loss on drying
The test determine both water and volatile matter in the crude drug. loss on drying is the loss of mass expresed as w/w and can be determined by following procedure :

Method: Procedure set forth here determines the amount of volatile matter (i.e., water drying off from the drug). For substances appearing to contain water as the only volatile constituent, the procedure given below, is appropriately used. Place about 10 g of drug (without preliminary drying) after accurately weighing (accurately weighed to within 0.01 g) it in a tared evaporating dish. For example, for underground or unpowderdd drug, prepare about 10 g of the sample by cutting shredding so that the parts are about 3 mm in thickness. Seeds and fruits, smaller than 3 mm should be cracked. Avoid the use of high speed mills in preparing the samples, and exercise care that no appreciable amount of moisture is lost during preparation and that the portion taken is representative of the official sample. After placing the above said amount of the drug in the tared evaporating dish dry at 105º for 5 hours, and weigh. Continue the drying and weighing at one hour interval until difference between two successive weighings corresponds to not more than 0.25 per cent. Constant weight is reached when two consecutive weighings after drying for 30 minutes and cooling for 30 minutes in a desiccator, show not more than 0.01 g difference.

Table 2: Crude drug with limit for moisture content


Moisture content(%w/w)


Not more than10%


Not more than5%


Not more than8%


Not more than15%


Not more than15%

Ash value:
The residue remaining after incineration is the ash content of the drug,which simply represents inorganic salts,naturally occuring in drug or adhering to it or deliberately added to it as form of adulteration.ash value is criteria to judge the identity or purity of drug.

The ash remaining following ignition of medicinal plant material is determined by three different method which measure total ash, acid insoluble ash, water soluble ash.

Determination of Total Ash
Incinerate about 2 to 3 g accurately weighed, of the ground drug in a tared platinum or silica dish at a temperature not exceeding 450º until free from carbon, cool and weigh. If a carbon free ash cannot be obtained in this way, exhaust the charred mass with hot water, collect the residue on an ashless filter paper, incinerate the residue and filter paper, add the filtrate, evaporate to dryness, and ignite at a temperature not exceeding 450º. Calculate the percentage of ash with reference to the air-dried drug.


Table 3: Determination of Total Ash


Total ash (% w/w)


Not more than 5 %


Not more than 11%


Not more than 7 %


Not more than 3 %

Acid insouble ash:
Test measured the amount of silica present, especially as sand siliceous earth

Boil the ash obtained  for 5 minutes with 25 ml of dilute hydrochloric acid; collect the insoluble matter in a Gooch crucible, or on an ashless filter paper, wash with hot water and ignite to constant weight. Calculate the percentage of acid-insoluble ash with reference to the air dried drug.


Table 4: Acid insouble ash


Acid insoluble ash (%w/w)


Not more than 1.0


Not more than 2.0


Not more than 1.0

Water soluble ash:
Determination of Water Soluble Ash:
Boil the ash for 5 minutes with 25 ml of water; collect insoluble matter in a Gooch crucible, or on an ashless filter paper, wash with hot water, and ignite for 15 minutes at a temprature not exceeding 450º. Substract the weight of the insoluble matter from the weight of the ash; the difference in weight represents the watersoluble ash. Calculate the percentage of water-soluble ash with reference to the airdried drug.


Table 5: Water soluble ash


Water soluble ash (%w/w)


Not more than 1.7

5. Extractive value:
The extracts obtained by exhausting crude drugs are indicative of their chemical constituent(app.). taking into consideration the diversity of chemical nature and property of contents of drugs, various solvents are used for determination of extractive.

Determination of Alcohol Soluble Extractive
Macerate 5 g of the air dried drug, coarsely powdered, with 100 ml of Alcohol of the specified strength in a closed flask for twenty-four hours, shaking frequently during six hours and allowing to stand for eighteen hours. Filter rapidly, taking precautions against loss of solvent, evaporate 25 ml of the filtrate to dryness in a tared flat bottomed shallow dish, and dry at 105º, to constant weight and weigh. Calculate the percentage of alcohol-soluble extractive with reference to the air-dried drug.


Table 6: Determination of Alcohol Soluble Extractive

Alcohol soluble extractive value of some crude drug


Alcohol soluble extractive (%w/w)


Not less than 10.0


Not less than 40.0


Not less than 15.0


Not less than 3.0


Not less than 8.0

Determination of Ether Soluble Extractive (Fixed Oil Content)
Transfer a suitably weighed quantity (depending on the fixed oil content) of the air dried, crushed drug to an extraction thimble, extract with Solvent ether (or petroleum ether, b.p. 40º to 60º) in a continuous extraction apparatus (Soxhlet extractor) for 6 hours. Filter the extract quantitatively into a tared evaporating dish and evaporate off the solvent on a water bath. Dry the residue at 105º to constant weight. Calculate the percentage of ether-soluble extractive with reference to the air-dried drug.


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