Quality control of crude drug and quantitative microscopy of crude drug

Quality control of crude drug

Quality control is a system of maintaining standard in product by ensuring it identify, purity, and its quality. Quality control of crude drugs is essential for maintaining safety and efficacy. It involves the use of various techniques to ensure that the drugs are free from contamination, adulteration and degradation. Quality control also helps to determine the purity and potency of the drugs. Quality control includes both physical and chemical tests that can be used to detect any impurities in the crude drug.

Evaluation method of crude drug

1. Morphological evaluation
2. Microscopic evaluation
3. Chemical evaluation
4. Physical evaluation
5. Biological evaluation

1. Morphological evaluation

It is a technique of qualitative evaluation based on the morphological and sensory priorities. In the morphological evaluation, the drugs are identified on the basis of size, shape and other specific features. In the organoleptic evaluation, the drugs are identifying the help of sensory organ like color, odor, touch, texture and taste.

2. Microscopic evaluation

In this method, the organized drugs are used to identify by its histological and morphological character (cell arrangement). The characteristics like trichomes (hairy like structure present in Datura), fibers, vascular bundle, xylem, phloem & other cell contents can be studied under this.

3. Chemical evaluation

In which drugs are evaluated with the help of chemical test. Determination of the active constituent present in a drug by chemical test.

1. Qualitative test: quality determine
2. Quantitative test: quantity determine
3. Chemical assay: measure the amount of a specific substance.
4. Instrumental analysis: functional group determine by chromatography & spectroscopy.

4. Physical evaluation

The physical evaluation method for crude drug is as follow:

1. Moisture content

The percentage of active constituent of crude drug is expressed in air dry basic. It should be minimized to prevent the decomposition of crude drug or due to chemical change and due to microbial contamination. The moisture content is determined by the hearing the drug at 105°C in oven to a constant weight.

2. Viscosity

The viscosity of liquid drug is constant at a given temperature.

3. Melting point

To check the purity of drug this parameter is used for pure chemicals, phytochemical. Melting point is very sharp & constant.

4. Solubility

An adulterant can be detected in a crude drug by solubility studies like alkaloids bases are soluble in organic solvent.

5. Optical rotation activity

It is determined by using Na lamp as a light source at 25°C. Certain substance are found to have the property of rotating plane polarized light in the pure state.

5. Biological evaluation

It is the important, most reliable but costly evaluation of drugs. These methods are performed on living animals or experimental animals like rat, mice, rabbit, cat etc, isolated organ and tissues and according as bio assay or biological assay. The plant extracts are used here to determine the pharmacological activity, potency & toxicity.

In this method following activities are checked:

1. Antidiuretic activity
2. Analgesic activity
3. Antiulcer activity
4. Anti-inflammatory activity
5. Anti piratic activity

Quantitative microscopy of crude drug

Lycopodium spore method

It is an analytical technique used for powdered drug; it determines the number of spore present in a mg of sample. Here lycopodium is taken as a reference or standard drug about 94000 spores are found in 1mg of powder lycopodium. A powdered drug is evaluated by lycopodium spore method-

Example:- The percentage purity of ginger powder is calculated by:


N = no. of characteristic structure in 26 feet.
W = weight of lycopodium in mg
S = number of lycopodium spores
M = weight of sample in mg
P = 2,86,000 in case of ginger starch grain powder

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