Quality Control

Quality control or standardization of crude drug means confirmation of its identity and determination of its quality and purity and detection of nature of adulterant by various parameters like morphological, microscopical, physical, chemical and biological observations.

Adulteration

Adulteration is defined as partial or complete replacement of original crude drug with impure, cheap, filthy, defective, harmful or putrid substances. In simple terms adulteration means debasement of original materials. The substances which are added or replaced are known as adulterants.

The adulterants generally do not possess any chemical or therapeutic properties but only resembles the original drug in respect to its morphological appearance.

An adulteration of a drug may be deliberate or accidental.

Reasons for Adulteration

Following are the reasons for crude drug adulteration:

1. Scarcity of the drug.
2. High price of the drug in the market, Eg: Clove(लवंग), cinnamon(दालचिनी), cardamom(वेलची).
3. Adulteration is very common with the contraband drugs/drug which are sold illegally, Eg: Opium(अफू).

Methods of Drug Adulteration

1. Deliberate Adulterations

The following are the various types of deliberate adulterations:

1. By means of artificially manufactured substances.
2. By means of inferior commercial varieties of drugs.
3. By means of exhausted drug.
4. By means of superficially similar inferior natural items.
5. By means of vegetative part of the same plant.
6. By means of toxic materials.
7. Adulteration of powders.

i. By means of artificially manufactured substances

In this type of adulteration, the original substances are adulterated by materials that are artificially manufactured. The materials are prepared in a way that their general form and appearance resemble the original crude drug morphologically.

Examples:

• Artificial invert sugar is used in place of honey.
• Paraffin wax coloured yellow and is been substituted for beeswax.
• Bass-wood is cut exactly the required shape of nutmeg(जायफळ) and used to adulterate nutmeg.

ii. By means of inferior commercial varieties

In this type of adulteration, the original drugs are substituted using inferior quality drugs that may be similar in morphological characters, chemical constituents or therapeutic activity.

Examples:

• Arabian senna, obovate senna and provence senna are used to adulterate senna. (Marathi names of Senna - Bhitarvada, Mulkacha, सोनमुखी Sonamukhi)
• Medicinal grade ginger being adulterated with cochin, african and japanese ginger.

iii. By means of exhausted drugs

In this type of substitution, the active medicaments of the main drugs are extracted out and are used again. this could be done for the commodities that would retain its shape and appearance even after extraction, or the appearance and taste could be made to the required state by adding coloring or flavoring agents. This technique is frequently adopted for the drugs containing volatile oil, such as clove, Fennel, etc.

Examples:

• After extraction, Saffron(केसर, Kesar) and red rose petals are recolored by artificial dyes.
• The bitterness of exhausted gentian is restored by adding aloes.

iv. By means of superficially similar inferior natural substances

Here the adulterants/ substituents used may be morphologically similar but will not be having any relation to the genuine article in their constituents or therapeutic activity.

Examples:

• Ailanthus leaves are substituted for belladonna.
• mixing of dried papaya seeds with black pepper
• The expensive spice saffron is frequently adulterated with the dried petals of the safflower

v. By means of the vegetative part of the same plant

The presence of vegetative parts of the same plant are mixed with the drug in excessive amount due to their resemblance in morphology and sometimes constituents.

Examples:

• Clove buds are often adulterated with clove stalks
• The dried leaflets of Cassia senna adulterated with excessive amounts of the stem portions of the same plant.

vi. By means of toxic materials

In this type of adulteration, the adulterants are toxic in nature and may be harmful to the body if taken internally. They are mixed due to their morphological resemblance.

Examples:

• Amber coloured glass pieces in colophony.
• Sudan Dyes in Chili Powder.
• Lead shots in opium.
• Limestone in Asafoetida

vii. Adulteration of powders

Powdered drugs are found to be adulterated very frequently. Adulterants used for powders are generally powdered waste products of a suitable colour and density.

Examples:

• Brick powder mixed with powdered barks.

2. Undeliberate Adulteration

Undeliberate adulteration is the unintentional mixing of a product with other substances, which is also known as indirect or unintentional adulteration. Unintentional adulteration may occur due to the following reasons.

1. Confusion in vernacular names between indigenous systems of medicine and local dialects.
2. Lack of knowledge about the authentic plant.
3. Non availability of the authentic plant.
4. Similarity in morphology/aroma.
5. Careless collection.
6. Other unknown reasons.

Evaluation of Crude Drugs

Evaluation of a drug ensure the identity of a drug and determines the quality and purity of drugs.

• Identity - identification of biological source of the drug.
• Quality - the quantity of the active constituents present.
• Purity - the extent of foreign organic material present in a crude drug.

There are five methods by which the drug can be evaluated:

1. Morphological/Organoleptic Evaluation
2. Microscopical Evaluation
3. Chemical Evaluation
4. Physical Evaluation
5. Biological Evaluation

1. Morphological/Organoleptic Evaluation

Organoleptic evaluation means the study of drugs using organs of senses. It refers to the methods of analysis like colour, odour, taste, size, shape and special features, such as touch, texture, etc. Obviously, the initial sight of the plant or extract is so specific that it tends to identify itself. If this is not enough, perhaps the plant or extract has a characteristic odour or taste. The study of form of a crude drug is morphology while description of the form is morphography.

Examples:

• Brown colour: Cinnamon
• Aromatic odour: Umbelliferous fruits (e.g., Fennel, coriander, caraway, dill)
• Sweet taste: Liquorice
• Fractured surface: Cinchona
• Wavy shape: Rauwolfia
• Size (7-8mm width, 25-60mm length): Senna leaf
• Quills (tightly rolled): Cinnamon
• Conical Shape: Aconite
• Pungent taste: Capsicum, Ginger

2. Microscopical Evaluation

Every species has a unique anatomy, the study of which helps us in their identification process. Microscopic evaluation is useful for the organized drugs (i.e. drugs having cellular structure). T. S. & L.S. of the drugs are observed under the microscope with the help of the staining agent.

Special attention is given to the type of tissues, their arrangement, presence or absence of special substances like calcium oxalate crystals, starch grains, size and shape of starch grains, cell contents etc.

Methods & Techniques

Powder Microscopy: Examining a powdered drug sample to see cell fragments, fibers, and inclusions.

Histological Sections: Preparing transverse sections (cross-sections) and longitudinal sections for detailed tissue study.

Leaf Constants: Quantitative measures like stomatal number, stomatal index, vein islet number, and palisade ratio for identification.

• Stomatal number: average number of stomata per sq. mm of epidermis of the leaf.
• Stomatal index: percentage of stomata (pores for gas exchange) compared to the total number of epidermal cells (including stomata) on a leaf surface
• Vein-islet number: It is defined as the number of vein islet per sq.mm of the leaf surface midway between the midrib and the margin.
• Veinlet termination number: It is defined as the number of veinlet termination per sq. mm of the leaf surface midway between midrib and margin.
• Palisade ratio: It is defined as the average number of palisade cells beneath each epidermal cell in powders.

Quantitative microscopy (Lycopodium spore method)

It involves mixing a known weight of the drug sample with a known weight of uniform Lycopodium spores, making a suspension with a suspending agent, and then counting the number of characteristic drug particles versus the number of Lycopodium spores in a set number of microscopic fields.

3. Chemical Evaluation

Chemical evaluation of crude drugs involves qualitative tests (like Dragendorff\'s for alkaloids, foam test for saponins) and quantitative analysis (titrimetry, chromatography) to identify and measure active compounds. It ensures purity and therapeutic quality through techniques like spectrophotometry, HPLC, and TLC, complementing physical & microscopic methods to detect adulteration and confirm identity. These methods confirm the presence of essential phytochemicals (tannins, glycosides, terpenes, etc.) and determine overall quality for medicinal use.

Key Methods in Chemical Evaluation

Phytochemical Screening (Qualitative Tests): Uses specific reagents to detect major chemical groups.

Alkaloids: Dragendorff\'s test (orange-red ppt), Mayer\'s test (creamy ppt).

Glycosides: Keller-Kiliani test, Molisch test, Benedict\'s test.

Tannins: Ferric chloride test, Lead acetate test, Goldbeater\'s skin test.

Saponins: Foam test (persistent foam).

Fixed Oils/Fats: Oil stain test, solubility in petroleum ether.

Proteins/Amino Acids: Ninhydrin test, Biuret test.

Quantitative Tests & Assays:
Measures the exact amount of constituents.
Gravimetry/Titrimetry: For specific group assays (e.g., alkaloids, tannins).
Spectrophotometry (UV-Vis, Fluorescence): Estimates quantities of flavonoids, glycosides, etc., by measuring light absorption or fluorescence.

Chromatographic Techniques:
Separates complex mixtures to identify/quantify components.
Thin Layer Chromatography (TLC): Rapid screening.
High-Performance Liquid Chromatography (HPLC): Precise quantification.
Gas Chromatography (GC): For volatile compounds.

4. Physical Evaluation

Physical evaluation measuring specific physical properties that help quantify purity and quality. physical evaluation uses objective measurements (moisture, solubility, ash, viscosity, etc.) to determine purity and quality. physical involves more instrumental/quantitative analysis.

Moisture Content:
Amount of water present in the drug.

Ash Value:
Inorganic residue left after burning the drug.

Solubility:
How much of the drug dissolves in different solvents (water, alcohol, ether).

Foreign Organic Matter:
Percentage of unwanted materials (stems, stones, insects, mold).

Extractive Value:
Amount of active constituents extracted by solvents (water/alcohol).

Volatile Oil Content:
Quantity of essential oils present. Important for aromatic drugs like clove, cinnamon, fennel.

Melting Point / Boiling Point:
Temperature at which the drug melts or boils.

Optical Rotation:
Ability of a drug to rotate plane-polarized light. Helps identify sugars, alkaloids, and resins.

Refractive Index:
How much light bends when passing through the drug or its extract. Used mainly for oils and resins.

Viscosity:
Thickness or flow resistance of liquid extracts or oils.

Specific Gravity:
Density of liquid drugs compared to water.

Flow Properties:
How easily powdered drugs flow. Helps in processing and shows physical quality of the powder.

Biological Evaluation of Crude Drugs

Biological evaluation of crude drugs assesses their pharmacological activity, potency, and safety on living systems (animals, tissues) when chemical methods are insufficient. It involves tests such as toxicity studies (e.g., lethal dose in mice) and functional assays (e.g., blood sugar reduction in diabetic rats) to compare drug effects against a standard, ensuring quality and identifying true medicinal value beyond mere identification.

Common Biological Methods

Toxicological Tests:
Purpose: Determine safety, effective dose (ED), and lethal dose (LD).

Symptomatic / Functional Tests:
Purpose: Observe drug effects on symptoms or physiological functions.

Examples:
Hypoglycemic: Induce diabetes in rats, then check if the drug lowers blood glucose.
Anti-inflammatory: Induce swelling in rats (carrageenan model) and measure reduction.
Hepatoprotective: Induce liver damage in rats and observe protection or recovery.

Tissue / Organ Methods (Isolated Organ Assay):
Purpose: Test drug action on specific isolated tissues or organs.
Example: Using isolated rabbit intestine to test antispasmodic activity.