Purification and identification of crude drugs MCQs With Answer

Purification and identification of crude drugs MCQs With Answer are essential study tools for B. Pharm students learning pharmacognosy and herbal drug standardization. This focused set covers organoleptic and microscopic evaluation, phytochemical screening, chemical tests for alkaloids, tannins and glycosides, physicochemical parameters (ash values, loss on drying, specific gravity), and purification techniques like extraction, steam distillation, recrystallization, TLC and HPLC. Emphasis on adulteration detection, chromatographic fingerprints, spectroscopic identification (UV, IR, NMR) and pharmacopoeial standards helps students master quality control and standardization of natural products. Answers with brief explanations promote deeper understanding and exam readiness and practical laboratory application.

Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the correct definition of a “crude drug”?

• A synthetic therapeutic compound produced in industry
• A purified active pharmaceutical ingredient after formulation
• A natural material of plant, animal or mineral origin used for medicinal purposes
• A laboratory reagent used for chromatographic analysis

Correct Answer: A natural material of plant, animal or mineral origin used for medicinal purposes

Q2. Which of the following is part of organoleptic evaluation of a crude drug?

• Thin layer chromatography pattern
• Color, odor, taste and texture
• Ash values and moisture content
• HPLC retention time

Correct Answer: Color, odor, taste and texture

Q3. Microscopic examination of a plant drug is primarily used to identify which features?

• Solubility and extractive values
• Stomata, trichomes, vessel elements and stone cells
• UV absorption maxima
• Specific gravity and refractive index

Correct Answer: Stomata, trichomes, vessel elements and stone cells

Q4. Which physicochemical parameter helps quantify inorganic residue in a crude drug?

• Loss on drying
• Ash value
• Extractive value
• Melting point

Correct Answer: Ash value

Q5. “Loss on drying” of a crude drug is used to determine:

• Total alkaloid content
• Volatile oil composition
• Moisture and volatile matter content
• Inorganic ash content

Correct Answer: Moisture and volatile matter content

Q6. Acid-insoluble ash mainly indicates the presence of which contaminant in a crude drug?

• Organic pesticides
• Siliceous materials like sand and silicates
• Residual solvents
• Microbial contamination

Correct Answer: Siliceous materials like sand and silicates

Q7. Which analytical technique is most often used for rapid fingerprinting of crude drugs in a pharmacognosy lab?

• Thin layer chromatography (TLC)
• Nuclear magnetic resonance (NMR)
• Gas chromatography-mass spectrometry (GC-MS)
• Polarimetry

Correct Answer: Thin layer chromatography (TLC)

Q8. Steam distillation of a plant material is primarily used to isolate:

• Alkaloids
• Volatile oils (essential oils)
• Glycosides
• Proteins

Correct Answer: Volatile oils (essential oils)

Q9. Which solvent is commonly used for defatting plant material before polar extraction?

• Methanol
• Water
• Petroleum ether
• Acetic acid

Correct Answer: Petroleum ether

Q10. Phytochemical screening of a crude drug aims to detect presence of:

• Active pharmaceutical ingredients (API) from synthetic sources only
• Biological contaminants such as bacteria
• Secondary metabolites like alkaloids, flavonoids, tannins and glycosides
• Tablet excipients

Correct Answer: Secondary metabolites like alkaloids, flavonoids, tannins and glycosides

Q11. Which reagent is classically used to detect alkaloids in crude drug extracts?

• Fehling’s solution
• Dragendorff’s reagent
• Ferric chloride
• Salkowski reagent

Correct Answer: Dragendorff’s reagent

Q12. Ferric chloride test is commonly used to detect which class of compounds?

• Alkaloids
• Carbohydrates
• Phenolic compounds and tannins
• Saponins

Correct Answer: Phenolic compounds and tannins

Q13. “Standardization” of a crude drug primarily refers to:

• Random sampling of raw material without testing
• Establishing consistent quality, purity and strength using validated tests
• Labeling the drug with traditional uses only
• Mixing multiple plant species to increase yield

Correct Answer: Establishing consistent quality, purity and strength using validated tests

Q14. Which chromatographic technique is most suitable for quantitative determination of a marker compound in a crude drug extract?

• Paper chromatography
• Thin layer chromatography (TLC) without densitometry
• High-performance liquid chromatography (HPLC)
• Simple solvent extraction

Correct Answer: High-performance liquid chromatography (HPLC)

Q15. The most commonly used stationary phase for TLC of herbal extracts is:

• Cellulose paper
• Reverse osmosis membrane
• Silica gel
• Activated charcoal

Correct Answer: Silica gel

Q16. The Rf value in TLC depends on which factors?

• Only the detection reagent used to visualize spots
• Mobile phase composition, stationary phase and compound polarity
• Temperature alone
• Only the thickness of the TLC plate

Correct Answer: Mobile phase composition, stationary phase and compound polarity

Q17. Which method is commonly used for large-scale purification and separation of components from crude plant extracts?

• Column chromatography
• Paper chromatography
• Simple filtration through cheesecloth
• Microscopy

Correct Answer: Column chromatography

Q18. Which technique is best suited for separation and analysis of volatile constituents from a crude drug?

• High-performance liquid chromatography (HPLC)
• Gas chromatography (GC)
• Paper chromatography
• Gravimetric analysis

Correct Answer: Gas chromatography (GC)

Q19. Infrared (IR) spectroscopy is primarily useful in crude drug identification for:

• Determining elemental composition only
• Identifying functional groups and characteristic bonds
• Counting number of carbon atoms directly
• Measuring moisture content

Correct Answer: Identifying functional groups and characteristic bonds

Q20. UV-visible spectroscopy is most useful for:

• Identifying inorganic contaminants
• Quantifying conjugated chromophores and measuring extractive values
• Visualizing starch grains microscopically
• Determining ash values

Correct Answer: Quantifying conjugated chromophores and measuring extractive values

Q21. Nuclear magnetic resonance (NMR) spectroscopy provides which information about a phytochemical?

• Only melting point
• Detailed structural information including carbon-hydrogen framework
• Color and odor characteristics
• Amount of inorganic ash

Correct Answer: Detailed structural information including carbon-hydrogen framework

Q22. Determination of foreign organic matter in crude drugs is performed by:

• Chemical derivatization and GC analysis only
• Physical separation, identification and weighing of contaminants
• Measuring refractive index
• Using Dragendorff’s reagent

Correct Answer: Physical separation, identification and weighing of contaminants

Q23. Microbial limit tests for crude drugs are important because:

• They determine alkaloid content
• They assess acceptable levels of microbial contamination for safety
• They replace the need for chemical assays
• They measure moisture content only

Correct Answer: They assess acceptable levels of microbial contamination for safety

Q24. To detect adulteration of powdered herbal material, which approach is most informative?

• Only organoleptic testing
• TLC fingerprinting combined with microscopic and physicochemical tests
• Weighing the powder on a balance
• Observing the powder under UV light without chromatography

Correct Answer: TLC fingerprinting combined with microscopic and physicochemical tests

Q25. Which reagent/test is used for detection of steroidal nucleus in crude drug extracts?

• Molisch’s test
• Liebermann-Burchard test
• Biuret test
• Fehling’s test

Correct Answer: Liebermann-Burchard test

Q26. Which parameter is most relevant for standardization of volatile oils from a plant source?

• Loss on drying only
• Specific gravity, refractive index and optical rotation
• Total ash value only
• Melting point

Correct Answer: Specific gravity, refractive index and optical rotation

Q27. Which test is classically used to detect presence of tannins in a crude drug?

• Dragendorff’s test
• Ferric chloride test producing blue-black or green coloration
• Biuret test for proteins
• Wagner’s reagent

Correct Answer: Ferric chloride test producing blue-black or green coloration

Q28. Which practice improves purity of an active constituent extracted from crude plant material?

• Crude maceration without solvent removal
• Sequential solvent partitioning followed by chromatographic purification
• Immediate drying at high temperature without filtration
• Mixing extracts from multiple unrelated plants

Correct Answer: Sequential solvent partitioning followed by chromatographic purification

Q29. Which pharmacopoeial parameter indicates organic volatile impurities in a crude drug?

• Acid-insoluble ash
• Loss on drying and residue on evaporation of solvent
• Microscopic characters
• Stomatal index

Correct Answer: Loss on drying and residue on evaporation of solvent

Q30. Official monographs and standards for crude drugs are found in which references?

• Textbooks only
• Pharmacopoeias and official compendia
• Internal lab notebooks only
• Product brochures from suppliers

Correct Answer: Pharmacopoeias and official compendia

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com