Objectives of filtration MCQs With Answer

Objectives of filtration MCQs With Answer is an essential revision resource tailored for B. Pharm students preparing for exams and practicals. This focused guide explains the primary objectives of filtration—clarification, sterilization, product recovery, and removal of particulate matter—while reinforcing concepts like depth vs membrane filtration, filter aids, pore size selection, filter validation and integrity testing. It emphasizes critical parameters such as flux, transmembrane pressure, cake formation and fouling control to help you master both theory and pharmaceutical applications. Clear, targeted MCQs with explanations strengthen problem-solving and application skills in pharmaceutical manufacturing and quality control. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which of the following is a primary objective of filtration in pharmaceutical processing?

• Increase electrical conductivity of solution
• Change chemical composition of drug
• Remove particulate contaminants
• Reduce solution pH

Correct Answer: Remove particulate contaminants

Q2. Which filtration method is most commonly used for sterilizing heat-sensitive liquid pharmaceuticals?

• Autoclaving
• Membrane (0.22 µm) filtration
• Dry heat sterilization
• UV irradiation

Correct Answer: Membrane (0.22 µm) filtration

Q3. Depth filters primarily retain particles by which mechanism?

• Surface sieving only
• Adsorption, interception and entrapment within the matrix
• Chemical reaction with solute
• Electrostatic precipitation in gas phase

Correct Answer: Adsorption, interception and entrapment within the matrix

Q4. What does the term “sterilizing-grade filter” generally refer to?

• A filter rated to remove viruses only
• A depth filter for coarse solids
• A membrane filter with pore size around 0.22 µm
• A filter with antibacterial coating

Correct Answer: A membrane filter with pore size around 0.22 µm

Q5. Which filter aid is commonly used to improve filtration of fine particles?

• Sodium chloride
• Diatomaceous earth (Celite)
• Polyethylene glycol
• Glycerin

Correct Answer: Diatomaceous earth (Celite)

Q6. What is the main advantage of crossflow (tangential) filtration over dead-end filtration?

• Higher chemical reactivity
• Reduced fouling and continuous operation
• Lower initial equipment cost always
• Complete removal of dissolved salts

Correct Answer: Reduced fouling and continuous operation

Q7. Which parameter describes the liquid flow per unit membrane area per unit time?

• Transmembrane pressure
• Flux (e.g., L/m2·h)
• Cake resistance
• Porosity

Correct Answer: Flux (e.g., L/m2·h)

Q8. Darcy’s law for filtration relates flow rate to which two factors primarily?

• Solution color and viscosity
• Transmembrane pressure and resistance
• Filter brand and operator skill
• Ambient humidity and temperature

Correct Answer: Transmembrane pressure and resistance

Q9. What is “cake resistance” in the context of filtration?

• Resistance offered by the filter membrane only
• Resistance to flow created by accumulated solids on the filter
• Electrical resistance of the slurry
• Resistance of solvents to dissolution

Correct Answer: Resistance to flow created by accumulated solids on the filter

Q10. Which test is commonly used for integrity testing of sterile membrane filters after sterilization?

• pH test
• Bubble point test
• UV absorbance test
• Viscosity measurement

Correct Answer: Bubble point test

Q11. Which of the following is a typical pore size for HEPA filters used in cleanrooms?

• 10 µm
• 0.3 µm (99.97% efficiency)
• 50 µm
• 5 mm

Correct Answer: 0.3 µm (99.97% efficiency)

Q12. In filtration, what does “nominal retention” mean?

• Guaranteed 100% removal of particles of specified size
• Approximate percentage removal for a range of particle sizes
• Retention only at high temperature
• Retention of dissolved molecules

Correct Answer: Approximate percentage removal for a range of particle sizes

Q13. Which filter type is best suited for clarification of suspensions with high solid load?

• Ultrafiltration membranes for proteins
• Filter press or plate and frame filters
• Gas chromatography columns
• Membrane cartridges for sterile liquids

Correct Answer: Filter press or plate and frame filters

Q14. What is the purpose of pre-coating a filter with filter aid?

• To chemically react with active ingredient
• To create a permeable cake that prevents membrane blinding
• To reduce solvent evaporation
• To increase solution ionic strength

Correct Answer: To create a permeable cake that prevents membrane blinding

Q15. Which membrane material is commonly used for sterile filtration of aqueous pharmaceutical solutions?

• Cellulose acetate and polyethersulfone (PES)
• Glass wool
• Stainless steel mesh
• Activated carbon

Correct Answer: Cellulose acetate and polyethersulfone (PES)

Q16. Which factor does NOT significantly influence filtration rate?

• Viscosity of the liquid
• Transmembrane pressure
• Color of the filter housing
• Cake porosity

Correct Answer: Color of the filter housing

Q17. What is the main objective of filter validation in pharmaceutical manufacturing?

• To establish cleaning schedules only
• To ensure consistent performance and microbial safety
• To improve aesthetic appearance of equipment
• To reduce manufacturing costs by cutting materials

Correct Answer: To ensure consistent performance and microbial safety

Q18. Which term describes filters that remove particles by a defined pore-size exclusion?

• Depth filters
• Membrane (screen) filters
• Centrifuges
• Settling tanks

Correct Answer: Membrane (screen) filters

Q19. Which operation is used to remove residual mother liquor from a cake after filtration?

• Cake washing
• Autoclaving
• Lyophilization only
• Chromatography

Correct Answer: Cake washing

Q20. What is the effect of increasing transmembrane pressure in dead-end filtration (initially)?

• Decrease in initial flux only
• Increase in flux until fouling/cake formation reduces gains
• Immediate membrane dissolution
• No change in filtration performance

Correct Answer: Increase in flux until fouling/cake formation reduces gains

Q21. Which filtration equipment is commonly used for continuous solids-liquid separation in industry?

• Plate and frame filter press only for batch
• Rotary vacuum drum filter
• Thin layer chromatography
• Analytical balance

Correct Answer: Rotary vacuum drum filter

Q22. Absolute retention rating of a filter indicates:

• Approximate particle removal over a range
• Guaranteed minimum removal of particles at specified size
• Electrical conductivity of the filter
• Only the flow rate of the filter

Correct Answer: Guaranteed minimum removal of particles at specified size

Q23. Which is a common cause of membrane filter failure during sterilizing filtration?

• Proper prefiltration
• Excessive differential pressure causing rupture
• Use of validated sterilizing filters
• Appropriate integrity testing

Correct Answer: Excessive differential pressure causing rupture

Q24. Which integrity test assesses the largest pore capable of passing air at a set pressure?

• pH test
• Bubble point test
• Membrane color test
• Gram staining

Correct Answer: Bubble point test

Q25. What is the benefit of using filter cartridges in final sterile filtration?

• They change solution chemical composition
• They provide consistent sterile retention and scalable throughput
• They act as preservatives
• They remove dissolved small molecules selectively

Correct Answer: They provide consistent sterile retention and scalable throughput

Q26. Which process reduces fouling by reversing flow through a membrane?

• Crossflow filtration
• Backwashing (backflushing)
• Settling
• Gel permeation

Correct Answer: Backwashing (backflushing)

Q27. Which filtration method is preferred for concentrating macromolecules like proteins?

• Microfiltration with 10 µm pores
• Ultrafiltration (membrane with molecular weight cutoff)
• Paper filtration
• Gravity decantation

Correct Answer: Ultrafiltration (membrane with molecular weight cutoff)

Q28. What role does viscosity play in filtration of pharmaceutical solutions?

• Higher viscosity increases flux
• Higher viscosity decreases filtration rate
• Viscosity has no effect
• Viscosity changes filter pore size

Correct Answer: Higher viscosity decreases filtration rate

Q29. Which of the following is a common criterion when selecting filter pore size for sterile filtration?

• Particle color
• Bacterial challenge size and sterility assurance level
• Operator preference only
• Ambient light level

Correct Answer: Bacterial challenge size and sterility assurance level

Q30. During filtration, what is “blinding” of a membrane?

• Complete chemical dissolution of membrane
• Blocking of membrane pores by particles on the surface
• Increase in membrane transparency
• Sterilization of membrane

Correct Answer: Blocking of membrane pores by particles on the surface

Q31. Which analytical measure assesses a solution’s tendency to clog a filter?

• Filterability or specific cake resistance tests
• Melting point
• Refractive index only
• Electrical current

Correct Answer: Filterability or specific cake resistance tests

Q32. Which is NOT an objective of cake washing in pharmaceutical filtration?

• Remove mother liquor impurities
• Replace solvent with wash solvent
• Increase residual solvent concentration intentionally
• Improve purity of recovered solid

Correct Answer: Increase residual solvent concentration intentionally

Q33. What is the function of a pre-filter in series with a final sterile filter?

• To chemically alter active ingredient
• To capture larger particles and extend life of final filter
• To sterilize by heat
• To color the filtrate

Correct Answer: To capture larger particles and extend life of final filter

Q34. Which membrane property is crucial for compatibility with organic solvents?

• Color of membrane
• Chemical resistance of membrane material
• Electrical conductivity
• Magnetic susceptibility

Correct Answer: Chemical resistance of membrane material

Q35. Which filtration technique is used for removal of endotoxins or very small contaminants?

• Microfiltration with 10 µm pores
• Ultrafiltration or nanofiltration
• Gravity filtration on paper
• Decantation

Correct Answer: Ultrafiltration or nanofiltration

Q36. What is a common validation parameter for sterile filtration of injectable solutions?

• Filter color change
• Bioburden and bacterial retention challenge
• Employee height
• Packaging artwork

Correct Answer: Bioburden and bacterial retention challenge

Q37. Which of the following best describes “tortuous path” in depth filters?

• Straight channels through membrane
• Complex winding pathways that trap particles
• Electrically charged fibers only
• Completely open pores with no capture

Correct Answer: Complex winding pathways that trap particles

Q38. Which operational change can help reduce fouling in membrane filtration?

• Lowering crossflow velocity
• Increasing crossflow velocity and periodic backflush
• Removing prefilters permanently
• Decreasing temperature to near freezing

Correct Answer: Increasing crossflow velocity and periodic backflush

Q39. What is the expected effect of adding a suitable filter aid to a suspension before filtration?

• Reduce cake permeability
• Improve filtrate clarity and increase filtration rate
• Convert suspension to solution instantly
• Increase dissolved impurities

Correct Answer: Improve filtrate clarity and increase filtration rate

Q40. Which filter configuration is commonly used for final sterile filtration of small batches in the lab?

• Large plate and frame press
• Syringe filter or small cartridge filter
• Rotary vacuum drum for bulk solids
• Centrifuge for sterilization

Correct Answer: Syringe filter or small cartridge filter

Q41. Which parameter indicates the ease with which a cake layer allows liquid to pass?

• Cake porosity/permeability
• Filter color
• Operator’s skill level only
• Ambient noise

Correct Answer: Cake porosity/permeability

Q42. When selecting a membrane for protein filtration, what is important to consider?

• Membrane hydrophobicity/hydrophilicity and nonspecific adsorption
• Membrane color
• Only the cost regardless of binding
• Magnetic properties

Correct Answer: Membrane hydrophobicity/hydrophilicity and nonspecific adsorption

Q43. Which technique is suitable for sterilizing heat-stable but particulate-laden liquids?

• 0.22 µm sterile filtration
• Autoclaving if compatible; otherwise filtration preceded by clarification
• Exposure to daylight
• Adding sugars to stabilize

Correct Answer: Autoclaving if compatible; otherwise filtration preceded by clarification

Q44. What is the main disadvantage of very fine pore filters (e.g., 0.1 µm) for sterile filtration?

• They are always cheaper
• Higher transmembrane pressure and faster clogging
• They dissolve rapidly
• They increase microbial load

Correct Answer: Higher transmembrane pressure and faster clogging

Q45. Which cleaning method is commonly used for membrane filters to restore performance?

• Mechanical scraping that damages membrane
• Chemical cleaning (CIP) and controlled backwashing
• Leaving membrane to air-dry indefinitely
• Exposing to strong acids without validation

Correct Answer: Chemical cleaning (CIP) and controlled backwashing

Q46. Which statement about prefiltration is TRUE?

• Prefiltration is unnecessary if final filter is 0.22 µm
• Prefiltration protects the final sterile filter by removing larger particulates
• Prefiltration always sterilizes the product
• Prefiltration replaces the need for integrity testing

Correct Answer: Prefiltration protects the final sterile filter by removing larger particulates

Q47. Which factor is critical when filtering biologics to avoid product loss?

• Using highly adsorptive membrane without testing
• Selecting low-binding membrane materials and validating recovery
• Filter temperature above protein denaturation point
• Filtering at extremely high shear rates always

Correct Answer: Selecting low-binding membrane materials and validating recovery

Q48. Which parameter is typically monitored during scale-up of filtration processes?

• Operator eye color
• Flux, transmembrane pressure and specific cake resistance
• Only the brand logo on filters
• Lamp wattage in the lab

Correct Answer: Flux, transmembrane pressure and specific cake resistance

Q49. What does “filter qualification” in GMP context include?

• Documenting vendor marketing materials only
• Installation, operational and performance qualification (IQ/OQ/PQ)
• Only aesthetic inspection of equipment
• Random staff surveys

Correct Answer: Installation, operational and performance qualification (IQ/OQ/PQ)

Q50. Which practice improves assurance of sterility after membrane filtration?

• Omitting integrity testing to save time
• Performing post-filtration integrity tests and validated aseptic handling
• Storing filtered solution at room temperature indefinitely without control
• Using a visibly clean but unvalidated filter

Correct Answer: Performing post-filtration integrity tests and validated aseptic handling

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