Introduction
This quiz collection on “Qualification of Membrane Filter MCQs With Answer” is designed specifically for M.Pharm students studying MIP 202T – Scale Up & Technology Transfer. The questions focus on practical and theoretical aspects of membrane filter qualification used during aseptic processing and sterile filtration — including filter selection, validation stages (DQ/IQ/OQ/PQ), integrity testing (bubble point, diffusion/pressure-hold), bacterial challenge testing, membrane chemistries, fouling and flux behavior, and compatibility with formulations and sterilization methods. These MCQs emphasize deeper understanding needed for scale-up and technology transfer, helping students prepare for exams and for designing robust filter qualification strategies in industry.
Q1. Which membrane pore size is most commonly accepted as “sterilizing-grade” for removal of bacteria from aqueous pharmaceutical solutions?
- 0.45 micrometer
- 0.22 micrometer
- 0.8 micrometer
- 1.2 micrometer
Correct Answer: 0.22 micrometer
Q2. Which organism is most frequently used as the bacterial challenge for sterilizing-grade membrane retention testing?
- Staphylococcus aureus
- Escherichia coli
- Brevundimonas (Pseudomonas) diminuta
- Bacillus subtilis
Correct Answer: Brevundimonas (Pseudomonas) diminuta
Q3. What is the primary purpose of performing an integrity test (e.g., bubble point) on a sterilizing filter before and after filtration?
- To measure filter flow rate under process conditions
- To determine the membrane’s chemical compatibility
- To verify the continuous absence of defects and pore wetting ensuring retention capability
- To quantify extractables from the filter material
Correct Answer: To verify the continuous absence of defects and pore wetting ensuring retention capability
Q4. Which of the following integrity tests is based on measuring gas flow through a wetted filter under a specified differential pressure over time?
- Bubble point test
- Diffusion or pressure-hold test
- Bacterial challenge test
- Visual pore inspection
Correct Answer: Diffusion or pressure-hold test
Q5. During filter qualification, what do the terms DQ, IQ, OQ and PQ stand for in the correct sequence?
- Design Qualification, Installation Qualification, Operational Qualification, Performance Qualification
- Design Quotation, Installation Quotation, Operational Quotation, Performance Quotation
- Device Qualification, Integration Qualification, Output Qualification, Process Qualification
- Design Qualification, Integration Qualification, Operational Qualification, Product Qualification
Correct Answer: Design Qualification, Installation Qualification, Operational Qualification, Performance Qualification
Q6. Which membrane material is often preferred for low-protein-binding filtration of aqueous drug products?
- Cellulose acetate (hydrophobic)
- PTFE (hydrophobic)
- Polyethersulfone (PES, hydrophilic grade)
- Polypropylene (non-membrane depth)
Correct Answer: Polyethersulfone (PES, hydrophilic grade)
Q7. For a sterile filtration process, what is the most appropriate approach to establish that a filter is suitable for a specific product containing surfactant?
- Assume all hydrophilic filters are compatible with surfactants
- Perform filter compatibility and retention testing with the actual product or a representative surrogate including integrity and bacterial challenge
- Use a smaller pore size to compensate for surfactant effects
- Only rely on manufacturer’s generic compatibility chart without empirical testing
Correct Answer: Perform filter compatibility and retention testing with the actual product or a representative surrogate including integrity and bacterial challenge
Q8. Which statement best describes the bubble point test result significance for a wetted membrane?
- It provides an exact pore size distribution across the entire filter
- It indicates pressure required to expel liquid from the largest continuous pore; a passing value demonstrates expected retention capacity
- It measures microbial count in filtrate directly
- It is useful only for gas filters and not for liquid filtration
Correct Answer: It indicates pressure required to expel liquid from the largest continuous pore; a passing value demonstrates expected retention capacity
Q9. What is a common cause of decreased permeate flux during sterile filtration of protein solutions at scale?
- Increased feed temperature improves viscosity excessively
- Use of hydrophilic membranes prevents any adsorption
- Sterilizing-grade filters always increase flux over time
Correct Answer: Formation of a fouling layer due to protein adsorption and concentration polarization
Q10. When scaling up a membrane filtration step, which parameter should be scaled first to maintain similar filtration performance?
- Filter cartridge color
- Shear rate at the membrane surface and transmembrane pressure (TMP) to reproduce similar flux/fouling behavior
- Length of tubing used only
- Time of day when filtration is performed
Correct Answer: Shear rate at the membrane surface and transmembrane pressure (TMP) to reproduce similar flux/fouling behavior
Q11. During qualification, what is the role of a bacterial challenge test for a sterilizing filter?
- To quantify extractables from the membrane
- To demonstrate the filter’s ability to retain a known population of bacteria under defined conditions
- To sterilize the filter by bacterial exposure
- To determine chemical compatibility with solvents
Correct Answer: To demonstrate the filter’s ability to retain a known population of bacteria under defined conditions
Q12. Which filter material is typically selected for filtration of organic solvents due to its intrinsic hydrophobicity?
- Hydrophilic PES
- Hydrophobic PTFE
- Regenerated cellulose
- Hydrophilic nylon
Correct Answer: Hydrophobic PTFE
Q13. What is the primary regulatory expectation regarding membrane filter qualification documentation during technology transfer?
- Only keep verbal records to remain flexible
- Comprehensive documented evidence that filter selection, installation, validation, and routine integrity testing demonstrate reproducible performance for the product at the target scale
- No documentation is required if supplier certifies the filter
- Submit only a certificate of analysis for each filter cartridge
Correct Answer: Comprehensive documented evidence that filter selection, installation, validation, and routine integrity testing demonstrate reproducible performance for the product at the target scale
Q14. Why is preconditioning or flushing of a filter with product or surrogate often performed before a bacterial retention test?
- To intentionally block pores and reduce retention
- To mimic process fouling and to reach steady-state membrane behavior representative of actual use
- Because integrity tests cannot be performed on dry filters
- Only to clean the filter for aesthetic reasons
Correct Answer: To mimic process fouling and to reach steady-state membrane behavior representative of actual use
Q15. Which performance metric expresses the reduction of microorganisms by filtration in logarithmic terms?
- Percent reduction
- Log Reduction Value (LRV)
- Transmembrane pressure (TMP)
- Flux units (L/m2·h)
Correct Answer: Log Reduction Value (LRV)
Q16. Which of the following is a correct rationale for performing both pre-use and post-use integrity testing of sterile filters?
- To compare filter weight before and after use
- To confirm that the filter had no defects before use and remained intact after processing, ensuring no breach occurred during filtration
- Because post-use integrity always fails and requires replacement
- To ensure the filter has maximum extractables after use
Correct Answer: To confirm that the filter had no defects before use and remained intact after processing, ensuring no breach occurred during filtration
Q17. Which situation is most likely to cause a false-positive result in a bubble point integrity test?
- Complete wetting of the membrane with the intended liquid
- Presence of residual air pockets or incomplete wetting leading to lower measured bubble point
- Using the correct wetting agent and procedure
- High-quality membrane with uniform pore size
Correct Answer: Presence of residual air pockets or incomplete wetting leading to lower measured bubble point
Q18. For a filter to be autoclaved in-line (in-situ) as part of sterilization, what must be demonstrated during qualification?
- That the autoclave reaches higher temperatures than specified
- That the filter assembly materials and seals tolerate autoclave cycles without loss of integrity, and post-autoclave integrity is confirmed
- That the filter will dissolve partially to improve flow
- That bubble point testing is unnecessary after autoclaving
Correct Answer: That the filter assembly materials and seals tolerate autoclave cycles without loss of integrity, and post-autoclave integrity is confirmed
Q19. When selecting a prefilter upstream of the sterilizing-grade filter, what is the primary objective?
- To increase the bacterial challenge on the final filter
- To remove particulate load and reduce fouling of the sterilizing-grade membrane, thereby improving throughput and filter lifetime
- To alter the chemical composition of the product
- To ensure only larger bacteria pass through to the final filter
Correct Answer: To remove particulate load and reduce fouling of the sterilizing-grade membrane, thereby improving throughput and filter lifetime
Q20. Which statement about endotoxin removal by typical 0.22 µm sterilizing-grade membrane filters is most accurate?
- All endotoxin is completely removed by 0.22 µm filters in every case
- Endotoxins (lipopolysaccharides) are small and may not be reliably removed by pore-size filtration; specific validation is required if endotoxin control is critical
- Endotoxin removal is irrelevant for parenteral products
- Using a larger pore size increases endotoxin removal efficiency
Correct Answer: Endotoxins (lipopolysaccharides) are small and may not be reliably removed by pore-size filtration; specific validation is required if endotoxin control is critical
