Qualification of Membrane Filter MCQs With Answer

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

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