SFC pharmaceutical applications MCQs With Answer

Introduction: SFC pharmaceutical applications MCQs With Answer is a focused question set tailored for M.Pharm students studying Advanced Instrumental Analysis (MPA 201T). Supercritical fluid chromatography (SFC) is increasingly used in pharmaceutical analysis for fast separations, chiral separations, and greener sample processing using CO2-based mobile phases. This quiz collection covers fundamentals, instrumentation, method development, detectors, preparative scale-up, troubleshooting and regulatory considerations. Each question is designed to deepen conceptual understanding and support practical skills required in formulation, impurity profiling, and enantiomeric purity assessment. Use these MCQs for self-assessment, classroom review, and exam preparation to consolidate both theory and application of SFC in pharmaceutical contexts.

Q1. What is the primary mobile phase in analytical supercritical fluid chromatography (SFC) commonly used for pharmaceutical separations?

• Hexane
• Supercritical carbon dioxide (CO2)
• Water
• Methanol only

Correct Answer: Supercritical carbon dioxide (CO2)

Q2. Which statement best explains why modifiers such as methanol or acetonitrile are added to supercritical CO2 in SFC?

• Modifiers increase the viscosity of the mobile phase to improve column pressure
• Modifiers change the polarity and solvating power to improve solubility and elution of polar analytes
• Modifiers convert CO2 into a liquid at room temperature
• Modifiers prevent the use of detectors like MS

Correct Answer: Modifiers change the polarity and solvating power to improve solubility and elution of polar analytes

Q3. In SFC method development for chiral separations, which stationary phase type is most commonly employed?

• C18 reversed-phase
• Polysaccharide-based chiral stationary phases (e.g., cellulose or amylose derivatives)
• Ion-exchange resins
• Size-exclusion polymer columns

Correct Answer: Polysaccharide-based chiral stationary phases (e.g., cellulose or amylose derivatives)

Q4. Which detector is most compatible and widely used for SFC coupled with high-sensitivity structural identification in pharmaceutical analysis?

• Refractive index (RI) detector
• Mass spectrometry (MS)
• Conductivity detector
• Thermal conductivity detector

Correct Answer: Mass spectrometry (MS)

Q5. What is the function of the backpressure regulator (BPR) in an SFC system?

• To cool the column oven
• To maintain the mobile phase in a supercritical (or controlled dense gas) state by controlling system pressure
• To inject sample automatically
• To act as a detector

Correct Answer: To maintain the mobile phase in a supercritical (or controlled dense gas) state by controlling system pressure

Q6. Which condition increase generally leads to decreased retention of analytes in CO2-based SFC if analyte solubility in the mobile phase increases?

• Decrease in modifier percentage
• Increase in modifier percentage (e.g., more methanol)
• Lower column temperature only
• Use of a less polar stationary phase

Correct Answer: Increase in modifier percentage (e.g., more methanol)

Q7. For preparative SFC scale-up from analytical to preparative column, which parameter is most critical to maintain equivalence in separation?

• Maintaining the same solvent gradient time irrespective of column size
• Scaling linear velocity and gradient composition while accounting for column diameter and particle size
• Using the same injection volume per run as analytical scale
• Always increasing temperature by 20°C for preparative columns

Correct Answer: Scaling linear velocity and gradient composition while accounting for column diameter and particle size

Q8. In SFC-MS method optimization for basic pharmaceutical compounds, which additive is commonly used in the modifier to improve peak shape and MS response?

• Formic acid or ammonium formate
• Sodium chloride
• EDTA
• Hydrochloric acid at high concentration

Correct Answer: Formic acid or ammonium formate

Q9. Which retention mechanism is primarily exploited in normal-phase-like SFC separations using CO2 with polar modifiers?

• Hydrophobic reversed-phase partitioning only
• Partitioning combined with specific polar interactions (hydrogen bonding, dipole, π-π interactions) with the stationary phase
• Size exclusion based on molecular weight
• Ion exchange between stationary phase and analyte

Correct Answer: Partitioning combined with specific polar interactions (hydrogen bonding, dipole, π-π interactions) with the stationary phase

Q10. Which of the following is an advantage of SFC over traditional HPLC for certain pharmaceutical applications?

• Higher organic solvent consumption leading to higher cost
• Faster run times and reduced solvent waste due to CO2-based mobile phase
• Inability to separate chiral compounds
• Less compatibility with MS detectors

Correct Answer: Faster run times and reduced solvent waste due to CO2-based mobile phase

Q11. When analyzing thermolabile drug impurities, why might SFC be preferred to GC?

• SFC requires much higher temperatures than GC
• SFC uses a supercritical mobile phase at moderate temperatures, reducing thermal degradation risk compared to GC
• SFC cannot separate small volatile compounds
• SFC is always slower than GC, reducing sample throughput

Correct Answer: SFC uses a supercritical mobile phase at moderate temperatures, reducing thermal degradation risk compared to GC

Q12. What is a common cause of peak tailing for basic analytes in SFC and a typical remedy?

• Excess modifier causing overloading; remedy is reduce modifier percentage
• Interaction with residual silanols on silica-based stationary phases; remedy is add basic additives (e.g., diethylamine) or use end-capped columns
• Low inlet temperature; remedy is raise temperature by 50°C
• Detector mismatch; remedy is change to RID detector

Correct Answer: Interaction with residual silanols on silica-based stationary phases; remedy is add basic additives (e.g., diethylamine) or use end-capped columns

Q13. Which parameter should be closely monitored when coupling SFC to a mass spectrometer to ensure stable ionization?

• Column particle size only
• Make-up solvent composition and flow to support electrospray ionization (ESI)
• Injector syringe diameter
• Only the detector temperature

Correct Answer: Make-up solvent composition and flow to support electrospray ionization (ESI)

Q14. In SFC, what is the effect of increasing system backpressure while keeping temperature constant?

• Decrease mobile phase density and decrease elution strength
• Increase mobile phase density and often increase solvation strength, potentially decreasing retention
• No effect on mobile phase properties
• Always causes precipitation of analytes in the column

Correct Answer: Increase mobile phase density and often increase solvation strength, potentially decreasing retention

Q15. For enantiomeric purity determination using SFC, which mobile phase strategy often improves chiral recognition on polysaccharide columns?

• Using 100% CO2 without any modifier
• Adding a small percentage of alcohol modifier with specific additives (acids or bases) tailored to analyte to enhance interactions
• Switching to aqueous buffer only
• Using strong ion-pairing reagents in high concentration

Correct Answer: Adding a small percentage of alcohol modifier with specific additives (acids or bases) tailored to analyte to enhance interactions

Q16. Which safety consideration is important when handling supercritical CO2 systems in the pharmaceutical lab?

• No special training required because CO2 is inert and harmless
• Ensure proper ventilation, pressure relief devices, and training for handling high-pressure cylinders and potential rapid depressurization
• Only temperature control is required; pressure is irrelevant
• CO2 poses a severe flammability risk and requires explosion-proof equipment

Correct Answer: Ensure proper ventilation, pressure relief devices, and training for handling high-pressure cylinders and potential rapid depressurization

Q17. Which analytical challenge is specifically addressed by using SFC for lipophilicity (log P) related separations in drug discovery?

• Inability to separate nonpolar compounds
• Improved separation of medium-to-high lipophilicity compounds with shorter equilibration times and reduced organic waste compared to HPLC
• Only suitable for inorganic impurities
• Elimination of the need for detectors in log P assessment

Correct Answer: Improved separation of medium-to-high lipophilicity compounds with shorter equilibration times and reduced organic waste compared to HPLC

Q18. During method transfer from HPLC to SFC for a pharmaceutical impurity profile, which factor often requires particular attention?

• Switching to SFC always removes the need to validate the method
• Differences in selectivity and detector response, requiring re-optimization of gradient, modifier, and possibly detector settings
• Only column length matters; everything else stays identical
• SFC cannot detect impurities below 1% level

Correct Answer: Differences in selectivity and detector response, requiring re-optimization of gradient, modifier, and possibly detector settings

Q19. Which additive is commonly used in the modifier to improve the ionization of weakly acidic analytes in SFC-MS?

• Trifluoroacetic acid (TFA) at high concentration, without considering MS suppression
• Low concentration ammonium acetate or ammonium formate to buffer and enhance deprotonation in negative mode
• Saturated sodium hydroxide
• Large amounts of EDTA

Correct Answer: Low concentration ammonium acetate or ammonium formate to buffer and enhance deprotonation in negative mode

Q20. Which validation parameter is particularly critical to demonstrate when adopting SFC for quantitative impurity analysis in regulatory submissions?

• Only visual inspection of chromatograms is sufficient
• Specificity/selectivity for impurities and degradation products, along with accuracy, precision, linearity, LOD/LOQ under SFC conditions
• Validation is unnecessary if HPLC was previously validated
• Only the column brand needs to be validated

Correct Answer: Specificity/selectivity for impurities and degradation products, along with accuracy, precision, linearity, LOD/LOQ under SFC conditions

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