Pharmaceutical applications of HPTLC MCQs With Answer

Introduction

Pharmaceutical applications of HPTLC MCQs With Answer is a focused question bank designed for M.Pharm students studying Advanced Instrumental Analysis (MPA 201T). High-Performance Thin-Layer Chromatography (HPTLC) remains a versatile, high-throughput chromatographic tool in pharmaceutical analysis for assay, impurity profiling, herbal fingerprinting, stability testing and method validation. This blog provides 20 carefully crafted multiple-choice questions emphasizing practical aspects — plate chemistry, sample application, development, detection modes, quantitation, validation and hyphenated techniques such as HPTLC-MS. Each question includes four options and the correct answer, helping students strengthen conceptual understanding and prepare for exams and practical method development in pharmaceutical laboratories.

Q1. Which statement best describes the fundamental principle of HPTLC?

• Capillary electrophoresis with laser-induced fluorescence detection
• Adsorption-based planar chromatography using high-resolution precoated plates with instrumental sample application and densitometric scanning
• Gas-phase separation on packed columns followed by thermal conductivity detection
• Ion-exchange chromatography on resin beads in a planar format

Correct Answer: Adsorption-based planar chromatography using high-resolution precoated plates with instrumental sample application and densitometric scanning

Q2. Which stationary phase is most commonly used in pharmaceutical HPTLC for general non-polar to moderately polar drugs?

• Silica gel 60 F254
• Carboxymethyl cellulose
• Polystyrene-divinylbenzene
• Anion-exchange cellulose

Correct Answer: Silica gel 60 F254

Q3. In HPTLC, what is the main purpose of using a pre-saturated development chamber?

• To increase the plate surface roughness
• To ensure reproducible mobile phase vapor atmosphere and reduce edge effects during development
• To dry the sample spots faster before scanning
• To adsorb impurities from the mobile phase

Correct Answer: To ensure reproducible mobile phase vapor atmosphere and reduce edge effects during development

Q4. Which of the following is a primary advantage of HPTLC over classical TLC for pharmaceutical analysis?

• Lower solvent consumption per sample by an order of magnitude
• Ability to analyze volatile compounds only
• Automated precise sample application, better resolution and densitometric quantitation for many samples in parallel
• Exclusive compatibility with GC-MS detectors

Correct Answer: Automated precise sample application, better resolution and densitometric quantitation for many samples in parallel

Q5. In densitometric quantitation on HPTLC, which parameter is directly used to construct calibration curves?

• Retention factor (Rf) value
• Peak/spot area or peak height measured by the scanner
• Mobile phase vapor pressure
• Plate thickness

Correct Answer: Peak/spot area or peak height measured by the scanner

Q6. Which derivatization approach is most suitable in HPTLC for making non-UV absorbing drugs visible under UV light?

• Use of iodine vapor only
• Chemical derivatization with a chromogenic reagent (e.g., anisaldehyde or ninhydrin) followed by heating if required
• Increasing mobile phase polarity to elute compounds as colorless bands
• Applying mass spectrometry directly without derivatization

Correct Answer: Chemical derivatization with a chromogenic reagent (e.g., anisaldehyde or ninhydrin) followed by heating if required

Q7. Which hyphenated technique allows molecular identification of HPTLC-separated zones with minimal sample disturbance?

• HPTLC-UV only
• HPTLC-MS interface coupling (e.g., TLC-MS direct elution)
• HPTLC-electrochemical detection without elution
• HPTLC-FTIR imaging without spot extraction

Correct Answer: HPTLC-MS interface coupling (e.g., TLC-MS direct elution)

Q8. Which parameter describes the relative migration distance of a compound on an HPTLC plate?

• Retention index (RI)
• Retention factor (Rf)
• Capacity factor (k’)
• Van Deemter coefficient

Correct Answer: Retention factor (Rf)

Q9. For method validation of an HPTLC assay according to ICH, which of the following is routinely assessed?

• Only system suitability
• Specificity, linearity, accuracy, precision, LOD/LOQ, robustness and range
• Only response time of the detector
• Only mobile phase boiling point

Correct Answer: Specificity, linearity, accuracy, precision, LOD/LOQ, robustness and range

Q10. In HPTLC impurity profiling of a drug substance, which approach best improves detection of low-level degradants?

• Applying very large spot volumes to increase spot diameter
• Using selective derivatization, optimized mobile phase and densitometric scanning at specific wavelengths or hyphenation to MS
• Using uncoated glass plates
• Shortening development distance to less than 1 cm

Correct Answer: Using selective derivatization, optimized mobile phase and densitometric scanning at specific wavelengths or hyphenation to MS

Q11. Which plate treatment improves reproducibility by removing adsorbed water and organic contaminants before sample application?

• Prewashing the plate with mobile phase and activating at elevated temperature (e.g., 110–120 °C)
• Spraying with olive oil
• Storing plates in a humid chamber overnight
• Coating with wax

Correct Answer: Prewashing the plate with mobile phase and activating at elevated temperature (e.g., 110–120 °C)

Q12. In HPTLC, what is the effect of increasing the length of applied sample bands (longer band) while keeping the same sample mass?

• Increase in lateral diffusion leading to worse resolution between closely eluting zones
• Decrease in spot area on the plate
• No effect on peak shape or resolution
• Complete retention at origin

Correct Answer: Increase in lateral diffusion leading to worse resolution between closely eluting zones

Q13. Which detection mode is particularly useful in HPTLC to detect antioxidant compounds directly on the plate?

• DPPH bioautography or spraying with DPPH radical solution to visualize antioxidant activity as bleaching zones
• Only white light illumination
• Use of iodine vapor for all antioxidants specifically
• Electrochemical staining with silver nitrate exclusively

Correct Answer: DPPH bioautography or spraying with DPPH radical solution to visualize antioxidant activity as bleaching zones

Q14. When developing an HPTLC method for a polarity range of herbal constituents, which mobile phase strategy is advisable?

• Use a single very non-polar solvent for all compounds
• Employ gradient or stepwise solvent systems and multiple plate developments or dual-mode separations to cover wide polarity range
• Only use water as mobile phase
• Develop without saturation to speed analysis

Correct Answer: Employ gradient or stepwise solvent systems and multiple plate developments or dual-mode separations to cover wide polarity range

Q15. Which factor most directly influences sensitivity (LOD) in densitometric HPTLC analysis?

• Thickness of the glass plate only
• Detector wavelength selection, derivatization to enhance absorbance/fluorescence, and sample application precision
• Color of the laboratory walls
• Operator height

Correct Answer: Detector wavelength selection, derivatization to enhance absorbance/fluorescence, and sample application precision

Q16. For stability-indicating HPTLC methods, which practice is essential during forced degradation studies?

• Only analyze the intact drug without exposing to stress conditions
• Subject the drug to acid/base hydrolysis, oxidation, heat, light and humidity and demonstrate resolution between drug and degradation products
• Use only neutral aqueous conditions for all tests
• Perform degradation at -20 °C

Correct Answer: Subject the drug to acid/base hydrolysis, oxidation, heat, light and humidity and demonstrate resolution between drug and degradation products

Q17. In HPTLC fingerprinting of herbal extracts, which objective is most relevant for quality control?

• Quantifying only one major compound irrespective of the rest of the profile
• Providing a reproducible multicomponent pattern that allows authentication, batch-to-batch comparison and detection of adulteration
• Measuring only pH of the extract
• Ensuring all bands have identical Rf values across unrelated species

Correct Answer: Providing a reproducible multicomponent pattern that allows authentication, batch-to-batch comparison and detection of adulteration

Q18. Which of the following statements about HPTLC-MS coupling is correct?

• HPTLC-MS coupling is impossible because planar plates cannot interface with mass spectrometers
• Direct elution or TLC-MS interfaces allow extraction of separated zones from the plate into MS for structural identification and confirmation
• MS detection on plates requires radioisotopes only
• HPTLC-MS provides only UV spectra, not mass spectra

Correct Answer: Direct elution or TLC-MS interfaces allow extraction of separated zones from the plate into MS for structural identification and confirmation

Q19. Which system suitability criteria is commonly evaluated for HPTLC before accepting a run?

• Spot symmetry or tailing factor, resolution between critical pairs, reproducibility of Rf and signal relative standard deviation
• Color of the mobile phase only
• Plate thickness measured in micrometers in each corner
• Operator’s subjective impression of band beauty

Correct Answer: Spot symmetry or tailing factor, resolution between critical pairs, reproducibility of Rf and signal relative standard deviation

Q20. How can HPTLC be used for dissolution testing in a pharmaceutical QC environment?

• It cannot be used for dissolution testing under any circumstances
• Aliquots from dissolution media can be applied directly to HPTLC plates, separated and quantified to determine drug release profiles with simultaneous multi-sample analysis
• Only the dissolution medium color can be measured visually
• Dissolution must always be analyzed by visual turbidity assessment only

Correct Answer: Aliquots from dissolution media can be applied directly to HPTLC plates, separated and quantified to determine drug release profiles with simultaneous multi-sample analysis

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