Compatibility studies of herbs and excipients MCQs With Answer

Introduction

Compatibility studies between herbal actives and excipients are critical in herbal cosmetic formulation development. For M.Pharm students, understanding physicochemical and chemical interactions helps ensure product stability, safety and efficacy. This blog presents MCQs focused on analytical techniques (FTIR, DSC, TGA, XRD), chemical degradation pathways, excipient selection principles, pH and moisture effects, antioxidant and chelator roles, and strategies to mitigate incompatibilities. These questions are designed to deepen conceptual understanding and prepare students for practical formulation challenges, regulatory expectations, and research tasks in herbal cosmetics formulation and stability assessment.

Q1. Which analytical technique is most useful for detecting specific chemical interaction between a herbal extract functional group and an excipient by identifying shifts in vibrational frequencies?

• Differential Scanning Calorimetry (DSC)
• Fourier Transform Infrared Spectroscopy (FTIR)
• X-ray Diffraction (XRD)
• Thermogravimetric Analysis (TGA)

Correct Answer: Fourier Transform Infrared Spectroscopy (FTIR)

Q2. Which type of incompatibility commonly occurs when phenolic constituents of herbs oxidize in presence of metal ions leading to discoloration and loss of activity?

• Hydrolytic incompatibility
• Acid–base incompatibility
• Oxidative incompatibility
• Photolytic incompatibility

Correct Answer: Oxidative incompatibility

Q3. In compatibility screening, which thermal technique helps identify changes in melting point or formation of new crystalline phases between herb and excipient?

• UV-Visible Spectroscopy
• Differential Scanning Calorimetry (DSC)
• High-Performance Liquid Chromatography (HPLC)
• Gas Chromatography (GC)

Correct Answer: Differential Scanning Calorimetry (DSC)

Q4. When an herbal active is amorphous and an excipient induces recrystallization, which technique is most appropriate to monitor this change?

• Thermogravimetric Analysis (TGA)
• Fourier Transform Infrared Spectroscopy (FTIR)
• X-ray Diffraction (XRD)
• Colorimetry

Correct Answer: X-ray Diffraction (XRD)

Q5. Which excipient property is most critical to evaluate for moisture-sensitive herbal extracts to prevent hydrolytic degradation?

• Solubility in organic solvents
• Hygroscopicity and water activity
• pH buffering capacity in non-aqueous media
• Surface area of particles

Correct Answer: Hygroscopicity and water activity

Q6. A herbal polyphenol forms a complex with calcium in a cream base, reducing its bioavailability. Which interaction type best describes this?

• Hydrophobic interaction
• Metal chelation/complexation
• Van der Waals attraction
• Photodegradation

Correct Answer: Metal chelation/complexation

Q7. Which excipient is commonly used to protect herbal actives from oxidation in topical formulations?

• Peroxide-generating surfactants
• Antioxidants such as tocopherol or ascorbyl palmitate
• Strong oxidizing preservatives
• High concentration of metal salts

Correct Answer: Antioxidants such as tocopherol or ascorbyl palmitate

Q8. Forced degradation compatibility studies typically include which of the following stress conditions to reveal potential incompatibilities?

• Low humidity only
• Thermal, photolytic, oxidative and hydrolytic stress
• pH-neutral aqueous incubation exclusively
• Storage in inert atmosphere without stressors

Correct Answer: Thermal, photolytic, oxidative and hydrolytic stress

Q9. Which analytical approach is best to quantify a specific herbal marker compound after mixing with excipients during compatibility testing?

• Thermogravimetric Analysis (TGA)
• High-Performance Liquid Chromatography (HPLC)
• Polarimetry
• Refractive index measurement

Correct Answer: High-Performance Liquid Chromatography (HPLC)

Q10. When combining a herbal extract with a polymeric excipient for a controlled-release topical gel, which compatibility concern is most relevant?

• Polymer-induced enzymatic degradation of extract
• Phase separation, viscosity changes and potential binding to polymer reducing release
• Increased volatility of the herbal constituents
• Induction of microbial growth by polymer itself

Correct Answer: Phase separation, viscosity changes and potential binding to polymer reducing release

Q11. Which statement best describes the role of pH in herb–excipient compatibility for aqueous herbal lotions?

• pH only affects color but not chemical stability
• pH can alter ionization state, solubility and degradation rate of herbal constituents
• pH has no impact if preservatives are present
• Maintaining extreme pH is always beneficial for stability

Correct Answer: pH can alter ionization state, solubility and degradation rate of herbal constituents

Q12. Which excipient selection strategy can minimize interactions with tannin-rich herbal extracts used in cosmetics?

• Use of metal-containing colorants
• Avoid proteinaceous excipients and prefer inert, non-ionic polymers or silica
• Increase formulation pH to alkaline extremes
• Incorporate reducing sugar excipients to stabilize tannins

Correct Answer: Avoid proteinaceous excipients and prefer inert, non-ionic polymers or silica

Q13. In a binary mixture compatibility test, appearance of a new endotherm in DSC thermogram often indicates what?

• Complete miscibility with no interaction
• Formation of a new crystalline phase or interaction (e.g., complex or salt)
• Only moisture loss with no chemical change
• Instrumental artifact unrelated to sample

Correct Answer: Formation of a new crystalline phase or interaction (e.g., complex or salt)

Q14. Which preservative–herb incompatibility concern is most relevant for herbal extracts containing aldehydes or phenolic groups?

• Preservative enhancement of antioxidant activity
• Covalent reaction between preservatives (e.g., formaldehyde releasers) and active groups causing loss of potency
• Preservative lowering pH to stabilize aldehydes
• Increased solubility of phenolics without reactivity

Correct Answer: Covalent reaction between preservatives (e.g., formaldehyde releasers) and active groups causing loss of potency

Q15. Which technique is most suitable to monitor loss of volatile herbal essential oil components during compatibility or stability testing?

• Gas Chromatography (GC)
• Ultraviolet-visible spectroscopy
• Polarization microscopy
• X-ray Diffraction (XRD)

Correct Answer: Gas Chromatography (GC)

Q16. For reducing herb–excipient incompatibilities due to metal ions, which formulation approach is most appropriate?

• Add metal chelators or use metal-free grade excipients and containers
• Increase metal ion concentration to saturate binding
• Use iron-containing pigments for their stabilizing effect
• Avoid antioxidants to reduce chelation

Correct Answer: Add metal chelators or use metal-free grade excipients and containers

Q17. When a herbal extract shows mass loss upon heating in the 50–150°C range during TGA, what is the most likely explanation?

• Complete decomposition of the active constituent
• Evaporation of bound and unbound water and volatile components
• Formation of new crystalline phase
• Measurement error only

Correct Answer: Evaporation of bound and unbound water and volatile components

Q18. Which formulation technique can help mask unpleasant taste of herbal actives and reduce direct contact with incompatible sweetening excipients?

• Direct compression without coating
• Microencapsulation or coating of the herbal active
• Mixing with reactive excipients to alter flavor chemistry
• Heating the herb with sugar to caramelize taste

Correct Answer: Microencapsulation or coating of the herbal active

Q19. In accelerated compatibility studies for herbal cosmetics, which packaging factor must be simulated to detect package–product interactions?

• Exposure to inert gas only
• Interaction with packaging materials (adsorption, leachables) and headspace composition
• Only color of the package without material contact
• Packaging weight changes solely

Correct Answer: Interaction with packaging materials (adsorption, leachables) and headspace composition

Q20. Why is it important to use standardized marker compounds and reference standards during herb–excipient compatibility testing?

• Standardization is unnecessary if qualitative tests are performed
• Reference standards allow quantitative assessment of degradation, ensure specificity and reproducibility of analytical methods
• Standards increase cost without improving data quality
• Marker compounds mask incompatibilities in real extracts

Correct Answer: Reference standards allow quantitative assessment of degradation, ensure specificity and reproducibility of analytical methods

Download