Formulation and preparation of hair dyes MCQs With Answer is an essential review for B.Pharm students focusing on cosmetic pharmacology, formulation science, and safety assessment. This concise guide covers dye chemistry, types of hair dyes (temporary, semi-permanent, permanent, oxidative), key ingredients such as dye intermediates, couplers, oxidizing agents, alkalizers, solvents, surfactants, and preservatives, as well as formulation strategies, stability testing, analytical methods, and regulatory considerations. Emphasis is placed on mechanism of color development, interactions with hair keratin, allergenicity, and quality control tests like pH, viscosity, peroxide assay, and spectrophotometry. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which class of hair dyes requires hydrogen peroxide and aromatic amine intermediates to develop permanent color?
- Temporary dyes
- Semi-permanent dyes
- Oxidative (permanent) dyes
- Direct dyes
Correct Answer: Oxidative (permanent) dyes
Q2. What is the primary function of alkalizing agents (e.g., ammonia) in oxidative hair dye formulations?
- Act as preservatives
- Open the hair cuticle to allow dye penetration
- Stabilize hydrogen peroxide
- Reduce dye development time
Correct Answer: Open the hair cuticle to allow dye penetration
Q3. Which ingredient is commonly used as an oxidizing agent in permanent hair dye systems?
- Ammonia
- Polyethylene glycol
- Hydrogen peroxide
- Sodium lauryl sulfate
Correct Answer: Hydrogen peroxide
Q4. Couplers in oxidative hair dye chemistry primarily influence which aspect of the final color?
- Fragrance intensity
- Shade hue and chroma
- Viscosity of the formulation
- Peroxide stability
Correct Answer: Shade hue and chroma
Q5. Which hair dye intermediate is associated with higher risk of allergic contact dermatitis and is regulated in many regions?
- p-Phenylenediamine (PPD)
- Resorcinol
- Toluene
- Phenoxyethanol
Correct Answer: p-Phenylenediamine (PPD)
Q6. In formulation design, what is the role of surfactants in hair dye creams?
- Act as oxidizing agents
- Enhance wetting and emulsification for uniform application
- Provide color development
- Neutralize peroxide
Correct Answer: Enhance wetting and emulsification for uniform application
Q7. Which analytical method is most suitable for quantifying dye intermediates and couplers in formulations?
- TLC only
- UV-visible spectrophotometry only
- HPLC (High-performance liquid chromatography)
- pH meter
Correct Answer: HPLC (High-performance liquid chromatography)
Q8. What is the primary mechanism by which permanent oxidative dyes bind color to the hair fiber?
- Surface adsorption without penetration
- Covalent bonding within melanin granules
- In-situ formation of large dye molecules inside the hair cortex
- Electrostatic interaction with cuticle lipids
Correct Answer: In-situ formation of large dye molecules inside the hair cortex
Q9. Which formulation parameter must be controlled to prevent premature decomposition of hydrogen peroxide in hair dye products?
- pH and presence of catalytic metals
- Fragrance type
- Amount of dye intermediate only
- Packaging color
Correct Answer: pH and presence of catalytic metals
Q10. Direct dyes (non-oxidative) differ from oxidative dyes because they:
- Require an oxidant to develop color
- Form color molecules inside the cortex
- Directly deposit preformed color on hair without oxidation
- Always provide permanent color
Correct Answer: Directly deposit preformed color on hair without oxidation
Q11. Which excipient is commonly used as a viscosity enhancer in cream hair dye formulations?
- Sodium chloride
- Carbomer
- Hydrogen peroxide
- p-Phenylenediamine
Correct Answer: Carbomer
Q12. What stability test assesses color change over time under accelerated conditions?
- Patch test
- Accelerated aging (storage at elevated temperature and light)
- Peroxide titration only
- Viscosity measurement at room temperature
Correct Answer: Accelerated aging (storage at elevated temperature and light)
Q13. In permanent dye formulation, which component acts as a primary dye intermediate commonly oxidized to form colored species?
- Isopropyl alcohol
- p-Phenylenediamine (PPD)
- Sodium lauryl sulfate
- Glycerin
Correct Answer: p-Phenylenediamine (PPD)
Q14. Which regulatory consideration is most important for hair dye products intended for the scalp?
- Vehicle viscosity only
- Allergen labelling and banned substance compliance
- Choice of perfume only
- Container color
Correct Answer: Allergen labelling and banned substance compliance
Q15. What is the purpose of adding antioxidants (e.g., sodium sulfite) to hair dye formulations?
- To accelerate peroxide action
- To prevent premature oxidation of dye intermediates
- To raise formulation pH
- To act as primary colorants
Correct Answer: To prevent premature oxidation of dye intermediates
Q16. Which test detects potential immediate allergic reactions before full application of hair dye?
- Patch test (skin sensitivity test)
- pH test
- Peroxide assay
- Color fastness wash test
Correct Answer: Patch test (skin sensitivity test)
Q17. Henna is classified as which type of hair colorant?
- Oxidative permanent dye
- Synthetic direct dye
- Natural pigment/direct dye
- Coupler agent
Correct Answer: Natural pigment/direct dye
Q18. Which parameter is critical to adjust to control the rate of oxidation in hair dye reactions?
- pH of formulation
- Packaging size
- Amount of fragrance
- Label font size
Correct Answer: pH of formulation
Q19. What is the role of chelating agents (e.g., EDTA) in hair dye formulations?
- Enhance color formation by supplying metal ions
- Bind trace metals to prevent catalytic decomposition of peroxide
- Act as primary dye intermediates
- Reduce formulation viscosity
Correct Answer: Bind trace metals to prevent catalytic decomposition of peroxide
Q20. Which safety test is used to evaluate eye irritation potential of cosmetic hair products?
- Dermal sensitization only
- Ocular irritation test or validated in vitro alternatives
- Peroxide concentration assay
- Colorimetric shade test
Correct Answer: Ocular irritation test or validated in vitro alternatives
Q21. In hair dye formulations, surfactant choice can influence which of the following?
- Cuticle opening, rinsing behavior, and foam
- Color chemistry only
- Peroxide molecular weight
- Melanin synthesis
Correct Answer: Cuticle opening, rinsing behavior, and foam
Q22. What analytical parameter is commonly used to evaluate color depth and shade reproducibility?
- Viscosity at shear
- Colorimetric measurement (CIELAB or spectrophotometry)
- pH alone
- Peroxide titration only
Correct Answer: Colorimetric measurement (CIELAB or spectrophotometry)
Q23. Which preservative concern must formulators consider in hair dye products that are mixed with peroxide just before use?
- Peroxide will enhance preservative efficiency
- Preservatives may be inactivated by oxidants and require selection accordingly
- No preservative is required
- Preservatives change color hue
Correct Answer: Preservatives may be inactivated by oxidants and require selection accordingly
Q24. Which structural feature of hair allows penetration of low molecular weight dye intermediates into the cortex?
- Hydrophobic sebum on the surface
- Keratin matrix with microfibrillar gaps when cuticle is opened
- Melanin granule impermeability
- Rigid lipid bilayer
Correct Answer: Keratin matrix with microfibrillar gaps when cuticle is opened
Q25. Which of the following is a measure used to determine residual peroxide in a mixed hair dye system?
- pH strip comparison
- Peroxide titration (iodometric method)
- Viscosity measurement
- HPLC for PPD only
Correct Answer: Peroxide titration (iodometric method)
Q26. Why are fragrance and essential oils carefully selected in hair dye formulas?
- They act as primary colorants
- They may interact with oxidants or increase sensitization risk
- They stabilize hydrogen peroxide
- They always reduce pH
Correct Answer: They may interact with oxidants or increase sensitization risk
Q27. What is the purpose of including humectants (e.g., glycerin) in hair dye formulations?
- To promote oxidative coupling reactions
- To retain moisture and improve handling and spreadability
- To increase peroxide concentration
- To act as couplers for color formation
Correct Answer: To retain moisture and improve handling and spreadability
Q28. Which environmental or regulatory concern is associated with certain synthetic hair dyes?
- Biodegradability and restricted aromatic amines due to toxicity
- Excessive foam formation in wastewater
- High melting point of dye intermediates
- Lack of color variety
Correct Answer: Biodegradability and restricted aromatic amines due to toxicity
Q29. For B.Pharm students, understanding the kinetics of dye formation is important because it helps predict:
- The final packaging design only
- Rate of color development, required contact time, and shade reproducibility
- Fragrance volatility
- Theoretical melting point of dyes
Correct Answer: Rate of color development, required contact time, and shade reproducibility
Q30. Which quality control parameter ensures batch-to-batch uniformity of a hair dye product?
- Random label design changes
- Specification of raw material identity, assay, pH, viscosity, and colorimetric profile
- Changing perfume to match trends
- Ad hoc mixing times without records
Correct Answer: Specification of raw material identity, assay, pH, viscosity, and colorimetric profile
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