Preservatives used in herbal cosmetics MCQs With Answer

Introduction: This quiz collection on “Preservatives used in herbal cosmetics” is designed for M.Pharm students studying Herbal Cosmetics (MPG 204T). It focuses on selection criteria, mechanisms of action, compatibility with botanical actives, regulatory constraints, and practical aspects such as pH-dependence, preservative efficacy testing and synergists. Questions cover commonly used synthetic and natural preservatives, safety and sensitization issues, and formulation strategies to maintain microbiological stability of herbal products. These MCQs will help you deepen understanding beyond basic definitions, preparing you for exams and formulation challenges encountered when designing safe, effective herbal cosmetic preparations.

Q1. What is the primary function of a preservative in herbal cosmetic formulations?

• To inhibit microbial growth and prolong product shelf-life
• To act as a fragrance enhancer
• To increase viscosity of emulsions
• To provide UV protection

Correct Answer: To inhibit microbial growth and prolong product shelf-life

Q2. Which of the following is a commonly used paraben in cosmetics?

• Methylparaben
• Propyl gallate
• Butylated hydroxyanisole (BHA)
• Benzyl alcohol

Correct Answer: Methylparaben

Q3. Which preservative is known for good activity across a broad pH range (approximately pH 3–10) and is widely used in modern formulations?

• Phenoxyethanol
• Sorbic acid
• Benzoic acid
• Propionic acid

Correct Answer: Phenoxyethanol

Q4. Which preservative is a cationic quaternary ammonium compound and is incompatible with anionic surfactants?

• Benzalkonium chloride
• Phenoxyethanol
• Sodium benzoate
• Propylparaben

Correct Answer: Benzalkonium chloride

Q5. Which essential oil is frequently cited for its antimicrobial properties and is sometimes used as a complementary natural preservative in herbal cosmetics?

• Tea tree oil (Melaleuca alternifolia)
• Sandalwood oil
• Olive oil
• Coconut oil

Correct Answer: Tea tree oil (Melaleuca alternifolia)

Q6. Which of the following is a formaldehyde-releasing preservative?

• DMDM hydantoin
• Methylparaben
• Benzoic acid
• Phenoxyethanol

Correct Answer: DMDM hydantoin

Q7. What is the standardized microbiological test commonly used to evaluate preservative effectiveness in cosmetics?

• USP <51> Antimicrobial Effectiveness Test (Preservative Efficacy Test)
• pH stability test
• Viscosity stability test
• Organoleptic assessment

Correct Answer: USP <51> Antimicrobial Effectiveness Test (Preservative Efficacy Test)

Q8. Sodium benzoate (benzoic acid) is most effective as a preservative at which pH range?

• Below pH 4.5
• pH 6.0–8.0
• pH 8.0–10.0
• Any pH

Correct Answer: Below pH 4.5

Q9. What is the primary role of EDTA (ethylenediaminetetraacetic acid) when used alongside preservatives?

• Acts as a chelating agent to bind divalent metal ions improving preservative efficacy
• Functions as a humectant
• Serves as an emulsifier
• Acts as a primary antimicrobial preservative

Correct Answer: Acts as a chelating agent to bind divalent metal ions improving preservative efficacy

Q10. Which preservative has been restricted/banned in many regions for use in leave-on cosmetics due to contact sensitization concerns?

• Methylisothiazolinone (MI)
• Phenoxyethanol
• Methylparaben
• Benzoic acid

Correct Answer: Methylisothiazolinone (MI)

Q11. Which preservative is particularly effective against fungi (antifungal) but relatively less potent against bacteria?

• Sorbic acid (sorbates)
• Parabens
• Phenoxyethanol
• Benzyl alcohol

Correct Answer: Sorbic acid (sorbates)

Q12. Which aromatic alcohol is commonly used at concentrations up to about 1% as a preservative and solvent in cosmetics?

• Benzyl alcohol
• Benzoic acid
• Diazolidinyl urea
• Triclosan

Correct Answer: Benzyl alcohol

Q13. What is the primary antimicrobial mechanism of quaternary ammonium compounds like benzalkonium chloride?

• Disruption of microbial cell membranes leading to leakage of cellular contents
• Inhibition of cell wall synthesis
• Intercalation into microbial DNA
• Chelation of essential metal ions

Correct Answer: Disruption of microbial cell membranes leading to leakage of cellular contents

Q14. Which formulation factor in herbal cosmetics most commonly reduces the effectiveness of a preservative system?

• High content of plant extracts/organic load that consumes preservative activity
• Presence of EDTA
• Low water activity (very dry)
• Use of inert packaging

Correct Answer: High content of plant extracts/organic load that consumes preservative activity

Q15. Which metabolic process present in some herbal extracts can degrade ester-based preservatives like parabens?

• Hydrolysis by esterases
• Photolysis by visible light
• Oxidative decarboxylation
• Polymerization

Correct Answer: Hydrolysis by esterases

Q16. Which preservative is commonly accepted in many natural/organic certification standards (e.g., COSMOS) and often used in herbal cosmetics?

• Sodium benzoate
• Methylparaben
• Phenoxyethanol
• Methylisothiazolinone

Correct Answer: Sodium benzoate

Q17. Which analytical technique is commonly used to quantify residual preservative concentration in finished herbal cosmetic products during stability studies?

• High-performance liquid chromatography (HPLC)
• Preservative efficacy test (PET) plate count
• pH meter reading
• Microscopy

Correct Answer: High-performance liquid chromatography (HPLC)

Q18. Which preservative class releases formaldehyde slowly and is used to provide long-lasting preservation?

• Formaldehyde releasers such as diazolidinyl urea
• Parabens
• Sorbates
• Phenoxyethanol

Correct Answer: Formaldehyde releasers such as diazolidinyl urea

Q19. Which preservative is regarded as relatively stable and effective across slightly alkaline to neutral pH ranges and is widely used in modern formulations?

• Phenoxyethanol
• Benzoic acid
• Sorbic acid
• Benzyl alcohol

Correct Answer: Phenoxyethanol

Q20. Which antimicrobial agent has been restricted in many personal care products due to concerns about endocrine disruption and environmental persistence?

• Triclosan
• Phenoxyethanol
• Parabens
• Benzyl alcohol

Correct Answer: Triclosan

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