Reichert–Meissl (RM) value MCQs With Answer

Reichert–Meissl (RM) value MCQs With Answer

The Reichert–Meissl (RM) value is a key quality test in pharmaceutical and food analysis, especially for B. Pharm students learning fat and oil assessment. This concise introduction explains that the RM value measures volatile short‑chain fatty acids liberated by saponification, distilled into a boric acid solution and titrated with standardized alkali. Understanding RM helps detect adulteration of dairy fats (butter, ghee) and evaluate fat purity, sample preparation, titration calculation (using the 5.61 mg KOH per ml of 0.1 N NaOH factor), and common interferences. Mastery of RM principles is essential for quality control and analytical pharmacognosy. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What does the Reichert–Meissl (RM) value primarily measure?

• The amount of unsaturated fatty acids in a fat sample
• The amount of volatile short‑chain fatty acids distilled from a fat sample
• The iodine absorption capacity of fats
• The total ester content of oils

Correct Answer: The amount of volatile short‑chain fatty acids distilled from a fat sample

Q2. The RM value is usually expressed as:

• mg of KOH required to neutralize volatile fatty acids from 5 g of fat
• mg of NaOH required for 1 g of fat
• grams of free fatty acids per 100 g
• ml of iodine absorbed per 100 g

Correct Answer: mg of KOH required to neutralize volatile fatty acids from 5 g of fat

Q3. Typical sample mass used in the standard RM test is:

• 1 g
• 2 g
• 5 g
• 10 g

Correct Answer: 5 g

Q4. Which reagent receives the distilled volatile fatty acids during the RM procedure?

• Sodium chloride solution
• Boric acid solution
• Hydrochloric acid
• Phenolphthalein solution

Correct Answer: Boric acid solution

Q5. After distillation in the RM test, the volatile acids are titrated with:

• Standardized 0.1 N NaOH
• Standardized 0.1 N HCl
• Dilute sulfuric acid
• Standard 0.5 N KCl

Correct Answer: Standardized 0.1 N NaOH

Q6. Which short‑chain fatty acids mainly contribute to the RM value?

• Long‑chain C18 fatty acids
• Medium‑chain C10–C14 fatty acids
• Short‑chain C2–C6 fatty acids (e.g., acetic, butyric)
• Trans fatty acids only

Correct Answer: Short‑chain C2–C6 fatty acids (e.g., acetic, butyric)

Q7. A high RM value in a fat sample most likely indicates:

• Adulteration with vegetable oils
• High content of short‑chain volatile fatty acids typical of dairy fat
• High unsaturation index
• Excess moisture only

Correct Answer: High content of short‑chain volatile fatty acids typical of dairy fat

Q8. RM value is particularly useful in distinguishing:

• Olive oil from sunflower oil
• Pure dairy butterfat from vegetable fat adulterants
• Refined from unrefined vegetable oils
• Hydrogenated from non‑hydrogenated oils

Correct Answer: Pure dairy butterfat from vegetable fat adulterants

Q9. Which step is essential before steam distillation in the RM method?

• Saponification of the fat with alcoholic KOH
• Hydrogenation of the sample
• Drying by heating to 200°C
• Mixing with excess salt only

Correct Answer: Saponification of the fat with alcoholic KOH

Q10. The conversion factor when using 0.1 N NaOH to express RM as mg KOH per ml is approximately:

• 0.56 mg KOH per ml
• 5.61 mg KOH per ml
• 56.1 mg KOH per ml
• 1 mg KOH per ml

Correct Answer: 5.61 mg KOH per ml

Q11. How is the RM value calculated when 0.1 N NaOH is used and 8.0 ml was consumed?

• 8.0 × 0.561 mg = 4.488 mg KOH
• 8.0 × 5.61 mg = 44.88 mg KOH
• 8.0 × 56.1 mg = 448.8 mg KOH
• 8.0 × 1 mg = 8 mg KOH

Correct Answer: 8.0 × 5.61 mg = 44.88 mg KOH

Q12. An RM value lower than expected for butter suggests:

• Possible adulteration with low‑RM fats (vegetable oils)
• Presence of excessive short‑chain fatty acids
• Sample contamination with volatile alcohols
• Higher unsaturation level

Correct Answer: Possible adulteration with low‑RM fats (vegetable oils)

Q13. Which indicator can be used during titration of the RM distillate?

• Phenolphthalein
• Starch iodine
• Potassium permanganate
• Methylene blue only

Correct Answer: Phenolphthalein

Q14. RM value differs from saponification value because RM:

• Measures total fatty acid content
• Specifically quantifies volatile short‑chain fatty acids
• Is determined by iodine uptake
• Measures degree of esterification

Correct Answer: Specifically quantifies volatile short‑chain fatty acids

Q15. Which of the following can falsely elevate the RM value?

• Incomplete saponification
• Presence of volatile contaminants (e.g., acetic acid from spoilage)
• Adulteration with stearic acid‑rich fats
• Poorly standardized titrant with lower normality

Correct Answer: Presence of volatile contaminants (e.g., acetic acid from spoilage)

Q16. The main application of RM value in pharmacognosy and quality control is:

• Determining the antioxidant activity of oils
• Detecting milk fat authenticity and adulteration
• Measuring polymer residues in fats
• Determining water content only

Correct Answer: Detecting milk fat authenticity and adulteration

Q17. Which apparatus is essential for performing the RM test?

• Gas chromatograph
• Steam distillation setup (distillation flask, condenser)
• UV‑visible spectrophotometer
• Rotary evaporator only

Correct Answer: Steam distillation setup (distillation flask, condenser)

Q18. Reichert–Meissl value was originally developed to evaluate:

• Vegetable oil acidity
• Butter and dairy fat quality
• Essential oil purity
• Sugar solution concentration

Correct Answer: Butter and dairy fat quality

Q19. Which of the following is NOT directly assessed by the RM value?

• Presence of short‑chain fatty acids
• Degree of unsaturation of fatty acids
• Possible adulteration with non‑dairy fats
• Effectiveness of saponification and distillation steps

Correct Answer: Degree of unsaturation of fatty acids

Q20. During RM determination, incomplete distillation of volatile acids will cause the measured RM to be:

• Higher than the true value
• Lower than the true value
• Unaffected
• Randomly variable but usually higher

Correct Answer: Lower than the true value

Q21. The Reichert–Meissl test is most sensitive to which chain length of fatty acids?

• C16–C18
• C12–C14
• C2–C8
• All chain lengths equally

Correct Answer: C2–C8

Q22. Which sample conditioning improves accuracy of RM test?

• Heating sample to 300°C to remove volatiles
• Ensuring complete saponification with excess alcoholic KOH
• Adding extra water to the oil before saponification
• Filtering through activated charcoal

Correct Answer: Ensuring complete saponification with excess alcoholic KOH

Q23. If 0.1 N NaOH consumes 12.0 ml in titration, what is the RM value (mg KOH)?

• 12.0 × 0.561 = 6.732 mg
• 12.0 × 5.61 = 67.32 mg
• 12.0 × 56.1 = 673.2 mg
• 12.0 × 1 = 12 mg

Correct Answer: 12.0 × 5.61 = 67.32 mg

Q24. A typical RM range for pure butterfat is approximately:

• 1–5
• 5–10
• 17–28
• 80–100

Correct Answer: 17–28

Q25. Which of the following is a limitation of the RM test?

• It quantifies all fatty acids accurately
• It is non‑specific and can be affected by non‑fat volatile acids
• It requires sophisticated chromatography equipment
• It measures peroxide value instead

Correct Answer: It is non‑specific and can be affected by non‑fat volatile acids

Q26. The Reichert–Meissl test sequence typically includes:

• Hydrogenation → distillation → GC analysis
• Saponification → steam distillation → titration
• Cold filtration → centrifugation → mass spectrometry
• Direct titration of oil with iodine

Correct Answer: Saponification → steam distillation → titration

Q27. Which of the following samples would you expect to have the lowest RM value?

• Pure cow butterfat
• Ghee from milk fat
• Refined vegetable oil
• Sheep milk fat

Correct Answer: Refined vegetable oil

Q28. Which procedural error would decrease the RM value obtained?

• Using excessive boric acid in receiving solution
• Incomplete distillation of liberated volatile acids
• Using standardized 0.1 N NaOH
• Properly calibrating the burette

Correct Answer: Incomplete distillation of liberated volatile acids

Q29. In an RM test, the distillate is usually titrated until the end‑point indicated by:

• Development of a persistent pink color (phenolphthalein)
• Disappearance of turbidity
• Formation of a blue complex
• Release of gas bubbles

Correct Answer: Development of a persistent pink color (phenolphthalein)

Q30. The RM value helps detect adulteration of butter with which type of material?

• Mineral oils
• Vegetable fats and oils
• Salt
• Sugar syrups

Correct Answer: Vegetable fats and oils

Q31. Which quality control parameter is most complementary to RM value when assessing dairy fats?

• Iodine value (degree of unsaturation)
• pH only
• Viscosity at 100°C
• Density at 0°C

Correct Answer: Iodine value (degree of unsaturation)

Q32. RM value is particularly low in fats rich in:

• Short‑chain fatty acids
• Long‑chain saturated fatty acids
• Short‑chain volatile fatty acids
• Medium‑chain volatile acids

Correct Answer: Long‑chain saturated fatty acids

Q33. When reporting RM value, which of the following must be ensured for accuracy?

• Exact sample mass, proper standardization of NaOH, and complete distillation
• Only the use of GC‑MS
• Heating sample to dryness before saponification
• Using distilled water only for titration

Correct Answer: Exact sample mass, proper standardization of NaOH, and complete distillation

Q34. The presence of residual solvents in fat will most likely cause:

• No effect on RM
• Erroneous higher RM if volatile acidic solvents are present
• Always lower RM values
• Complete neutralization of titrant

Correct Answer: Erroneous higher RM if volatile acidic solvents are present

Q35. Which of the following best describes why RM value is still used despite modern techniques?

• It is fast, inexpensive and useful for routine screening of dairy fat authenticity
• It replaces the need for GC analysis entirely
• It measures unsaturation more accurately than GC
• It requires no trained personnel

Correct Answer: It is fast, inexpensive and useful for routine screening of dairy fat authenticity

Q36. The Reichert–Meissl number increases when the sample contains more:

• Stearic and palmitic acids
• Butyric and caproic acids
• Non‑volatile long‑chain esters
• Neutral triglycerides only

Correct Answer: Butyric and caproic acids

Q37. If titrant normality is changed from 0.1 N to 0.05 N NaOH without adjusting calculation, the reported RM will be:

• Correct regardless
• Approximately doubled
• Halved
• Unaffected because RM uses ml directly

Correct Answer: Approximately doubled

Q38. Which of the following describes the Reichert–Meissl method principle?

• Oxidative degradation of fats and measurement of CO2
• Release and quantification of water‑soluble volatile fatty acids after saponification and distillation
• Chromatographic separation of triglycerides
• Direct gravimetric measurement of free fatty acids

Correct Answer: Release and quantification of water‑soluble volatile fatty acids after saponification and distillation

Q39. An RM determination is performed; if titrant is not standardized, the main consequence is:

• Improved precision
• Systematic error in RM result (inaccurate value)
• No significant effect
• Color change interference only

Correct Answer: Systematic error in RM result (inaccurate value)

Q40. Which of the following fats would typically give an RM value similar to butterfat?

• Coconut oil (high short‑chain content)
• Soybean oil
• Olive oil
• Mineral oil

Correct Answer: Coconut oil (high short‑chain content)

Q41. Which analytical parameter directly measured in RM titration is converted to the RM index?

• Volume (ml) of 0.1 N NaOH used in titration
• Weight of fat sample after saponification
• Temperature at which distillation stops
• pH of the original fat

Correct Answer: Volume (ml) of 0.1 N NaOH used in titration

Q42. RM value is particularly low in which processed fat?

• Hydrogenated butter fat
• Refined vegetable oil devoid of milk fat
• Unprocessed cream
• Raw milk fat

Correct Answer: Refined vegetable oil devoid of milk fat

Q43. Which practice improves reproducibility of RM results between labs?

• Standardizing titrant normality and following identical sample mass and distillation conditions
• Using different sample masses randomly
• Skipping standardization to save time
• Changing indicators each run

Correct Answer: Standardizing titrant normality and following identical sample mass and distillation conditions

Q44. The presence of organic acids from microbial spoilage would most likely:

• Have no effect on RM
• Increase the RM value falsely
• Decrease the RM value falsely
• Cause formation of non‑volatile residues only

Correct Answer: Increase the RM value falsely

Q45. For regulatory screening of ghee authenticity, RM value is used because it:

• Directly measures glycerol content
• Reflects the content of characteristic volatile fatty acids of milk fat
• Is unaffected by blending with other fats
• Determines the melting point

Correct Answer: Reflects the content of characteristic volatile fatty acids of milk fat

Q46. Which calculation factor is used to convert ml of 0.1 N NaOH to mg KOH for RM reporting?

• 0.561
• 5.61
• 56.1
• 0.0561

Correct Answer: 5.61

Q47. If a lab uses a 10 g sample instead of 5 g and does not adjust calculations, the RM value reported will be:

• Twice the true value
• Half the true value
• Unchanged because RM is concentration independent
• Randomly variable

Correct Answer: Twice the true value

Q48. Which of the following steps should be controlled to avoid loss of volatile acids during sample handling?

• Avoid prolonged heating before saponification and store samples sealed at low temperature
• Expose samples to air on a hot plate
• Freeze‑dry the sample at room temperature
• Filter through fine mesh and leave uncovered

Correct Answer: Avoid prolonged heating before saponification and store samples sealed at low temperature

Q49. In method validation, RM precision is assessed by:

• Repeating the RM determination on replicate aliquots under the same conditions
• Measuring the RM once only
• Using different titrants each time
• Varying the sample mass randomly

Correct Answer: Repeating the RM determination on replicate aliquots under the same conditions

Q50. Which statement best summarizes the practical importance of RM value for B. Pharm students?

• RM is obsolete and has no role in modern pharmacopeias
• RM provides a simple, low‑cost screening for milk fat authenticity and short‑chain fatty acid content useful in quality control
• RM directly measures drug potency in fat‑based formulations
• RM replaces microbiological testing for contamination

Correct Answer: RM provides a simple, low‑cost screening for milk fat authenticity and short‑chain fatty acid content useful in quality control

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