MPharm Master of Pharmacy Master of Pharmacy: Pharmaceutical Analysis and Quality Control 4 — Questions and Answers
Question 1: In mass spectrometry, what does 'base peak' refer to?
- The molecular ion peak at highest m/z
- The most abundant ion fragment in the spectrum (set to 100% relative abundance) (Correct answer)
- The ion peak used for calibration purposes
- The heaviest isotope peak in the spectrum
Correct answer: The most abundant ion fragment in the spectrum (set to 100% relative abundance)
The base peak is the most intense ion in the mass spectrum, assigned 100% relative abundance, against which all other peaks are compared.
Question 2: What is the primary purpose of using an internal standard in analytical methods like HPLC or GC?
- To extend the linear range of the calibration curve
- To compensate for variability in sample preparation and instrument response (Correct answer)
- To act as a system suitability marker for peak resolution
- To identify unknown impurity peaks by retention time
Correct answer: To compensate for variability in sample preparation and instrument response
An internal standard is added at a known concentration to correct for losses and variability during sample preparation and injection.
Question 3: Which USP test specifically evaluates particulate contamination in injectable pharmaceutical preparations?
- Bacterial endotoxin test
- Sterility test
- Light obscuration particle count test (Correct answer)
- Osmolarity test
Correct answer: Light obscuration particle count test
The light obscuration particle count test (USP <788>) measures subvisible particles in injectable solutions using laser-based detection.
Question 4: In pharmaceutical stability testing per ICH Q1A, what storage condition defines 'accelerated' stability testing for Zone IV climatic conditions?
- 25°C ± 2°C / 60% RH ± 5%
- 30°C ± 2°C / 65% RH ± 5%
- 40°C ± 2°C / 75% RH ± 5% (Correct answer)
- 50°C ± 2°C / 85% RH ± 5%
Correct answer: 40°C ± 2°C / 75% RH ± 5%
Accelerated stability testing for products intended for hot/humid climates (Zone IV) is conducted at 40°C/75% RH for 6 months.
Question 5: What analytical principle underlies the Kjeldahl method used in pharmaceutical analysis?
- Oxidation of sulfur-containing amino acids for protein estimation
- Acid digestion followed by distillation to determine nitrogen content (Correct answer)
- Enzymatic hydrolysis of peptide bonds for amino acid quantification
- Gravimetric precipitation of nitrogen as ammonium sulfate
Correct answer: Acid digestion followed by distillation to determine nitrogen content
The Kjeldahl method digests organic nitrogen with sulfuric acid, converts it to ammonium, then distills and titrates to quantify total nitrogen.
Question 6: In FTIR spectroscopy, what is the purpose of the 'fingerprint region' (400–1500 cm⁻¹)?
- Identification of functional groups like O-H, N-H, and C=O
- Unique molecular identification through complex vibrational patterns (Correct answer)
- Quantification of drug content in solid dosage forms
- Detection of water of crystallization in hydrates
Correct answer: Unique molecular identification through complex vibrational patterns
The fingerprint region contains unique, complex absorption patterns that serve as a molecular 'fingerprint' for identity confirmation of pharmaceutical substances.
Question 7: What does 'limit of detection' (LOD) represent in analytical method validation?
- The lowest concentration that can be quantified with defined precision and accuracy
- The lowest concentration reliably distinguished from zero signal (signal-to-noise ≈ 3:1) (Correct answer)
- The upper limit where the method becomes non-linear
- The minimum sample amount needed for a single analysis
Correct answer: The lowest concentration reliably distinguished from zero signal (signal-to-noise ≈ 3:1)
LOD is the smallest analyte concentration distinguishable from background noise, typically estimated at a signal-to-noise ratio of 3:1.
MPharm Master of Pharmacy Master of Pharmacy: Pharmaceutical Analysis and Quality Control 4
In mass spectrometry, what does 'base peak' refer to?