MCQ on Analytical Techniques for Drug Quality Control

🟢 EASY (1–20)

1. Which technique is commonly used for determining the purity of a drug?
   a) Filtration
   b) Titration
   c) Spectroscopy ✅
   d) Crystallization
   Explanation: Spectroscopy helps determine drug concentration and purity.
2. HPLC stands for:
   a) High Performance Liquid Chromatography ✅
   b) High Pressure Level Chromatography
   c) High Phase Liquid Chromatography
   d) High Precision Level Chromatography
   Explanation: HPLC is a powerful technique for separating and analyzing compounds.
3. Which analytical technique measures absorbance of UV light?
   a) IR spectroscopy
   b) NMR spectroscopy
   c) UV-Visible spectroscopy ✅
   d) Mass spectrometry
   Explanation: UV-Vis spectroscopy detects compounds that absorb UV or visible light.
4. TLC stands for:
   a) Thin Liquid Chromatography
   b) Total Layer Chromatography
   c) Thin Layer Chromatography ✅
   d) Thermal Layer Chromatography
   Explanation: TLC is a simple method for separating small quantities of compounds.
5. Which of the following is a qualitative analysis method?
   a) pH meter
   b) Color reaction ✅
   c) Spectrophotometry
   d) Karl Fischer titration
   Explanation: Color reactions help identify the presence of specific functional groups.
6. Which method is most suitable for moisture content determination?
   a) UV Spectroscopy
   b) Mass spectrometry
   c) Karl Fischer titration ✅
   d) TLC
   Explanation: Karl Fischer titration quantifies water content in substances.
7. Which instrument measures the pH of a drug solution?
   a) Calorimeter
   b) Conductometer
   c) pH meter ✅
   d) Voltameter
   Explanation: A pH meter provides the hydrogen ion concentration.
8. Which technique separates components based on boiling points?
   a) Distillation ✅
   b) Chromatography
   c) Extraction
   d) Titration
   Explanation: Distillation separates compounds based on volatility.
9. Mass spectrometry provides information on:
   a) Molecular structure ✅
   b) Color
   c) Solubility
   d) Boiling point
   Explanation: It measures molecular weight and structural details.
10. The IR spectroscopy is used to identify:
    a) Ions
    b) Functional groups ✅
    c) Density
    d) Viscosity
    Explanation: IR spectra reveal bond vibrations in functional groups.
11. Which technique separates components based on polarity?
    a) IR spectroscopy
    b) Chromatography ✅
    c) Conductometry
    d) Polarimetry
    Explanation: Chromatography uses stationary and mobile phases to separate based on polarity.
12. What is the mobile phase in chromatography?
    a) The solid support
    b) The phase that remains stationary
    c) The solvent that moves the analyte ✅
    d) The detector
    Explanation: The mobile phase carries the analyte through the stationary phase.
13. Which of the following is a gravimetric method?
    a) Weighing the precipitate ✅
    b) Using color indicators
    c) Titrating a solution
    d) Measuring absorbance
    Explanation: Gravimetric methods involve isolating and weighing a solid.
14. Which technique is used to test drug dissolution?
    a) Spectroscopy
    b) Chromatography
    c) Dissolution apparatus ✅
    d) pH meter
    Explanation: Dissolution testing ensures drug release rate in the body.
15. Which analytical technique measures conductivity?
    a) Spectrophotometry
    b) Conductometry ✅
    c) Potentiometry
    d) TLC
    Explanation: Conductometry measures ionic content in solutions.
16. Which technique uses retention time as a parameter?
    a) Spectroscopy
    b) Titration
    c) Chromatography ✅
    d) IR analysis
    Explanation: Each compound has a unique retention time in chromatography.
17. LOD stands for:
    a) Loss on drying
    b) Level of decomposition
    c) Limit of detection ✅
    d) Line of diffusion
    Explanation: LOD is the smallest amount of substance that can be detected.
18. Which instrument is used in UV-Visible spectroscopy?
    a) Mass spectrometer
    b) Spectrophotometer ✅
    c) Thermometer
    d) Refractometer
    Explanation: A spectrophotometer measures absorbance of light.
19. Which is a wet chemical method?
    a) NMR
    b) Titration ✅
    c) UV spectroscopy
    d) HPLC
    Explanation: Titration involves liquid solutions and chemical reactions.
20. Which test is done to check uniformity in tablets?
    a) Moisture test
    b) Weight variation test ✅
    c) Disintegration test
    d) Solubility test
    Explanation: It checks if each tablet has consistent weight.

🟡 MODERATE (21–40)

21. Which detector is used in HPLC?
    a) UV detector ✅
    b) NMR detector
    c) Flame ionization detector
    d) Electron multiplier
    Explanation: UV detectors are commonly used to monitor eluents.
22. Which analytical method is used for structural elucidation?
    a) UV Spectroscopy
    b) HPLC
    c) NMR Spectroscopy ✅
    d) TLC
    Explanation: NMR helps identify carbon and hydrogen environments.
23. The wavelength range of UV light is:
    a) 200–400 nm ✅
    b) 500–800 nm
    c) 800–1000 nm
    d) 10–50 nm
    Explanation: UV region lies between 200–400 nm.
24. Which technique is best for separating volatile substances?
    a) TLC
    b) Gas Chromatography ✅
    c) IR
    d) HPLC
    Explanation: GC is used for separating volatile organic compounds.
25. Limit test in pharmacopoeia is meant for:
    a) Drug activity
    b) Drug stability
    c) Detecting impurities ✅
    d) Determining dose
    Explanation: Limits ensure impurity levels are below toxic thresholds.
26. Which of the following is a stability-indicating method?
    a) TLC
    b) HPLC ✅
    c) IR
    d) pH measurement
    Explanation: HPLC separates and quantifies degradation products.
27. What is the purpose of a blank in UV-Vis spectroscopy?
    a) Enhances reading
    b) Serves as standard
    c) Compensates for solvent absorbance ✅
    d) Cleans the cuvette
    Explanation: A blank corrects for solvent interference.
28. What is the purpose of the internal standard in chromatography?
    a) Increases retention
    b) Aids purification
    c) Corrects variation in analysis ✅
    d) Increases detection
    Explanation: Internal standards normalize results for more accurate quantification.
29. Which test ensures identity of a drug compound?
    a) Weight variation
    b) Limit test
    c) Identification test ✅
    d) Dissolution
    Explanation: Confirms the presence of the correct chemical.
30. LOD is usually:
    a) Higher than LOQ
    b) Lower than LOQ ✅
    c) Equal to LOQ
    d) Unrelated to LOQ
    Explanation: LOD is the minimum detectable amount; LOQ is the minimum quantifiable amount.
31. In IR spectra, the fingerprint region is:
    a) 600–1400 cm⁻¹ ✅
    b) 1400–2000 cm⁻¹
    c) 2000–2500 cm⁻¹
    d) 2500–4000 cm⁻¹
    Explanation: This region is unique for each molecule.
32. Which of the following tests is used for tablet friability?
    a) UV test
    b) Dissolution test
    c) Friabilator test ✅
    d) Karl Fischer test
    Explanation: Friabilator checks for resistance to abrasion.
33. Which of these is not an analytical technique?
    a) NMR
    b) HPLC
    c) Spectrophotometry
    d) Fermentation ✅
    Explanation: Fermentation is a biochemical process, not an analysis technique.
34. A calibration curve is used to:
    a) Adjust pH
    b) Find unknown concentrations ✅
    c) Weigh substances
    d) Filter solutions
    Explanation: It relates absorbance to concentration.
35. Which technique determines optical purity?
    a) HPLC
    b) Polarimetry ✅
    c) UV
    d) TLC
    Explanation: Polarimetry measures optical rotation of chiral compounds.
36. Retention factor (Rf) in TLC is calculated by:
    a) Solvent front / Sample front
    b) Sample front / Solvent front ✅
    c) Sample front × Solvent front
    d) Sample front + Solvent front
    Explanation: Rf = Distance moved by compound / distance moved by solvent.
37. Mass spectrometry fragments molecules to identify:
    a) Mass and structure ✅
    b) Polarity
    c) Solubility
    d) Charge
    Explanation: Fragments help determine molecular structure.
38. Which instrument uses magnetic fields?
    a) UV spectrophotometer
    b) IR spectrometer
    c) NMR spectrometer ✅
    d) HPLC
    Explanation: NMR uses a magnetic field to analyze nuclei.
39. Dissolution testing is critical for:
    a) Tablets and capsules ✅
    b) Solutions only
    c) Injections
    d) Creams
    Explanation: Ensures solid dosage forms release drug appropriately.
40. Which of the following detects chirality in molecules?
    a) IR
    b) UV
    c) Polarimetry ✅
    d) HPLC
    Explanation: Chiral compounds rotate plane-polarized light.

🔴 HARD (41–50)

41. Which is an advantage of HPLC over TLC?
    a) Lower cost
    b) Higher resolution ✅
    c) Simpler technique
    d) Requires no detector
    Explanation: HPLC gives precise separation and quantification.
42. What does a higher Rf value in TLC indicate?
    a) High polarity
    b) Low mobility
    c) High mobility ✅
    d) Large particle size
    Explanation: High Rf = moved farther = less polar.
43. Which detector is used in GC for organic compounds?
    a) UV detector
    b) Flame ionization detector ✅
    c) Mass spectrometer
    d) Thermal detector
    Explanation: FID detects organic substances with high sensitivity.
44. Which analytical method uses deuterated solvents?
    a) IR
    b) UV
    c) NMR ✅
    d) HPLC
    Explanation: NMR requires deuterated solvents to avoid proton interference.
45. Which method is best for quantifying a drug in plasma?
    a) Karl Fischer
    b) UV
    c) LC-MS/MS ✅
    d) TLC
    Explanation: LC-MS/MS is sensitive and specific for biological matrices.
46. Limit of quantification (LOQ) is defined as:
    a) Lowest detectable value
    b) Lowest quantifiable value ✅
    c) Average concentration
    d) Maximum solubility
    Explanation: LOQ ensures quantification with acceptable accuracy.
47. Which analytical method identifies elemental composition?
    a) UV
    b) AAS ✅
    c) HPLC
    d) NMR
    Explanation: Atomic Absorption Spectroscopy detects elements like Fe, Ca.
48. Which chromatography uses a supercritical fluid?
    a) GC
    b) SFC ✅
    c) HPLC
    d) TLC
    Explanation: Supercritical Fluid Chromatography uses CO₂ for efficient separation.
49. System suitability tests are performed to:
    a) Calibrate instruments
    b) Prepare reagents
    c) Ensure performance of analytical system ✅
    d) Label samples
    Explanation: It checks the analytical system before sample analysis.
50. Potentiometry involves measurement of:
    a) Temperature
    b) Light
    c) Voltage ✅
    d) Weight
    Explanation: It measures the potential difference in electrochemical cells.