Analytical techniques (chromatography, spectroscopy) MCQs Food science

1. What does chromatography primarily separate?

a) Mixtures into individual components
b) Solids from liquids
c) Gases into different phases
d) Nutrients from non-nutrients
Answer: a) Mixtures into individual components

2. Which of the following is a type of chromatography where the stationary phase is a liquid coated on a solid support?

a) Gas chromatography
b) Liquid chromatography
c) Thin-layer chromatography
d) High-performance liquid chromatography
Answer: c) Thin-layer chromatography

3. In gas chromatography (GC), what is typically used as the mobile phase?

a) Liquid solvent
b) Solid support
c) Gas
d) Gel
Answer: c) Gas

4. Which type of chromatography uses a liquid mobile phase and a solid stationary phase?

a) Gas chromatography
b) Liquid chromatography
c) Supercritical fluid chromatography
d) Thin-layer chromatography
Answer: b) Liquid chromatography

5. What is the primary purpose of using a detector in chromatography?

a) To identify and quantify the separated components
b) To separate the components
c) To prepare the sample
d) To enhance the separation efficiency
Answer: a) To identify and quantify the separated components

6. What does the term “retention time” refer to in chromatography?

a) The time a compound takes to pass through the chromatographic system
b) The time taken to prepare the sample
c) The time required for the detector to analyze the compound
d) The duration of the experiment
Answer: a) The time a compound takes to pass through the chromatographic system

7. Which type of chromatography is commonly used for separating complex mixtures in food science?

a) Gas chromatography
b) Liquid chromatography
c) Paper chromatography
d) Column chromatography
Answer: b) Liquid chromatography

8. In high-performance liquid chromatography (HPLC), what is the role of the pump?

a) To move the mobile phase through the chromatographic column
b) To separate the sample components
c) To detect the components
d) To prepare the sample
Answer: a) To move the mobile phase through the chromatographic column

9. Which type of detector in HPLC is based on measuring UV light absorption?

a) UV-Vis detector
b) Fluorescence detector
c) Refractive index detector
d) Conductivity detector
Answer: a) UV-Vis detector

10. What is the main principle of mass spectrometry (MS)?

a) To measure the mass-to-charge ratio of ions
b) To separate components based on their size
c) To measure the light absorption of compounds
d) To detect changes in the compound’s viscosity
Answer: a) To measure the mass-to-charge ratio of ions

11. Which technique combines chromatography with mass spectrometry for detailed analysis of compounds?

a) Gas chromatography-mass spectrometry (GC-MS)
b) Liquid chromatography-mass spectrometry (LC-MS)
c) Thin-layer chromatography-mass spectrometry (TLC-MS)
d) High-performance liquid chromatography-mass spectrometry (HPLC-MS)
Answer: b) Liquid chromatography-mass spectrometry (LC-MS)

12. What does “spectroscopy” measure in analytical techniques?

a) Interaction of light with matter
b) Separation of components
c) The mass of ions
d) The viscosity of a sample
Answer: a) Interaction of light with matter

13. Which type of spectroscopy is used to identify functional groups in organic compounds?

a) Infrared (IR) spectroscopy
b) Ultraviolet-visible (UV-Vis) spectroscopy
c) Nuclear magnetic resonance (NMR) spectroscopy
d) Mass spectrometry (MS)
Answer: a) Infrared (IR) spectroscopy

14. What is the primary use of ultraviolet-visible (UV-Vis) spectroscopy in food science?

a) To determine the concentration of compounds based on their light absorption
b) To separate different food components
c) To measure the mass of food particles
d) To analyze the viscosity of food products
Answer: a) To determine the concentration of compounds based on their light absorption

15. Which type of spectroscopy provides information about the molecular structure of compounds by analyzing their magnetic properties?

a) Nuclear magnetic resonance (NMR) spectroscopy
b) Infrared (IR) spectroscopy
c) Ultraviolet-visible (UV-Vis) spectroscopy
d) Mass spectrometry (MS)
Answer: a) Nuclear magnetic resonance (NMR) spectroscopy

16. What does the “chromatographic peak area” in a chromatogram indicate?

a) The quantity of the compound present in the sample
b) The time taken for the compound to elute
c) The purity of the compound
d) The interaction of the compound with the stationary phase
Answer: a) The quantity of the compound present in the sample

17. Which type of chromatography is best suited for separating gases?

a) Gas chromatography
b) Liquid chromatography
c) Thin-layer chromatography
d) Column chromatography
Answer: a) Gas chromatography

18. What is the main advantage of using liquid chromatography (LC) over other chromatography techniques?

a) It can separate a wide range of compounds with high resolution
b) It is faster than gas chromatography
c) It requires less sample preparation
d) It is less expensive than other techniques
Answer: a) It can separate a wide range of compounds with high resolution

19. Which of the following detectors in GC measures compounds based on their thermal conductivity?

a) Thermal conductivity detector (TCD)
b) Flame ionization detector (FID)
c) Electron capture detector (ECD)
d) Mass spectrometer (MS)
Answer: a) Thermal conductivity detector (TCD)

20. In UV-Vis spectroscopy, what does the absorbance value represent?

a) The amount of light absorbed by the sample
b) The amount of light transmitted through the sample
c) The sample’s refractive index
d) The temperature of the sample
Answer: a) The amount of light absorbed by the sample

21. What is the role of the stationary phase in chromatography?

a) To separate the sample components based on their interactions
b) To move the mobile phase through the column
c) To detect the separated components
d) To prepare the sample for analysis
Answer: a) To separate the sample components based on their interactions

22. Which technique uses a silica gel or alumina plate as the stationary phase?

a) Thin-layer chromatography (TLC)
b) Gas chromatography (GC)
c) High-performance liquid chromatography (HPLC)
d) Supercritical fluid chromatography (SFC)
Answer: a) Thin-layer chromatography (TLC)

23. What is the primary purpose of using a column in chromatography?

a) To separate the different components of the sample
b) To prepare the sample for analysis
c) To enhance the sensitivity of the detector
d) To stabilize the mobile phase
Answer: a) To separate the different components of the sample

24. Which technique is best for detecting trace amounts of compounds in complex mixtures?

a) Mass spectrometry (MS)
b) Ultraviolet-visible (UV-Vis) spectroscopy
c) Infrared (IR) spectroscopy
d) Nuclear magnetic resonance (NMR) spectroscopy
Answer: a) Mass spectrometry (MS)

25. What is “resolution” in the context of chromatography?

a) The ability to distinguish between two closely spaced peaks
b) The speed of the chromatographic process
c) The amount of sample required
d) The sensitivity of the detector
Answer: a) The ability to distinguish between two closely spaced peaks

26. Which type of chromatography is used for separating proteins and peptides?

a) High-performance liquid chromatography (HPLC)
b) Gas chromatography (GC)
c) Thin-layer chromatography (TLC)
d) Supercritical fluid chromatography (SFC)
Answer: a) High-performance liquid chromatography (HPLC)

27. In NMR spectroscopy, what information does the chemical shift provide?

a) The environment of specific nuclei in the molecule
b) The mass of the sample
c) The wavelength of absorbed light
d) The concentration of the compound
Answer: a) The environment of specific nuclei in the molecule

28. Which of the following is a key feature of high-performance liquid chromatography (HPLC)?

a) High resolution and sensitivity for analyzing compounds
b) Low cost of equipment
c) Ability to analyze only gases
d) Use of a solid stationary phase only
Answer: a) High resolution and sensitivity for analyzing compounds

29. What is the purpose of a calibration curve in spectroscopy?

a) To determine the concentration of unknown samples based on their absorbance
b) To separate different components in a mixture
c) To adjust the temperature during analysis
d) To enhance the resolution of the chromatographic peaks
Answer: a) To determine the concentration of unknown samples based on their absorbance

30. Which type of detector in HPLC is used for detecting compounds that do not absorb UV light?

a) Refractive index detector (RID)
b) UV-Vis detector
c) Fluorescence detector
d) Conductivity detector
Answer: a) Refractive index detector (RID)

31. In gas chromatography, what is the purpose of the injector?

a) To introduce the sample into the chromatographic column
b) To separate the components
c) To detect the components
d) To move the mobile phase
Answer: a) To introduce the sample into the chromatographic column

32. Which type of spectroscopy provides information about the molecular vibrations and rotations of a compound?

a) Infrared (IR) spectroscopy
b) Ultraviolet-visible (UV-Vis) spectroscopy
c) Nuclear magnetic resonance (NMR) spectroscopy
d) Mass spectrometry (MS)
Answer: a) Infrared (IR) spectroscopy

33. Which detector in GC is used to measure compounds that are not easily ionized?

a) Electron capture detector (ECD)
b) Flame ionization detector (FID)
c) Thermal conductivity detector (TCD)
d) Mass spectrometer (MS)
Answer: a) Electron capture detector (ECD)

34. What is the primary benefit of using supercritical fluid chromatography (SFC)?

a) It combines properties of both gases and liquids, offering high efficiency and resolution
b) It is less expensive than other chromatography techniques
c) It requires no sample preparation
d) It is limited to only non-polar compounds
Answer: a) It combines properties of both gases and liquids, offering high efficiency and resolution

35. What does “peak area” in chromatography represent?

a) The quantity of a particular compound in the sample
b) The time taken for the compound to elute
c) The temperature of the sample
d) The interaction of the compound with the stationary phase
Answer: a) The quantity of a particular compound in the sample

36. Which type of NMR spectroscopy provides information about the molecular dynamics and flexibility of compounds?

a) Solid-state NMR
b) Solution-state NMR
c) High-resolution NMR
d) Multi-dimensional NMR
Answer: b) Solution-state NMR

37. Which of the following is an advantage of using UV-Vis spectroscopy?

a) It is quick and requires minimal sample preparation
b) It provides detailed structural information
c) It can detect compounds at very low concentrations
d) It separates complex mixtures
Answer: a) It is quick and requires minimal sample preparation

38. What is the function of the mobile phase in chromatography?

a) To carry the sample through the stationary phase
b) To separate the sample components
c) To detect the separated components
d) To prepare the sample for analysis
Answer: a) To carry the sample through the stationary phase

39. Which chromatography technique is most suitable for analyzing volatile compounds?

a) Gas chromatography (GC)
b) Liquid chromatography (LC)
c) Thin-layer chromatography (TLC)
d) High-performance liquid chromatography (HPLC)
Answer: a) Gas chromatography (GC)

40. In chromatography, what does “selectivity” refer to?

a) The ability of the stationary phase to differentiate between different compounds
b) The amount of sample required
c) The time taken for the analysis
d) The type of detector used
Answer: a) The ability of the stationary phase to differentiate between different compounds

41. Which type of spectroscopy can provide information about the electronic structure of a molecule?

a) Ultraviolet-visible (UV-Vis) spectroscopy
b) Infrared (IR) spectroscopy
c) Nuclear magnetic resonance (NMR) spectroscopy
d) Mass spectrometry (MS)
Answer: a) Ultraviolet-visible (UV-Vis) spectroscopy

42. What does “peak height” in a chromatogram typically indicate?

a) The concentration of a compound in the sample
b) The time required for elution
c) The temperature of the column
d) The purity of the compound
Answer: a) The concentration of a compound in the sample

43. Which technique uses a mobile phase that is supercritical fluid?

a) Supercritical fluid chromatography (SFC)
b) Gas chromatography (GC)
c) Liquid chromatography (LC)
d) Thin-layer chromatography (TLC)
Answer: a) Supercritical fluid chromatography (SFC)

44. In mass spectrometry, what does “molecular ion peak” represent?

a) The peak corresponding to the molecule with its original mass-to-charge ratio
b) The peak corresponding to fragmented ions
c) The peak indicating the presence of a solvent
d) The peak indicating the presence of impurities
Answer: a) The peak corresponding to the molecule with its original mass-to-charge ratio

45. Which detector in HPLC is used for compounds that exhibit fluorescence?

a) Fluorescence detector
b) UV-Vis detector
c) Refractive index detector
d) Conductivity detector
Answer: a) Fluorescence detector

46. What is the primary purpose of using a gradient elution in HPLC?

a) To improve separation efficiency by gradually changing the mobile phase composition
b) To increase the sample preparation time
c) To reduce the analysis time
d) To enhance the sensitivity of the detector
Answer: a) To improve separation efficiency by gradually changing the mobile phase composition

47. In IR spectroscopy, which region is typically used to identify functional groups?

a) Fingerprint region
b) High-wavenumber region
c) Low-wavenumber region
d) Absorption region
Answer: a) Fingerprint region

48. What does “chromatographic resolution” measure?

a) The ability to distinguish between two closely spaced peaks in a chromatogram
b) The overall analysis time
c) The amount of sample required
d) The sensitivity of the detector
Answer: a) The ability to distinguish between two closely spaced peaks in a chromatogram

49. Which chromatography technique is known for its high sensitivity and resolution?

50. In UV-Vis spectroscopy, what does a higher absorbance value indicate?

a) A higher concentration of the absorbing species in the sample
b) A lower concentration of the absorbing species in the sample
c) A lower molecular weight of the absorbing species
d) A shorter wavelength of the absorbed light
Answer: a) A higher concentration of the absorbing species in the sample

Analytical techniques (chromatography, spectroscopy) MCQs Food science

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