MASS SPEC

Question 1

What is mass spectrometry used for?

Answer 1

It measures the mass-to-charge ratio (m/z) of ions to determine the molecular weight, structure, and composition of compounds.

Question 2

What are the three essential functions of a mass spectrometer?

Answer 2

Ion generation: Converts molecules into ions.
Ion separation: Sorts ions by their m/z ratio.
Ion detection: Measures the abundance of ions.

Question 3

What is Electrospray Ionization (ESI)?

Answer 3

A soft ionization technique often used with HPLC.
Generates ions with minimal fragmentation.
Can produce both positive and negative ions.

Question 4

What is Matrix-Assisted Laser Desorption Ionization (MALDI)?

Answer 4

Uses a laser to ionize molecules, typically for high-molecular-weight compounds like proteins.
Produces singly charged ions.

Question 5

How does Electron Impact Ionization (EI) work?

Answer 5

High-energy electrons ionize molecules, causing significant fragmentation.
Useful for generating a unique “fingerprint” spectrum of a compound.

Question 6

How does a magnetic sector analyzer separate ions?

Answer 6

It uses a magnetic field to curve the flight path of ions. The radius of the path depends on the ion’s m/z ratio.

Question 7

What is the principle of Time-of-Flight (TOF) separation?

Answer 7

Smaller ions travel faster and reach the detector first, while larger ions take longer.

Question 8

What is a quadrupole analyzer?

Answer 8

A device using two perpendicular electric fields to separate ions by their m/z ratio. It is cheaper and more sensitive than magnetic sector analyzers.

Question 9

What does the term “base peak” refer to in a mass spectrum?

Answer 9

The most intense ion peak in the spectrum, assigned an abundance of 100%

Question 10

What is the “molecular ion” in mass spectrometry?

Answer 10

The ion with the highest m/z value, representing the molecular weight of the compound.

Question 11

How do isotopes appear in a mass spectrum?

Answer 11

Isotopes create additional peaks at slightly higher or lower m/z values due to their different masses.

Question 12

What is the McLafferty rearrangement?

Answer 12

A common fragmentation pattern in compounds with carbonyl groups, such as ketones, amides, and esters.

Question 13

How do heteroatoms affect fragmentation?

Answer 13

Heteroatoms (e.g., N, O, S) localize radical cations, influencing fragmentation patterns

Question 14

List some applications of mass spectrometry in pharmaceuticals.

Answer 14

Drug discovery and metabolism studies.
Pharmacokinetics and impurity detection.
Analysis of active pharmaceutical ingredients (APIs).

Question 15

How is mass spectrometry used in clinical and environmental fields?

Answer 15

Clinical: Neonatal screening, drug testing, cancer biomarker analysis.
Environmental: Detecting pollutants in air, water, and food.

Question 16

Define “mass-to-charge ratio (m/z).”

Answer 16

The ratio of the ion’s mass to its charge, used to identify ions in mass spectrometry.

Question 17

What is “relative abundance” in mass spectrometry?

Answer 17

The intensity of an ion peak compared to the base peak, expressed as a percentage.

Question 18

What is the main purpose of mass spectrometry?
A. To determine the pH of a solution.
B. To measure the mass-to-charge ratio (m/z) of ions.
C. To separate compounds by polarity.
D. To analyze optical properties of molecules.

Answer 18

b

Question 19

Which ionization technique is most commonly paired with high-pressure liquid chromatography (HPLC)?
A. Electron Impact Ionization (EI)
B. Matrix-Assisted Laser Desorption Ionization (MALDI)
C. Electrospray Ionization (ESI)
D. Time-of-Flight (TOF)

Answer 19

c

Question 20

What is the “base peak” in a mass spectrum?
A. The ion peak with the smallest m/z ratio.
B. The ion peak with the highest m/z ratio.
C. The ion peak representing the molecular ion.
D. The ion peak with the highest intensity, assigned 100% abundance.

Answer 20

d

Question 21

How does the Time-of-Flight (TOF) analyzer separate ions?
A. By using a magnetic field to curve ion paths.
B. By accelerating ions through a quadrupole filter.
C. By measuring the time it takes ions to travel a fixed distance.
D. By fragmenting ions into smaller parts.

Answer 21

C

Question 22

Which ionization technique is considered a “soft” ionization method with minimal fragmentation?
A. Electron Impact Ionization (EI)
B. Electrospray Ionization (ESI)
C. Chemical Ionization (CI)
D. Plasma Desorption Ionization (PDI)

Answer 22

B

Question 23

Which of the following isotopes is most likely to create a distinct peak in a mass spectrum?
A. C 12
B. N 15
C. C 13
D. H1

Answer 23

C

Question 24

What is the McLafferty rearrangement?
A. A process in which ions are separated by their m/z ratio.
B. A fragmentation pattern involving carbonyl compounds like ketones and esters.
C. A rearrangement of ions to form a molecular ion.
D. A technique to analyze isotopic variations.

Answer 24

B

Question 25

What information can be obtained from a mass spectrum?
A. Molecular weight and fragmentation patterns.
B. Color and polarity of the compound.
C. pKa and boiling point of the compound.
D. Only the mass of isotopes.

Answer 25

A

Question 26

Why are isotopes of bromine and chlorine easily distinguishable in a mass spectrum?
A. They are the only isotopes that form ions.
B. They have distinct isotopic abundances and masses.
C. They do not create molecular ions.
D. Their isotopes are always radioactive.

Answer 26

B

Question 27

Which of the following is a primary clinical application of mass spectrometry?
A. Determining the viscosity of fluids.
B. Quantifying nucleic acids.
C. Neonatal screening and drug testing.
D. Measuring solubility of pharmaceutical compounds.

Answer 27

C