Exam 1

Question 1

3 ionization methods

Answer 1

1. gas-phase
2. desorption
3. evaporative

Question 2

Electron Impact

Answer 2

-gas-phase ionization method
-M+ ion formed
-Advantages: Data base searchable, structural information
-Disadvantages:
M+ occasionally absent

Question 3

Chemical Ionization

Answer 3

• gas-phase ionization method
• M+1, M+18 formed
• Advantage: M+ usually present
• Disadvantage: Little structural information

Question 4

Field Desorption

Answer 4

• Desorption Ionization method
• M+ formed
• Advantage: Nonvolatile compounds
• Disadvantage: Need specialized equipment

Question 5

Fast Atom Bombardment

Answer 5

-Desorption ionization method
-M+1, M+ matrix, M+ cation formed
-Advantage: Nonvolatile Compounds, sequencing information
Disadvantage: Matrix interference, difficult to interpret

Question 6

Plasma Desorption

Answer 6

• desorption ionization method
• M+
• Advantages: Nonvolatile Compounds
• Disadvantages: Matrix interference

Question 7

Laser Desorption

Answer 7

• Desorption method
• M+1, M+ matrix
• Advantages: Nonvolatile compounds, bursts of ions
• Disadvantages: matrix interference

Question 8

Thermospray

Answer 8

• Evaporative method
• M+
• Advantages: Nonvolatile compounds
• Disadvantages: Outdated

Question 9

Electrospray

Answer 9

• Evaporative method
• M+, M++, M+++
• Advantages: Nonvolatile compounds interfaces with LC, forms multiply charged ions
• Disadvantages: limited classes of compounds, little structural information

Question 10

5 types of mass analyzers

Answer 10

1. Magnetic Sector
2. quadrupole
3. ion trap
4. time of flight
5. fourier transformation

Question 11

Magnetic Sector

Answer 11

• Mass Range: 1-15000 m/z
• Resolution: 0.0001
• Sensitivity: Low
• Advantage: High resolution
• Disadvantage: Low sensitivity, very expensive, high technical expertise

Question 12

Quadrupole

Answer 12

• Mass range: 1-5000 m/z
• Resolution: Unit
• Sensitivity: High
• Advantages: easy to use, inexpensive, high sensitivity
• Disadvantages: Low resolution, low mass range

Question 13

Ion trap

Answer 13

• Mass Range: 1-5000 m/z
• Resolution: Unit
• Sensitivity: High
• Advantages: easy to use, inexpensive, high sensitivity, Tandem (MS)
• Disadvantages: low resolution, low mass range

Question 14

Time of Flight

Answer 14

• mass range: unlimited
• resolution: 0.0001
• sensitivity: high
• advantages: high mass range, simple design
• Disadvantage: very high resolution

Question 15

Fourier Transform

Answer 15

• mass range: up to 70 kDa
• resolution: 0.0001
• sensitivity: high
• advantage: very high resolution and mass range
• disadvantage: very expensive, high technical expertise

Question 16

5 common features of mass spectrometer

Answer 16

1. Computer System
2, Sample Introduction
3. Ionization Method
4. ion separation method
5. detector

Question 17

How does hydrogen bonding affect infrared spectroscopy

Answer 17

Alters the stretching and bending vibrations

Question 18

2 Types of IR

Answer 18

• Dispersion IR

- Fourier Transform

Question 19

Important factors to consider when preparing an IR sample

Answer 19

• liquid can be neat or in solution
• solutions handled in cells of 0.1-1 mm thickness
• solvent must be dry and transparent in region of interest
• solids can be examined as mull, pressed disk, glassy film, or as powders

Question 20

requirements for data to consider before interpreting IR

Answer 20

1. spectrum must be adequately resolved and of adequate intensity
2. spectrum should be of reasonably pure compound
3. spectrometer should be calibrated so bands are observed at proper frequencies or wavelengths
4. method of sample handling must be specified