Chapter 2 Multiple Choice Questions

* not completed

. What is the primary purpose of ionization in a mass spectrometer?

To facilitate fragmentation of the analyte in the ion source correct incorrect

To ensure a radical is formed from the analyte correct incorrect

To ensure the analyte is volatile enough to enter the gas phase. correct incorrect

To be able to manipulate the analyte inside the mass spectrometer and facilitate mass measurement and detection. correct incorrect

* not completed

. What is meant by the term 'hard ionization'?

An ionization technique which involves electrons impacting the analyte molecule. correct incorrect

An ionization technique transferring a relatively large amount of energy to the analyte. correct incorrect

An ionization technique transferring very little energy to the analyte correct incorrect

An ionization technique which forms many fragment ions. correct incorrect

* not completed

. What is the name used to refer to the type of ion represented by: M^+.

A cation correct incorrect

A radical correct incorrect

A protonated molecule correct incorrect

A radical cation correct incorrect

* not completed

. What is the typical energy of the electrons used to ionize analytes by Electron Ionization (EI)?

50 eV correct incorrect

70 eV correct incorrect

1 eV correct incorrect

1000 eV correct incorrect

* not completed

. Which of the following classifies Chemical Ionization most accurately

A hard ionization technique correct incorrect

A soft ionization technique correct incorrect

neither hard or soft ionization correct incorrect

A desorption ionization technique correct incorrect

* not completed

. What does 'ICP-MS' stand for?

Inductively coupled plasma mass spectrometry correct incorrect

Inductively coupled proton mass spectrometry correct incorrect

Intensively coupled plasma mass spectrometry correct incorrect

Interaction coupled proton mass spectrometry correct incorrect

* not completed

. What is the purpose of the matrix in MALDI ionization?

To provide a suitable solvent for the analyte correct incorrect

To promote multiple ion formation correct incorrect

To absorb laser energy and form radical ions correct incorrect

To enable the analyte to crystalize correct incorrect

* not completed

. Name an ionization technique which uses a coronal discharge needle to form molecular ions prior to charge transfer with an analyte

Electrospray Ionization correct incorrect

Atmospheric Pressure Photoionization correct incorrect

Matrix –Assisted Laser Desorption Ionization correct incorrect

Atmospheric Pressure Chemical Ionization correct incorrect

* not completed

. What are 'matrix effects' that are associated with electrospray ionization?

Matrix effects are the interference of other molecules in a sample on the number of ions formed from an analyte. correct incorrect

The matrix effect leads to the formation of a Taylor cone during electrospray ionization correct incorrect

The matrix effect relates to the coulombic repulsion in a solvent droplet as it evaporates in an electric field correct incorrect

Matrix effects are the interference caused by the electric field during electrospray ionization. correct incorrect

* not completed

. Which of the following is a characteristic of ambient ionization techniques?

Occurs in the vacuum of the mass spectrometer. correct incorrect

Direct analysis if the sample with little or no sample preparation. correct incorrect

Always uses a matrix to enhance sensitivity correct incorrect

Tends to exploit 'hard ionization' mechanisms correct incorrect