Chapter 5 Multiple Choice Questions

. Ions generated by soft ionization techniques, such as electrospray ionization, often require additional activation to dissociate because:

the ions possess relatively low kinetic energies

energy is dissipated through more bonds

the ions possess relatively low internal energies

soft ionization is used to analyse very stable molecules only

. Which of the following statements most accurately describes the data plotted in a Wahrhaftig diagram:

the probability distribution of energies (P(E)) for a population of ions as a function of the rate of ion dissociation (log k(E))

the rate of ion dissociation (log k(E)) )) as a function of energy E

the rate of ion dissociation (log k(E)) )) as a function of molecular mass

the probability distribution of energies (P(E)) for a population of ions and the rate of ion dissociation (log k(E)) as a function of energy E

. The E_lab energy of an ion with +2 charge state accelerated by a collision voltage of 20 V is:

10 eV

20 eV

30 eV

40 eV

. The centre of mass energy E_com of an ion of mass 1,500 Da and E_lab energy 50 eV undergoing a single collision with an atom of Ar (39.96 Da) is:

1.10 eV

1.20 eV

1.30 eV

1.40 eV

. Electron capture dissociation (ECD) is often said to yield complementary information to collision induced dissociation (CID) in MS/MS analysis because:

ECD is slower, but more sensitive

ECD uses multiply charged ions

ECD fragmentation occurs by a different mechanism from CID, and generates different product ions

ECD can only be used with cations, whereas CID can be used with anions

. For a tandem (triple) quadrupole mass spectrometer operating in precursor ion scanning mode, the scanning arrangement of quadrupoles Q1 and Q3 is:

Q1 is set to transmit a particular precursor ion m/z, and Q3 is scanned

Q3 is set to transmit a particular product ion m/z and Q1 is scanned

Both Q1 and Q3 are scanned with an m/z offset

Q1 and Q3 are held in RF-only mode

. What is the name of the approach to tandem mass analysis which enables successive fragmentation of product ions?

MS^e

MS/MS

DDA

MSⁿ

. Why is DDA analysis particularly useful when using hyphenated technique such as GC-MS or LC-MS?

Because it provides more accurate tandem mass spectra when the compounds are separated

It provides fast switching between positive and negative ion mode to enable greater tandem mass spectral coverage.

It provides significant tandem mass spectral coverage of complex samples in an automated way.

DDA standards for De-convoluted Data Analysis, which uses an algorithm to provide greater coverage using hyphenated techniques.

. What does the term SRM mean?

Single Reaction Monitoring

Selective Reaction Monitoring

Selective Reaction Mass measurement

Single Reaction Mass measurement

. Name one of the benefits of DIA analysis compared to DDA in the LC-MS/MS analysis of a complex mixture.

Data independent analysis (DIA) allows for automated ms/ms analysis by selection of precursor ions

Data independent analysis (DIA) provides higher tandem mass spectral coverage of eluting compounds

Data independent analysis (DIA) provides lower background noise

Data independent analysis (DIA) provides continuous analysis enables tandem mass spectral analysis of unknown analytes.

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