Chapter 6 - LC/MS: fundamentals, perspectives, and applications

Question 1

A standard MS consists of what 3 components

Answer 1

1. Ion source
2. Mass analyzer
3. Detection system

Question 2

Resolving power (RP)

Answer 2

the ability of an MS instruments to perform the separation of adjacent ions.

Question 3

Mass spectral resolution (R)

Answer 3

Defined by the mass of a peak divided by its full width at half maximum (FWHM) in Dalton or atomic mass unit.

Question 4

Unit resolution

Answer 4

The resolving power necessary to separate two adjacent ions one mass unit apart.

Question 5

Nominal mass

Answer 5

The sum of the integer masses of the constituent elements of a compound.

Question 6

Average mass

Answer 6

The weighted average of the molecular masses of the analyte.

Question 7

Monoisotopic mass

Answer 7

The mass of the structure based on the most abundant isotope for each element.

Question 8

Mass error equation

Answer 8

Mass error = theoretical mass - measured mass

Question 9

Mass accuracy in ppm equation

Answer 9

Mass accuracy in ppm = mass error/theoretical mass x 10⁶

Question 10

To calculate the molecular formula effectively, a mass accuracy of less than ____ ppm is typically required.

Answer 10

5

Question 11

ESI is used in ______% of LC/MS applications.

Answer 11

80-90

Question 12

a, b, c ions are formed with the positive charge on the

Answer 12

N-terminus.

Question 13

x, y, z ions are formed with the positive charge on the

Answer 13

C-terminus.

Question 14

Bottom-up protein analysis is also called

Answer 14

peptide mapping

Question 15

In bottom up proteomics, proteins are fragmented by

Answer 15

enzymes.

Question 16

In top-down proteomics, proteins are fragmented by

Answer 16

gas-phase fragmentation in the MS.