General Mass Spectrometry

Question 1

Mass Spectrometry

Answer 1

• an analytical technique which utilizes a mass spectrometer to measure the mass and quanitity of ions

Question 2

Mass Spectrometer

Answer 2

• an instrument which measures the mass-to-charge ratio (m/z) and abundance of gas-phase ions

Question 3

Unified Atomic Mass Unit (u, dalton (Da))

Answer 3

• one-twelth the mass of one atom of C¹²
• approximately 1.66x10^-27kg

Question 4

Mass-to-Charge-Ratio (m/z)

Answer 4

• a quantity obtained by dividing the ratio of the mass of an ion to the unified atomic mass unit by its charge number
• (MassOfIon/UnifiedAtomicMass)/ChargeNumber

Question 5

Mass Spectrometer Components

Answer 5

1. Ion Source
2. Mass Analyzer
3. Detector

Question 6

Ion Source

Answer 6

• unit which converts molecules to gas-phase ions of (+) or (-) charge

Question 7

Mass Analyzer

Answer 7

• unit which separates ions according to their different m/z ratios

Question 8

Detector

Answer 8

• unit which detects and quantifies ions according to their m/z and abundance

Question 9

Base Peak

Answer 9

• the most intense (abundant) ion in the spectrum which is assigned a relative abundance of 100%

Question 10

Relative Abundance

Answer 10

• the abundance of an ion relative to that of the base peak
• this value is expressed on the y-axis

Question 11

Absolute Ion Signal

Answer 11

• the measured signal of an ion which is often expressed in arbitrary digital units

Question 12

Percent of Total Ion Current (%TIC)

Answer 12

• the abundance of an individual ion expressed as a percent of the sum of all the ion abundances within a specified mass range

Question 13

Monoisotopic Mass (Molecular Weight)

Answer 13

• mass based upon the most abundant isotope of each element in the moleculat formula

Question 14

Average Mass (Formula Weight)

Answer 14

• mass based upon the weighted average of all isotopes of each element in the molecular formula

Question 15

Isotopic Pattern (z)

Answer 15

• z = 1/(Delta(m/z))