Deck 14: Mass Spectrometry

Question 1

Which of the following corresponds to the molecular ion in EI mass spectrometry?

A)the most abundant ion
B)the ion with the smallest m/e
C)the ion formed by removal of an electron from the molecule
D)any ion formed by fragmentation of the molecule

Answer 1

the ion formed by removal of an electron from the molecule

Question 2

Which of the following is not prominent in the mass spectrum of 2-methyl-2-butanol?

A)M - 29
B)M- 18
C)M - 15
D)M - 12

Answer 2

M - 12

Question 3

Which of the following bonds of the octane radical cation is least subject to fragmentation?

A)i
B)ii
C)iii
D)iv

Answer 3

i

Question 4

Which of the following sets of molecular ions does an alkyl bromide possess?

A)two molecular ions in a 2:1 ratio separated by two mass units
B)two molecular ions in a 1:1 ratio separated by two mass units
C)three molecular ions in a 1:2:1 ratio separated by two mass units
D)two molecular ions in a 3:1 ratio separated by two mass units

Question 5

How many carbon atoms are present in a molecule which gives an M+1 peak that is 5.74% of the intensity of the molecular ion?

A)5
B)6
C)11
D)12

Question 6

What are products of the collision between high energy electrons and methane?

A)CH₄1^- + 2 e^-
B)CH₃^-. + H^.
C)CH₄⁺S1^. + 2 e^-
D)CH₃^.+ H⁺ + 2 e^-

Question 7

What is the y-axis of a mass spectrum?

A)mass
B)energy
C)abundance
D)field strength

Question 8

Which of the molecules gives rise to a molecular ion with an odd value of m/z?

A)C₆H₁₂O₂
B)C₇H₁₀ClN
C)C₈H₁₈N₂
D)C₈H₁₂

Question 9

Which of the following is the definition of the base peak of a mass spectrum?

A)the peak corresponding to the most abundant ion
B)the peak corresponding to the ion with lowest m/e
C)the peak corresponding to the molecular ion peak
D)the peak corresponding to the ion arising to loss of a proton from the molecular ion

Question 10

What are the most common products of the fragmentation of a molecular ion?

A)two radicals
B)an anion and a cation
C)a radical and a cation
D)two cations

Question 11

Which of the following sets of molecular ions does an alkyl chloride possess?

A)two molecular ions in a 2:1 ratio separated by two mass units
B)two molecular ions in a 1:1 ratio separated by two mass units
C)three molecular ions in a 1:2:1 ratio separated by two mass units
D)two molecular ions in a 3:1 ratio separated by two mass units

Question 12

In mass spectrometry, which of the following phrases is shortened to the acronym "MALDI"?

A)mass analysis by light-detected ions
B)matrix assisted laser desorption ionization
C)many atom loss-detecting ionization
D)molecular and light detecting instrument

Question 13

Which of the molecules gives rise to a molecular ion with an odd value of m/z?

A)C₆H₁₂Cl₂
B)C₇H₁₀N₂
C)C₈H₁₃N
D)C₈H₁₄Br₂

Question 14

What is the x-axis of a mass spectrum?

A)mass
B)mass/energy
C)mass/charge
D)charge

Question 15

Which of the following sets of molecular ions does a dibromoalkane possess?

A)two molecular ions in a 2:1 ratio separated by two mass units
B)two molecular ions in a 1:1 ratio separated by two mass units
C)three molecular ions in a 1:2:1 ratio, separated by two mass units
D)two molecular ions in a 3:1 ratio separated by two mass units

Question 16

In mass spectrometry, which of the following phrases is shortened to the acronym "EI"?

A)electron injection
B)electron impact
C)energy initiated
D)energy insertion

Question 17

What is the principle that allows us to use mass spectrometry to determine the molecular weight of a compound?

A)higher molecular weight compounds are less volatile
B)higher molecular weight compounds are more dense
C)a beam of higher molecular weight cations is deflected less by a magnetic field
D)ions with higher molecular weight absorb higher frequencies of light

Question 18

How many carbon atoms are present in a molecule which gives an M+1 peak that is 11.48% of the intensity of the molecular ion?

A)5
B)6
C)11
D)12

Question 19

In mass spectrometry, which of the following phrases is shortened to the acronym "FAB"?

A)flight averaged bumping
B)fast atom bombardment
C)fragmented atom beam
D)flying atom bashing

Question 20

Which of the following is most consistent with a molecule having a molecular ion with m/e of 77?

A)the molecule contains bromine
B)the molecule contains nitrogen
C)the molecule is an alcohol
D)the molecule is a hydrocarbon

Question 21

Which of the following is not prominent in the mass spectrum of 2-methyl-2-butanol?

A)M - 15
B)M - 18
C)M - 21
D)M - 29

Question 22

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 91?

A)1-octene
B)1-hexanamine, CH₃CH₂CH₂CH₂CH₂CH₂NH₂
C)benzene
D)ethylbenzene

Question 23

Which of the following gives rise to a prominent peak in the mass spectrum at m/z of 39?

A)1-octyne
B)4-octyne
C)5-methyl-3-octyne
D)2,2-dimethyl-3-heptyne

Question 24

Alpha cleavage of the following compound would produce fragments at m/z = 43 and m/z = 119.

Question 25

Which of the following gives rise to a prominent M - 15 peak in the mass spectrum?

A)cyclopentane
B)cyclopentene
C)cyclopentanol
D)methylcyclopentane

Question 26

It is not possible distinguish 2,2-dimethylbutane from 2-methylpentane using mass spectrometry.

Question 27

Which of the following gives rise to a prominent M - 18 peak in the mass spectrum?

A)cyclohexane
B)cyclohexene
C)1-chlorocyclohexane
D)cyclohexanol

Question 28

Which of the following does not give rise to a prominent M - 41 peak in the mass spectrum?

A)1-hexene
B)3-methyl-1-hexene
C)4-methyl-1-hexene
D)5-methyl-1-hexene

Question 29

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 45?

A)1-hexanol
B)2-hexanol
C)hexanal
D)hexanoic acid

Question 30

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 41?

A)1-hexene
B)2-hexyne
C)3-hexanol
D)2-chlorohexane

Question 31

Both mass spectrometry and infrared spectroscopy involve the interaction of molecules with electromagnetic energy.

Question 32

Loratidine is the active ingredient in the antihistamine Claritin®. Mass spectral analysis of loratidine shows M⁺ at m/z = 382 and M⁺ at m/z = 384 in an approximate ratio of 3:1 in intensity. This data indicates that loratidine contains fluorine.

Question 33

C₆H₁₅N could have a mass spectrum with M⁺ at m/z = 101 with a minor M+1 peak.

Question 34

Which of the following gives rise to a prominent M - 18 peak in the mass spectrum?

A)hexane
B)1-chloropentane
C)1-pentanol
D)3-methylpentane

Question 35

Which of the following gives rise to a prominent M - 15 peak in the mass spectrum?

A)hexane
B)1-chloropentane
C)1-pentanol
D)3-methylpentane

Question 36

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 43?

A)1-hexanol
B)2-hexanol
C)hexanal
D)hexanoic acid

Question 37

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 60?

A)1-hexanol
B)2-hexanol
C)hexanal
D)hexanoic acid

Question 38

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 30?

A)1-hexanamine, CH₃CH₂CH₂CH₂CH₂CH₂NH₂
B)1,1-dimethyl-1-butanamine, CH₃CH₂CH₂C⁽CH₃⁾₂NH₂
C)1-hexanol
D)hexanal

Question 39

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of M - 31?

A)2-methylhexanoic acid
B)methyl hexanoate
C)ethyl hexanoate
D)hexanoic acid

Question 40

Which of the following alcohols does not give a prominent M - 15 ion?

A)isopropyl alcohol
B)tert-butyl alcohol
C)2-hexanol
D)3-pentanol

Question 41

The following question(s) refer to the mass spectrum shown below. Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The base peak in this spectrum occurs at a m/z of ______.

Question 42

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Dehydration of the following compound will produce a peak at a m/z of _______.

Question 43

A monochloroalkane shows two parent ion peaks m/z at 92 and 94. The molecular formula of this compound might be C₃H₇Cl.

Question 44

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Cyclohexene and hex-2-yne both have the molecular formula, C₆H₁₀. The mass spectrum below belongs to ___________________.

Question 45

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The peak at a m/z of _____ represents the base peak.

Question 46

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The peak at a m/z of _____ represents the following species.
+CH₂CH₃

Question 47

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The peak at a m/z of _____ represents M⁺.

Question 48

The following question(s) refer to the mass spectrum shown below. Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
This compound contains C, H, and one other atom. The other atom from the mass spectrum is __________.

Question 49

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Alpha cleavage of the following compound will produce a peak at a m/z of _______.

Question 50

The mass spectrum of 1-pentanol shows an intense daughter ion peak at m/z = 31. This peak could be due to the formation of CH₃O⁺.

Question 51

What is the most likely molecular formula of a compound that has a molecular ion in the EI mass spectrum with m/z of 97 and an M+1 peak that is 6.6% of the intensity of the molecular ion peak?

Question 52

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The mass of the larger charged fragment produced by the dehydration of the following compound occurs at a m/z of _______.

Question 53

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The peak at a m/z of _____ represents the following species.

Question 54

What is the most likely molecular formula of a compound that has a molecular ion in the EI mass spectrum with m/z of 136, with a M+1 and M+2 peaks that are 4.4% and 49% of the intensity of the molecular ion peak, respectively.

Question 55

Provide the mass of the three most prominent fragment peaks that are observed in the EI mass spectrum of 2-hexanone, CH₃CH₂CH₂CH₂COCH₃ (molecular ion m/z = 100) and describe the processes that lead to each of these fragments.

Question 56

What is the most likely molecular formula of a compound that has a molecular ion in the EI mass spectrum with m/z of 120, with a M+1 and M+2 peaks that are 6.6% and 24% of the intensity of the molecular ion peak, respectively.

Question 57

Mass spectrometry and infrared spectroscopy are complementary techniques because mass spectrometry provides information about the molar mass and formula while infrared spectroscopy helps identify the functional groups in the formula.

Question 58

What is the most likely molecular formula of a compound (that contains only C, H and O) which has a molecular ion in the EI mass spectrum with m/z of 104 and an M+1 peak that is 5.5% of the intensity of the molecular ion peak?

Question 59

Consider the following mass spectrum C₅H₁₂O might have been used to produce this spectrum.

Question 60

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
The peak at a m/z of _____ represents the following species.

Question 61

Which C₅H₁₂O compound give the following EI mass spectrum?

Question 62

Provide the mass of the three most prominent fragment peaks that are observed in the EI mass spectrum of methyl pentanoate, CH₃CH₂CH₂CH₂CO₂CH₃ (molecular ion m/z = 116) and describe the processes that lead to each of these fragments.

Question 63

Which C₆H₁₂O carbonyl-containing compound shows a molecular ion peak at m/z 100 and significant fragment peaks at m/z 71, 58, 57, 43 and 29 in the EI mass spectrum?

Question 64

Which C₅H₁₂O compound give the following EI mass spectrum?

Question 65

Which C₆H₁₂O carbonyl-containing compound shows a molecular ion peak at m/z 100 and significant fragment peaks at m/z 85, 58, 57, 43 and 42 in the EI mass spectrum?