1
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Instrumental Analysis Questions and
Answers (100% Correct Answers) Already
Graded A+
What is a molecular ion? [ Ans: ] a radical ion, formed by loss of
one e⁻ after collision with a stream of other e⁻. The molecular ion
has the same molecular mass as the molecule
What is fragmentation? [ Ans: ] Relaxation of newly formed
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excited state molecular ions by breaking up to produce ions of
lower masses.
What is rearrangement? [ Ans: ] process that occurs when a
Guru01 - Stuvia
fragment still has a lot of energy and must lose that energy in
some way
What ions are attracted through the slit of a mass spectrometer? [
Ans: ] positive ions
What are daughter ions? [ Ans: ] the lower-mass ions formed by
extensive fragmentation of the molecular ion during its relaxation
following its EI-induced formation
What is a base peak? [ Ans: ] The largest peak on a spectrum,
which is arbitrarily assigned a value of 100 This peak corresponds
to the most abundant ion in the sample, presumably formed by
breaking the weakest bond in the structure
What is a peak's relative intensity? [ Ans: ] a measure of that
peak's height (intensity) as a percentage of the base-peak height
What are collision product peaks? [ Ans: ] ∙peaks at higher mass
numbers than that of the molecular ion, resulting from ion-
molecule collisions
What peak is produced by the protonated molecular ion collision
product (transfer of H atom to the molecular ion)? [ Ans: ] ∙an
enhanced (M+1)⁺ peak
, 2
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What determines the height of the (M+1)⁺ collision product peak
formed by protonation of the molecular ion? [ Ans: ] This transfer
is a second-order reaction, and the amount of product depends
strongly on the reactant concentration. Consequently, the height
of this (M + 1)⁺ peak increases much more rapidly with increases in
sample pressure than do the heights of other peaks, make it
possible to detect this atom-transfer reaction
What is a hard ionization source? [ Ans: ] ionization sources that
impart enough energy to analyte molecules to leave them in a
highly excited energy state. Relaxation then involves rupture of
bonds, producing fragment ions that have mass-to- charge ratios
less than that of the molecular ion.
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What is a soft ionization source? [ Ans: ] ∙cause little
fragmentation
∙usually produces the molecular ion and only a few, if any, other
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peaks
What are ionizing agents for MS? [ Ans: ] the mechanisms used
to ionize the sample
What are gas-phase sources? [ Ans: ] With a gas-phase source,
the sample is first vaporized and then ionized
What is required in order to use gas-phase sources? [ Ans: ] ∙the
sample must be converted to the gas phase (vaporized) for the
ionization process
∙restricted to thermally stable compounds with boiling points less
than about 500°C
What are desorption sources? [ Ans: ] with desorption sources,
solid or liquid samples are converted directly into gaseous ions
Where does the sample come from before being introduced to
the ionization source? [ Ans: ] it can be directly introduced to
the ionization source or it can come fro another separation
method like GC
What are the axis variables on a molecular mass spectrum? [
Ans: ] x= m/z
For Expert help and assignment solutions, +254707240657
Instrumental Analysis Questions and
Answers (100% Correct Answers) Already
Graded A+
What is a molecular ion? [ Ans: ] a radical ion, formed by loss of
one e⁻ after collision with a stream of other e⁻. The molecular ion
has the same molecular mass as the molecule
What is fragmentation? [ Ans: ] Relaxation of newly formed
© 2025 Assignment Expert
excited state molecular ions by breaking up to produce ions of
lower masses.
What is rearrangement? [ Ans: ] process that occurs when a
Guru01 - Stuvia
fragment still has a lot of energy and must lose that energy in
some way
What ions are attracted through the slit of a mass spectrometer? [
Ans: ] positive ions
What are daughter ions? [ Ans: ] the lower-mass ions formed by
extensive fragmentation of the molecular ion during its relaxation
following its EI-induced formation
What is a base peak? [ Ans: ] The largest peak on a spectrum,
which is arbitrarily assigned a value of 100 This peak corresponds
to the most abundant ion in the sample, presumably formed by
breaking the weakest bond in the structure
What is a peak's relative intensity? [ Ans: ] a measure of that
peak's height (intensity) as a percentage of the base-peak height
What are collision product peaks? [ Ans: ] ∙peaks at higher mass
numbers than that of the molecular ion, resulting from ion-
molecule collisions
What peak is produced by the protonated molecular ion collision
product (transfer of H atom to the molecular ion)? [ Ans: ] ∙an
enhanced (M+1)⁺ peak
, 2
For Expert help and assignment solutions, +254707240657
What determines the height of the (M+1)⁺ collision product peak
formed by protonation of the molecular ion? [ Ans: ] This transfer
is a second-order reaction, and the amount of product depends
strongly on the reactant concentration. Consequently, the height
of this (M + 1)⁺ peak increases much more rapidly with increases in
sample pressure than do the heights of other peaks, make it
possible to detect this atom-transfer reaction
What is a hard ionization source? [ Ans: ] ionization sources that
impart enough energy to analyte molecules to leave them in a
highly excited energy state. Relaxation then involves rupture of
bonds, producing fragment ions that have mass-to- charge ratios
less than that of the molecular ion.
© 2025 Assignment Expert
What is a soft ionization source? [ Ans: ] ∙cause little
fragmentation
∙usually produces the molecular ion and only a few, if any, other
Guru01 - Stuvia
peaks
What are ionizing agents for MS? [ Ans: ] the mechanisms used
to ionize the sample
What are gas-phase sources? [ Ans: ] With a gas-phase source,
the sample is first vaporized and then ionized
What is required in order to use gas-phase sources? [ Ans: ] ∙the
sample must be converted to the gas phase (vaporized) for the
ionization process
∙restricted to thermally stable compounds with boiling points less
than about 500°C
What are desorption sources? [ Ans: ] with desorption sources,
solid or liquid samples are converted directly into gaseous ions
Where does the sample come from before being introduced to
the ionization source? [ Ans: ] it can be directly introduced to
the ionization source or it can come fro another separation
method like GC
What are the axis variables on a molecular mass spectrum? [
Ans: ] x= m/z
