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Mass Spectrometry Quiz

Mass Spectrometry Quiz

Test your knowledge on mass spectrometry and its history

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  • 1.
    What is the trajectory of a charged particle moving parallel to a uniform electric field in a vacuum?

    Your answer:
    Correct answer:

    If a positive charge is moving in the same direction as the electric field vector the particle's velocity will increase. If it is moving in the opposite direction it will decelerate. If a negative charge is moving in the same direction as the electric field vector the particle will decelerate. If it is moving in the opposite direction it will accelerate.

  • 2.
    Lunar craters are usually named after scientists and explorers. One of the craters on the Moon is named after a prominent scientist in the field of mass spectrometry. Who is named after?

    Your answer:
    Correct answer:

    Aston is a 44-kilometer lunar impact crater located along the northwestern limb of the Moon. The crater was named in honor of Francis W. Aston.

  • 3.
    What principle of positive ray detection was used in the first Thomson's parabola spectrographs?

    Your answer:
    Correct answer:

    In the spectrographs used by Thomson until 1910, the rays of positive electricity were detected by the phosphorescence they produced on a willemite screen. The screen was made by grinding rare zinc mineral willemite into a fine powder. After shaking in alcohol, the suspension was allowed to deposit slowly on a glass plate. Later, a photographic plate inside the spectrograph was used for more sensitive detection.

  • 4.
    How long would be a paper needed for printing a profile mass spectrum measured in the m/z 0 1000 range at a resolution of 50,000 at m/z 500 if the peaks were to be 1 mm wide at their half maximum? Let us consider a constant width of all peaks.

    Your answer:
    Correct answer:

    The resolution can be expressed as (m/z)/Δ(m/z), where Δ (m/z) is the peak width at 50 % of its maximum. For a resolution of 50,000 at m/z 500, the value of Δ(m/z) is 0.01. If the Δ(m/z) is to correspond to 1 mm, then the total width of the spectral record equals 1000/0.01 mm, which is 100,000 mm, which is 100 m.

  • 5.
    Which element has the largest number of stable isotopes?

    Your answer:
    Correct answer:
    Naturally occurring tin is a mixture of its ten stable isotopes and they are found in the percentages as follows: 112Sn (1.0 %), 114Sn (0.7 %), 115Sn (0.3 %), 116Sn (14.5 %), 117Sn (7.7 %), 118Sn (24.2 %), 119Sn (8.6 %), 120Sn (32.6 %), 122Sn (4.6 %), and 124Sn (5.8 %). Molybdenum has six stable isotopes, ytterbium seven.

  • 6.
    What is the trajectory of a charged particle moving perpendicularly to a uniform magnetic field in a vacuum?

    Your answer:
    Correct answer:

    The magnetic force is perpendicular to the velocity so that it does no work on the charged particle. The particle’s kinetic energy and speed thus remain constant. The direction of motion is affected but not the speed.

  • 7.
    What ionization technique was used for the first sequencing of peptides by mass spectrometry?

    Your answer:
    Correct answer:

    Mass spectrometry was used to sequence peptides for the first time in 1959 when K. Biemann described an innovative method based on the reduction of small peptides to polyamino alcohols with characteristic EI spectra. [https://doi.org/10.1021/ja01518a069]

  • 8.
    Who made molecular elephants fly?

    Your answer:
    Correct answer:
    John Fenn was awarded Nobel Prize in Chemistry in 2002 for his work related to electrospray ionization of biological macromolecules. His famous phrase, "we made elephants fly" refers to the ability of electrospray to generate gas-phase ions from big protein molecules.

  • 9.
    The first on-line coupling of gas chromatography to a mass spectrometer was reported in 1959. What type of spectrometer was used for this purpose?

    Your answer:
    Correct answer:
    The first GC/MS experiments were carried out by Fred McLafferty and Roland Gohlke at Dow Chemical with Bill Wiley and Ian McLaren at Bendix Research Laboratories. They used a Bendix timeof- flight mass spectrometer, which had been commercially introduced in 1956. The instrument was fast enough to keep up with the changing output of the GC column.

  • 10.
    Who first reported the fragmentation after the gamma hydrogen rearrangement to an unsaturated group via a sixmembered intermediate?

    Your answer:
    Correct answer:
    It was first reported by Australian A. J. C. Nicholson in 1954 (Trans. Faraday Soc. 50: 1067-1073). The reaction description was published five years later (Anal. Chem. 1959, 31: 82–87) by the American chemist Fred McLafferty, by whose name we now refer to the rearrangement (McLafferty rearrangement).

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