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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 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.

  • 2.
    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.
  • 3.
    What is the base peak in the mass spectrum?

    Your answer:
    Correct answer:

    The base peak is the peak with the greatest intensity among all peaks in the spectrum. The intensity of each peak in the spectrum is expressed as a percentage relative to the intensity of the base peak.

  • 4.
    List these compounds according to their increasing mass: hydrazine (H4N2), oxygen (O2), methanol (CH4O).

    Your answer:
    Correct answer:

    The monoisotopic masses of these compounds are 31.989829 Da (oxygen), 32.026215 Da (methanol), and 32.037448 Da (hydrazine).

  • 5.
    Which mass spectrometer was carried by the American spacecraft Viking 1 sent to the planet Mars in 1975?

    Your answer:
    Correct answer:
    Viking 1 carried two mass spectrometers, both equipped with double-focusing analyzers and electron ionization sources. The first spectrometer with a Mattauch-Herzog geometry was designed by Alfred Nier; it was intended to analyze the upper atmosphere of Mars. The second one with a Nier- Johnson geometry was part of the GC/MS apparatus designed by Klaus Biemann. It was used to analyze the regolith and the atmosphere at the landing site.
  • 6.
    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.

  • 7.
    What was the largest number of quadrupoles connected in series for tandem mass spectrometry in a commercial instrument?

    Your answer:
    Correct answer:
    A penta-quadrupole mass spectrometer contains three quadrupole filters and two rf-only quadrupole collision cells. It allows MS3 experiments.  Extrel once offered such a spectrometer.
  • 8.
    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.

  • 9.
    Chemical ionization (CI) is a soft ionization technique used in mass spectrometry. Who discovered it?

    Your answer:
    Correct answer:

    Chemical ionization was discovered in the laboratories of the Humble Oil and Refining Company in Baytown, TX. Munson and Field’s seminal paper on chemical ionization was published in 1966.  [https://doi.org/10.1021/ja00964a001]

  • 10.
    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]

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