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Mass Spectrometry Quiz

Mass Spectrometry Quiz

Test your knowledge on mass spectrometry and its history

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  • 1.
    Mass spectrometers known as calutrons were used for the industrial separation of uranium isotopes during the Manhattan Project. A large amount of copper was needed to make their magnetic coils. How was the highly-valued metal obtained during the war?

    Your answer:
    Correct answer:

    During the war, copper was preferably used for the production of brass shell casings and it was not available for the construction of calutrons. The designers came up with the idea of replacing copper with silver. They borrowed about 13,300 tons of silver from the West Point Bullion Depository in West Point, NY. After the war, the silver was returned to the Treasury with virtually no loss.

  • 2.
    The quadrupole mass filter has been known since the mid-1950s thanks to the work of Wolfgang Paul. The motion of ions in a quadrupole field can be described by solving second-order differential equations. When were these equations solved mathematically?

    Your answer:
    Correct answer:

    The solution of differential equations of this type came from the French mathematician Émile Léonard Mathieu (1835-1890), who studied the mechanical vibrations of the elliptical drumheads.

  • 3.
    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.
  • 4.
    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.

  • 5.
    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.

  • 6.
    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]

  • 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.
    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.

  • 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.
    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.

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