Mass spectrometry techniques: MALDI, ESI and EPR

1. 1What is an isotopomer?

   1. ATwo molecules that differ by arrangement of isomers
   2. BSame chemical formula but different isotopes
2. 2Which of the following is false about Electron Impact ionisation?

   1. ASample must have a low vapour pressure as it is vaporized into the mass spectrometer
   2. BA beam of electrons then impacts the sample to ionise it
   3. CIt is commonly used with CO ligand complexes
   4. DIt is limited to charged molecules
3. 3Which of the following is an explanation for how MALDI works?

   1. ASample molecules are co-crystallised in a matrix such as dithranol
   2. BSample is vaporized and then impacted by a beam of electrons
   3. CIt is a hard ionisation method
4. 4For the MALDI technique the matrix has a small molar absorption coefficient

   1. ATrue
   2. BFalse
5. 5MALDI technique involves proton transfer to the analyte

   1. ATrue
   2. BFalse
6. 6MALDI requires internal charges to start with

   1. ATrue
   2. BFalse
7. 7MALDI is a soft technique that leads to little fragmentation

   1. ATrue
   2. BFalse
8. 8Which of the following best describes the method of electrospray?

   1. ASpray of charged droplets produced which passes through flow of drying gas to evaporate solvent
   2. BSample co crystallised in a matrix
   3. CThe sample is vaporised
9. 9In ES no fragmentation occurs and a sequence of peaks can be seen, if there is a gap of 2 the it must be a +2 species

   1. ATrue
   2. BFalse
10. 10What is cone voltage?

    1. AAccelerates ions relative to neutral gas molecules
    2. BThe voltage at which the ms is conducted at
    3. Cresults in non energetic collisions

11. 11Which of the following are bad points of the ES technique?

    1. AVery sensitive to contaminants hence poor reproducability
    2. BSpectrum can be confusing with so many peaks at one point
    3. CMass range of up to 100kDa
    4. DGood for polar, basic compounds which can easily be charged
12. 12Which of the following have the shortest timescale?

    1. ANMR
    2. BIR
    3. CEPR
13. 13The principle used in the EPR technique is that compounds with one unpaired electrons have two states: +0.5, -0.5

    1. ATrue
    2. BFalse
14. 14The zeeman effect results in the equation:

    1. AE=g*mu*B
    2. BE=g*y*h
15. 15Hyperfine coupling is the interaction between the electron and the nuclei

    1. ATrue
    2. BFalse

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Quiz on Untitled, created by nicola.bowen on 19/11/2015.

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