Chapter 3 Multiple Choice Questions

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. The relationship between m/z and magnetic field B in a sector mass spectrometer is:

m/z α B^1/2 correct incorrect

m/z α B correct incorrect

m/z α B² correct incorrect

m/z α B³ correct incorrect

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. The main function of an electrostatic analyser in a double-focussing sector mass spectrometer is to:

increase sensitivity correct incorrect

increase resolving power correct incorrect

prevent damage to the magnet correct incorrect

increase scan speed correct incorrect

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. A quadrupole mass analyser separates ions of differing m/z values by scanning:

the DC voltage correct incorrect

the RF voltage correct incorrect

both the DC and RF voltages correct incorrect

the magnetic field correct incorrect

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. The relationship between m/z and time of flight t in a TOF mass spectrometer is:

m/z α t ² correct incorrect

m/z α t correct incorrect

m/z α t ^1/2 correct incorrect

m/z α 1/t correct incorrect

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. Which of the following statements about ion trap analysers is correct?

Ion traps are beam analysers correct incorrect

Single ion trap analysers are capable of tandem MS (MS/MS) correct incorrect

Ion trap analysers have very slow scan rates correct incorrect

Ion trap analysers require an ultra-high vacuum correct incorrect

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. The relationship between m/z and ion cyclotron frequency f_c in an FTICR mass spectrometer is:

m/z α f_c correct incorrect

m/z α f_c ² correct incorrect

m/z α f_c ^1/2 correct incorrect

m/z α 1/ f_c correct incorrect

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. Orbitrap analysers measure m/z by:

detecting the oscillation of ions between electrodes correct incorrect

using a strong magnetic field to trap ions correct incorrect

deflecting ions onto an electron multiplier correct incorrect

recording the drift time f ion packets correct incorrect

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. The order of typical resolving power of the following mass analysers is (note: > means greater than):

quadrupole > time of flight > FTICR correct incorrect

time of flight > quadrupole > FTICR correct incorrect

FTICR > time of flight > quadrupole correct incorrect

time of flight > FTICR > quadrupole correct incorrect

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. The duty cycle of a mass spectrometer is:

equal to its scan rate correct incorrect

the amount of time ions take to travel from the source to the detector correct incorrect

the proportion of time (%) that the analyser spends actively collecting ions within the range of possible m/z values specified by the scan correct incorrect

the number of samples it can analyse per hour correct incorrect

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. The main advantage of reflectron TOF analysers over linear ToF analysers, of similar dimensions, is:

they are cheaper to manufacture correct incorrect

they have faster scan rates correct incorrect

they have an increased mass range correct incorrect

they have increased resolving power correct incorrect