instrumental analysis

Question 1

what is mass spectrometry

Answer 1

This is an analytical technique used to identify different isotopes and find the overall relative
atomic mass of an element.

Question 2

time of flight (TOF)

Answer 2

This form of mass spectrometry records the time it takes for ions of each isotope to reach a detector. Using this, spectra can be produced showing each isotope present. T

Question 3

the process of TOF in mass spectrometry

Answer 3

1. Ionisation - A sample of an element is vapourised and injected into the mass
   spectrometer where a high voltage is passed over the chamber. This causes electrons
   to be removed from the atoms (they are ionised) leaving +1 charged ions in the
   chamber.
2. Acceleration - The positively charged ions are accelerated towards a negatively
   charged plate.
3. Ion Drift - The ions are deflected by a magnetic field into a curved path. The radius of
   their path is dependent on the charge and mass of the ion.
4. Detection - When the positive ions hit the detection plate, they gain an electron
   producing a flow of charge. The greater the abundance, the greater the current
   produced.
5. Analysis - The current values are then used in combination with the flight times to
   produce a spectra print-out with the relative abundance of each isotope displayed.

Question 4

what is produced during the ionisation process

Answer 4

2+ charged ion
]This means it will be
affected more by the magnetic field producing a curved path of smaller radius. As a result, its mass to charge ratio (m/z) is halved and this can be seen on spectra as a trace at half the expected m/z value

Question 5

how is relative atomic mass calculated

Answer 5

Ar= m/z x abundance / total abundance

Question 6

high resolution mass spectra

Answer 6

This is a much more sensitive form of mass spectrometry which allows the Mr of a substance to be determined to several decimal places. Precise atomic masses are given which can then be used to calculate the molecular formula of the compound being tested, using the same method as above.

Question 7

infrared spectroscopy

Answer 7

This analytical technique uses infrared (IR) radiation to determine the functional groups
present in organic compounds. The IR radiation is passed through a sample where the different types of bonds absorb radiation in different amounts.
spectrum is produced with characteristic curves