Mass spectrometer/TOF

Question 1

what is a mass spectrometer?

Answer 1

a machine used to analyse elements or compounds
giving you the information about the relative atomic mass of an element and the relative abundance of its isotopes or the relative molecular mass of a molecule if you use it to analyse a compound

Question 2

when a sample is put in a TOF mass spectrometer what are the four stages in order?

Answer 2

-ionisation
-acceleration
-ion drift
-detection

Question 3

Their are two types of ionisation what are there and describe them?

Answer 3

-Electrospray ionisation, in this method the sample is dissolved in a solvent and pushed through a small nozzle at high pressure. A high voltage is applied to it, causing each particle to gain a H+ ion. The solvent is then removed, leaving a gas made up of positive ions

-electron impact ionisation, in this method , the sample is vaporised and an ‘electron gun’ is used to fire high energy electrons at it. This knocks one electron off one each particle, so they become +1 ions

Question 4

describe acceleration?

Answer 4

The ions are accelerated using an electric field so that all the ions have the same kinetic energy

Question 5

give me the formula for kinetic energy?

Answer 5

1/2mv squared

Question 6

describe ion drift?

Answer 6

next, the ions enter a region with no electric field (flight tube). They drift through it at the same speed as they left the electric field, so the lighter ions will be drifting at higher speeds.

Question 7

describe detection?

Answer 7

Because lighter ions travel through the drift region at higher speeds, they reach the detector in less time than heavier ions. The detector detects the current created when the ion hits it and records how long they took to pass through the spectrometer. This date is used to calculate the mass/charge values needed to produce a mass spectrum.