Interpreting a Mass Spectrum

Question 1

Mass spectroscopy is an analytical technique used to identify

Answer 1

unknown compounds

Question 2

The molecules in the small sample are bombarded with

Answer 2

high energy electrons which can cause the molecule to lose an electron

Question 3

The molecules in the small sample are bombarded with high energy electrons which can cause the molecule to lose an electron

This results in the formation of a

Answer 3

positively charged molecular ion with one unpaired electron
One of the electrons in the pair has been removed by the beam of electrons

Question 4

The molecular ion can further fragment to form

Answer 4

new ions, molecules, and radicals

Mass spectrometry only detects positively charged ions

Question 5

These fragmented ions are accelerated by an electric field
Based on their mass (m) to charge (z) ratio, the ion fragments are then separated by..

Answer 5

deflecting them into the detector

Question 6

Most ions will only gain a charge of 1+ and therefore a ion with mass 12 and charge 1+ will have an m/z value of 12

It is, however, possible for a greater charge to occur. For example, an ion with mass 16 and charge 2+ will have a m/z value of …………

Answer 6

8

Question 7

The smaller and more positively charged fragment ions will be detected first as they will get deflected the most and are more attracted to the negative pole of the magnet
Each fragment corresponds to a specific peak with a particular m/z value in the mass spectrum
The base peak is the peak corresponding to the most

Answer 7

abundant ion

Question 8

56Fe3+ has a smaller m/z ratio and will therefore be deflected more.
It also has the largest positive charge and will be more attracted to the negative pole of the magnet within the mass spectrometer.

what is its m/e or m/z value

Answer 8

19

Question 9

A small m/z value corresponds to fragments that are either small or have a high positive charge or a combination of both.