Mass Spectrometer

Question 1

Vaporization

Answer 1

The sample to be analyzed is heated and vaporized and passed into an evacuated tube. This results in particles that are separate from one another.

Question 2

Ionization

Answer 2

The atoms or molecules are then bombarded by a stream of high energy electrons and one or more electrons are knocked off each atom or molecule. This results in ions with, most commonly, a 1+ charge, but sometimes with a 2+ charge.

Question 3

Acceleration

Answer 3

The positively charged ions are accelerated along the tube by attraction to negatively charged plates and the ions pass through slits that control the direction and velocity of their motion.

Question 4

Deflection

Answer 4

The stream of ions is passed into a very strong magnetic field, which deflects the ions through a curved path. If the size of the magnetic field is fixed, a light ion will be deflected more than a heavy ion and a 2+ ion will be deflected more than a 1+ ion of the same mass

Question 5

What does deflection depend on?

Answer 5

The deflection of the ions depends on the mass/charge (m/z) ratio.

Question 6

Detection

Answer 6

The ions are detected electronically by a device that measures both the location and the number of particles that collide with it.

Question 7

Recording (The percentage abundance)

Answer 7

different isotopes is recorded as a graph called a mass spectrum. A peak is produced in the mass spectrum for each isotope (ion with a particular mass and charge).

Question 8

What is the x-axis and y-axis of a mass spectrum graph for the isotopes that were run through a mass spectrometer?

Answer 8

y-axis: percent abundance
x-axis: mass/charge
(m/z)