MYTUTOR SUBJECT ANSWERS

486 views

How do mass spectrometers work?

A mass spectrometer is a piece of lab equipment used to measure the relative atomic masses of atoms and molecules. It is widely used to identify substances in the lab.

The process is often automated and requires a number of sequential steps that take places in a specially built vacuum chamber. 

1. The sample is injected either as a gas or vapour

2. An electron gun creates a beam of electrons which collide with the sample atoms and, by removing electrons, ionise them. This creates cations which generally have a 1+ charge; about 5% gain a 2+ charge. Molecules often fragment producing a range of molecules with different masses.

3. A series of negatively charged plates with a small gap between accelerate the cations. This creates a beam of cations in which the lighter cations move faster than the heavier ones.

4. A magnetic field applied perpendicular to the direction of travel causes the beam to be deflected. The amount of deflection is dependent on the charge-to-mass ratio (m/z); heavier ions are deflected less than lighter ones. In this way the sample beam is separated by mass. 

5. The magnetic field is gradually adjusted so that ions of increasing mass strike a detector one after another. As the cations strike they remove electrons from the detector, this results in an electric current proportional to the abundance of the specific ion. 

This data is fed into a computer which creates a mass spectrum; a graph of m/z against relative abundance. By comparing the peaks to known sample graphs the identity of the original sample can be ascertained. 

George B. A Level Chemistry tutor, GCSE Science tutor, GCSE Biology t...

2 years ago

Answered by George, an A Level Chemistry tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

97 SUBJECT SPECIALISTS

£20 /hr

Georgina R.

Degree: Chemistry (Masters) - Bristol University

Subjects offered:Chemistry, Physics+ 1 more

Chemistry
Physics
Maths

“I am a motivated and hard-working student with 3 years of tutoring experience. I am a clear and concise tutor, who believes in a patient approach to learning.”

MyTutor guarantee

£20 /hr

Laura K.

Degree: Chemical Engineering (Masters) - Bath University

Subjects offered:Chemistry, Science+ 3 more

Chemistry
Science
Physics
Maths
Further Mathematics

“Hey there! I am Laura and I am currently studying Chemical Engineering at University of Bath. I am really passionate about Science and I am willing to share my knowledge through tutoring you. My passion and expertise in science can be...”

£24 /hr

Joe M.

Degree: Biology (Bachelors) - Durham University

Subjects offered:Chemistry, Science+ 2 more

Chemistry
Science
Maths
Biology

“Second year Biology student tutoring science and maths in a relaxed and friendly environment”

About the author

George B.

Currently unavailable: for regular students

Degree: Chemistry (Masters) - Oxford, Jesus College University

Subjects offered:Chemistry, Science+ 3 more

Chemistry
Science
Physics
Maths
Biology

“About Me: As a second year chemist at Oxford University I naturally have a love for anything and everything science. Science can be challenging at times however, with the right approach, it can be anengaging and exciting subject. I ho...”

You may also like...

Posts by George

How can aldehydes and ketones be distinguished?

How do mass spectrometers work?

What's the difference between speed and velocity?

Other A Level Chemistry questions

What is a chiral carbon?

What is entropy?

Describe and explain some of the factors that affect polymer properties.

What is clonal selection?

View A Level Chemistry tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok