Analytical method · Identification
Mass Spectrometry (MS)
An analytical technique that ionises molecules and measures them by mass-to-charge ratio.
What is it?
A sample is ionised and the resulting ions are separated and measured according to their mass-to-charge ratio, producing a spectrum of detected masses.
What does it measure?
Ion abundance across mass-to-charge values, from which an observed mass can be determined.
What type of result does it produce?
A mass spectrum; an observed mass compared against a theoretical mass supports identity.
What can the result support?
- Identity evidence when observed mass matches theoretical mass within tolerance
- Detection of mass differences that separation alone cannot reveal
What can it not establish?
- Purity as a standalone composition figure
- Biological activity or fitness for use
What variables affect the result?
- Ionisation method
- Mass analyser type and resolution
- Calibration and tolerance
- Sample preparation
Example output
An observed mass reported alongside the theoretical mass for the intended sequence, within a stated tolerance.
Common interpretation mistake
Assuming a matching mass alone fully characterises a material; mass is strong identity evidence but does not describe composition.