Mass spectrometry: how it works

A mass spectrometer measures the mass-to-charge ratio (m/z) of ionised molecules to determine molecular weight, structure and abundance.

Three stages

• Ionisation: EI, ESI, APCI or MALDI converts neutral molecules to ions.
• Mass analysis: quadrupole, ion trap, time-of-flight or Orbitrap separates ions by m/z.
• Detection: an electron multiplier or image-current detector records ion intensity.

Why it matters

Mass spectrometry provides both qualitative identification (what is in the sample) and quantitative measurement (how much), often at trace levels, making it indispensable across pharma, clinical, environmental and forensic labs.