LC-MS: liquid chromatography–mass spectrometry basics

LC-MS couples a liquid chromatograph (which separates compounds) with a mass spectrometer (which identifies and quantifies them by mass-to-charge ratio). It is the backbone of modern bioanalysis, metabolomics and pharma QC.

How it fits together

The LC delivers separated analytes to an ionisation source — usually electrospray (ESI) or atmospheric-pressure chemical ionisation (APCI). Ions enter the mass analyser (quadrupole, time-of-flight, or Orbitrap) and are detected.

• Triple quadrupole: targeted quantitation, very low detection limits.
• Q-TOF / Orbitrap: high-resolution accurate mass for unknown identification.

Sensitivity and specificity far exceed UV detection, at higher instrument and maintenance cost.