Meaning and Working Principle
Mass Spectrometry (MS) is an analytical technique used to identify chemical substances and measure their amount by analysing the mass of their charged particles.
A mass spectrometer broadly works in three stages:
- the sample is converted into charged particles called ions;
- these ions are separated according to their mass-to-charge ratio (m/z);
- a detector records the ions and produces a mass spectrum.
The mass spectrum acts like a chemical fingerprint, helping scientists determine what molecules are present and in what quantity.
Main Components and Types
A mass spectrometer usually contains:
- Ion source: converts molecules into charged ions.
- Mass analyser: separates ions according to mass-to-charge ratio.
- Detector: measures the ions reaching it.
- Computer system: converts the signal into a readable spectrum.
Common ionisation methods include:
- Electrospray Ionisation (ESI): useful for proteins and biological molecules.
- MALDI: commonly used for large biomolecules.
- Electron Ionisation: widely used for smaller volatile compounds.
Mass spectrometry is often combined with separation techniques such as:
- Gas Chromatography–Mass Spectrometry (GC-MS)
- Liquid Chromatography–Mass Spectrometry (LC-MS)
These combinations allow complex mixtures to be separated before individual compounds are identified.
Applications and Significance
Mass spectrometry has applications across:
- metabolomics and proteomics;
- pharmaceutical research and drug testing;
- forensic science and toxicology;
- detection of pesticides and contaminants;
- food-quality testing;
- environmental monitoring;
- isotope analysis;
- clinical diagnostics;
- space and planetary science.
For example, in metabolomics, mass spectrometry can detect hundreds or thousands of small molecules in blood, urine or tissue and compare their levels between healthy and diseased individuals.
Its major advantages are high sensitivity, high accuracy and the ability to detect very small quantities of substances.
However, results depend on proper sample preparation, instrument calibration and expert interpretation, and some molecules may require specialised ionisation techniques.
Mass spectrometry is therefore essentially a high-precision molecular identification tool, capable of revealing the composition of highly complex biological, chemical and environmental samples.
