Mass spectrometer
A mass spectrometer is an instrument that separates atoms or molecules by mass to measure isotopes and elements.
A mass spectrometer turns a sample into charged particles, called ions, and sends them through electric or magnetic fields. Lighter ions are deflected more than heavier ones, so the instrument separates them by mass and counts each kind. This allows scientists to measure isotope ratios with astonishing precision, sometimes to a few parts per million.
There are many types. Thermal ionisation mass spectrometers heat a dried sample on a metal filament. Inductively coupled plasma mass spectrometers, often called ICP-MS, use a plasma at several thousand degrees. Noble gas mass spectrometers measure tiny amounts of helium, neon, argon and xenon released by heating. Ion probes analyse spots just micrometres across.
Almost all meteorite dating and isotope fingerprinting relies on mass spectrometry. Measurements of oxygen isotopes, lead–lead ages, cosmic-ray exposure ages and presolar grain compositions would be impossible without it. The instruments are housed in clean laboratories to avoid contamination by dust and air.
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