Thermal ionization mass spectrometry

A chemically purified liquid sample is placed on a metal filament which is then heated to evaporate the solvent.

The ions gain velocity by an electrical potential gradient and are focused into a beam by electrostatic lenses.

An activator represses the evaporation of the desired element and can either increase or decrease the ionization potential of the filament.

The evaporation process is usually conducted at relatively low temperatures in exchange for long-lasting signals and minor isotopic fractionation.

[6] The ions emitted have low spatial and energetic spread which makes a single-focusing magnetic sector mass analyzer or quadrupoles suitable.

Following the trend of decreasing ionization energy, elements located towards the bottom left of the periodic table are viable for TIMS.

In addition, the high electron affinity seen towards the upper right of the periodic table makes these nonmetals excellent candidates.

[7][8] Quantitative isotope ratio techniques include isotope dilution thermal ionization mass spectrometry (ID-TIMS) [9] and chemical abrasion thermal ionization mass spectrometry (CA-TIMS).

Inductively coupled plasma-quadrupole mass spectrometers allows for an even higher precision of detecting the change of isotopic ratios by radioactive decay.

Thermal ionization mass spectrometer. Vacuum chamber on the left, electromagnet in the center, and ions detector on the right are visible.
Two filaments in thermal ionization mass spectrometry