Multi-Collector Mass Spectrometry

The laboratory performs analyses of stable isotopes (Li, Mg, Sr, Pb, Cr, Zn, Cd, Mo, Cu, Lu-Hf, Ni, Si, Fe). The laboratory includes a specialized Ultratrace Laboratory with controlled sterility, in which samples are prepared for analysis.

The laboratory provides services mainly to internal staff members involved in research projects, and cooperation with science and education departments can also be arranged. Selected isotope analyses can also be performed as commercial contracts.

Range of Services

The laboratory analyzes isotope ratios in natural materials. The range of selected analyses is specified in the Laboratory Price list.

Equipment

• Thermo Scientific Neptune Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC ICP MS)

Method Description

Argon plasma (ICP module, see diagramme) is the core and primary source for ionization of elements in this instrument. The argon plasma is sustained with a high radio-frequency magnetic field after cascade spark discharge. Due to its high ionization potential, argon plasma can ionize most elements in the periodic table.

The sample, which is introduced into the plasma as an aerosol or in gaseous form, is first completely dried, atomized, excited and ionized in the plasma as a result of free-electron bombardment. The ions from the plasma are sampled via a multi-stage interface region into a very high vacuum environment (<2.5 x 10^-7 mbar), in order to sustain the ionized state of the elements.

The ion beam, whose composition duplicates the sample composition, then passes through ion optics, where its shape and ion properties such as axial kinetic energy and so forth are optimized (ESA module, see diagramme).

A mass filter system is a device capable of filtering only a specific mass fraction from an ion beam by means of an electric and magnetic field. The ions pass through the mass filter (i.e., the magnet) along a partially circular path, which causes them to be out of focus relative to the beam axis due to the mass of the isotopes and their charge. An array of moveable detectors is located behind the mass filter, enabling each to detect a specific mass fraction - isotope (multi-collector module). A given isotope ratio is obtained simultaneously from the ratio of the signal on any two detectors.