Inductively coupled plasma (ICP) ion source is maintained by the resistive heating of an atmospheric pressure argon plasma by eddy currents induced in it through inductive coupling. Owing to its operation at atmospheric pressure, this source is very flexible with respect to the sample introduction process : laser ablation, solution nebulisation, chemical vapour generation, electrothermal vaporisation and liquid chromatography are some of the most frequently used sample introduction techniques that can be coupled to the ICP.
- Efficient ion source : most elements of the periodic table are >90% ionised during the introduction of the sample in the ICP.
- High analytical sensitivity: most elements of the periodic table down to a (sub)ppt-level in liquid samples and down to a (sub)ppb level in solids (depending on the sample introduction rate and background level).
- High sample throughput
- Little sample preparation compared to the alternative techniques, such as SIMS.
For in-situ measurements, ICP mass spectrometers are typically coupled to laser ablation facilities. A laser beam of 20 to 150 µm in size is focussed onto a solid sample, which is ablated in a helium atmosphere. The ablated material is then directed to the ICP, where it is melted, vaporised, atomised and ionised. Although the inefficient ion extraction from the ICP through the spectrometer interface and into the spectrometer ion channel, kept under vacuum, is responsible for huge ion losses, the fraction of ions actually extracted from the ICP is sufficient for many applications. And where the highest possible ion extraction efficiency is needed, SIMS facilities are used : they operate under vacuum and have a better ion extraction efficiency, allowing to reach the same sensitivity as with LA-ICPMS for a slower sample introduction rate (smaller beam size, better spatial resolution).
The laboratory has two ICP-MS facilities:
Quadrupole spectrometer Agilent 7700
This instrument can be interfaced to a GeoLas 200M ArF excimer ablation system or used alone for the analysis of liquid samples. It is used in applications that do not require the lowest possible detection limit (e.g. glass discs and minerals, natural and underground waters).
Sector-field spectrometer Element XR
This instrument can be interfaced to a NewWave UP-193 ArF excimer ablation system or used alone (liquid samples). It is applied for analysis of very low element concentrations in minerals (olivine, orthopyroxene, mica and feldspars, and particularly for the U-Pb dating of zircons).
The laboratory has a wide experience in the analysis of geological samples and also carries out analyses for chemical and technical research institutions, as well as for commercial entities.
More information on this recent ICP-MS review :
Ulianov A., Müntener O., Schaltegger U., 2014. The ICPMS signal as a Poisson process: a review of basic concepts. Journal of Analytical Atomic Spectrometry. DOI: 10.1039/C4JA00319E
Head of the lab
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+41 21 692 44 39