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 vapor 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)ng/g 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 three ICP-MS facilities:
Quadrupole spectrometer Agilent 7700x
This instrument can be interfaced to an UP-193FX 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
In the standard configuration, this sensitive instrument is interfaced to a RESOlution SE ArF excimer ablation system. It can also be used alone (liquid samples). It is applied for analysis of very low element contents in minerals (olivine, orthopyroxene, mica and feldspars), and particularly for the U-Pb dating of zircons.
Multiple Quadrupole spectrometer NexION 5000
This sensitive, fast-scanning, low-blank instrument can be linked to the RESOlution SE ArF excimer ablation system or used alone for the analysis of liquid samples. It is most commonly employed for the analysis of trace and ultra-trace elements in minerals, as well as for the combined analysis of trace elements and U/Pb ratios in zircons. In the four-quadrupole mode, it allows to eliminate ‘difficult’ spectral interferences without huge sensitivity losses typical of magnetic sector-field instruments run in the high-resolution regime.
Ar-F excimer ablation system RESOlution SE
The 193 nm Ar-F excimer ablation system RESOlution SE is our most recently acquired and most frequently used ablation system. It is equipped with a highly automated, 2-vol. ablation cell S155 that offers a number of advantages: 1) simple and efficient navigation; 2) low flicker and fixed-frequency signal noise; 3) absence of position effect; 4) minimal cross-talk and fast wash-out; 5) possibility to mount a number of samples at a time using an appropriate sample holder. Both spot- and raster-mode analysis is possible. Pre-programming of ablation sites and subsequent automatic acquisition of data is the commonest way to employ this system.
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 ICP-MS review:
Ulianov A., Müntener O., Schaltegger U., 2015. The ICPMS signal as a Poisson process: a review of basic concepts. Journal of Analytical Atomic Spectrometry. DOI: 10.1039/C4JA00319E
Prof. Othmar Müntener
Head of CASA facility and LA-ICP-MS lab
+41 (0)21 692 43 47
Dr. Alexey Ulianov
LA-ICP-MS lab Manager