LA-ICP-MS

Laser Ablation ICP-MS Laboratory

Purchased with the support of SNSF, Société Académique de Genève, Fondation Ernst et Lucie Schmidheiny, Fondation Ernest Boninchi and the University of Geneva.

The LA-ICP-MS consists of an ESL (former NWR) 193 HE laser ablation system coupled with an Agilent 8900 triple quadrupole ICP-MS. Its configuration has been optimized for the analysis of silicate melt and fluid inclusions in minerals, but it performs equally well in many other typical application areas of LA-ICP-MS.

Performance Highlights:

Laser Ablation System:

  • Large format Coherent Compex 102 laser excimer laser source
  • Attainable energy densities on sample surface 1 – >50 J/cm2, controlled ablation of quartz and fluorite
  • Excellent sample viewing optics – 1-2 µm-sized features are resolvable
  • Highly flexible aperture system – circular beam sizes from 1 – 300 µm in single micron steps, freely rotatable rectangular beams with independently variable a and b dimensions in single micron steps
  • Two-volume ablation cell with 10 X 10 cm useful area and rapid-flushout, well-adaptable to any sample type/shape
  • Sophisticated software: easy orientation by additional wide angle camera or via cross-coordination with imported sample images, programmable patterns, ImageLock feature yields better than 1 µm long-term stage position accuracy, communication plug-in for Agilent ICP-MS (see also www.icpmslasers.com)

ICP-MS:

  • Very high sensitivities, 20 – 25 kcps/ppm on mid and heavy masses on NIST610 glass (while using 40 µm circular beam, 10 Hz, 7 J/cm2 energy density on sample, tuned to ThO/Th < 0.3%, Mass 21/ 42 Ca < 0.3% and U/Th=1.00 – 1.05, in single quad, no gas mode)
  • Practically zero backgrounds on most mid and heavy masses, which coupled with the high sensitivities leads to very low detection limits (see Figure below)
  • Being coupled with the excimer laser ablation system, minor matrix dependence of relative sensitivity factors (i.e. largely matrix independent calibration, see Figures below)
  • Equipped with 4 collision/reaction gas lines (He, H2, O2, N2O and NH3 gases are available)
  • Usage optimized to keep the instrument clean and maintain low detection limits for Au, platinum group elements, S, Cl, Br, I, B and Li.
  • Triple quadrupole design facilitates the exploration of new application areas such as in situ Sr isotope ratio analysis even in Rb-rich materials or the analysis of S in the form of oxides to eliminate any oxygen-based interferences (e.g. 16O16O, 18O16O)

Laboratory Environment:

  • the instrument is housed in cleanroom environment
  • we use 6.0 purity Helium and ultra high-purity gas delivery lines for the lowest gas blanks on volatile elements
  • NIST610, NIST612, NIST617, GSE-1g, GSD-1g glasses, an in-house S and halogen doped multielement andesite glass standard, JCP-1-NP and ECRM752-1-NP carbonate pressed nano powder reference materials available
  • the instrument shares a room with a Neptune Plus MC-ICP-MS, to which the laser ablation system can also be connected, split-stream application is under development
Typical matrix (in)dependence of LA-ICP-MS analysis in the laboratory. The diagram shows the results of the USGS GSD-1g basaltic glass analysis with the felsic NIST SRM610 glass being used as external standard. The results show that the nominal and the measured concentrations are consistent with each other within ±10 relative % despite the large difference in composition and color between the two glasses. The internal standard used for quantification was the known total of major element oxides. The red error bars correspond to the uncertainty of the nominal element concentrations in the GSD-1g (based on GeoRem preferred values).

The accuracy of major element oxide concentration determination by using LA-ICP-MS. For quantification, major element oxide totals were used as internal standard and the USGS GSD-1g glass as external standard. Smithsonian series mineral standards were measured as unknown and the deviations from nominal concentrations are shown as relative percentage.
Typical limits of detection at 3 sigma definition obtained on the GSD-1g glass with 40 micron diameter circular beam, 10 Hz repetition rate and 7 J/cm2 laser energy density on the sample surface.