e-mail: dweis@eos.ubc.ca
phone / tél.: 1-604-822.1697
mobile: 778-386.4466

Analytical Developments and High-Precision Characterization of Reference Materials

The instruments housed at the Pacific Centre for Isotopic and Geochemical Research (PCIGR) have become critical to the advancement of research in geochemical, environmental, and medical fields. The highly sensitive nature of these analytical instruments requires that careful assessment of the accuracy and significance be attached to the results. For example, how well do we know the absolute values of reference materials? What are the matrix effects? Such questions and more must be asked when developing new analytical schemes.

nu tims
Nu TIMS (thermal ionization mass spectrometer)

Under Dominique’s guidance, the precision on Nd, Hf and Pb isotopic analyses is significantly better than 100 ppm (0.01%). PCIGR has established a high-precision database of reference materials, from felsic to ultramafic compositions to synthetic solutions, together with quality control protocols to monitor accuracy and precision (Weis et al., 2005, 2006 and 2007). The role of leaching (Nobre-Silva et al., 2009, 2010), mineralogy (Hanano et al., 2009) and matrix effects (Barling and Weis, 2008, 2012) on the precision and accuracy of multicollector-ICP-MS analyses for both radiogenic and heavy stable isotopes have been thoroughly investigated.

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143Nd/144Nd variations throughout the acid leaching procedure for basalts from Mauna Loa (upper left), Mauna Kea (lower left), Mont Crozier (upper right), and Northern Kerguelen Plateau (lower right) (Nobre Silva et al., 2010).
Backscattered electron micrographs and qualitative energy-dispersive spectra from regions of basalt sample J2-019-04 (Mauna Loa, Hawaii). cpx: clinopyroxene, ol: olivine. plan: plagioclase. (Hanano et al., 2009).

The results provide a solid reference basis for the scientific community and influence how researchers conduct their sample preparation and instrumental analyses. Our work on matrix effects (Barling and Weis, 2008, 2012), one of the first of its kind for isotopic ratios, has had a significant impact in particular.

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With the introduction of the new instruments in nUBC, and an extension of the PCIGR’s analytical pool, we have designed new experiments, for example to understand the effect of oxide formation on instrumental mass bias. Also, in collaboration with Nu Instruments engineers through a research and development partnership, we are looking to improve the limits of sensitivity of the instruments.

 Image Gallery:

Further Reading:

Fourny, A. et al. (2020) Testing for Pb isotopic differences between minerals in the Kiglapait layered intrusion by LA-ICP-MS. Chemical Geology, 537: 119475.

Bilenker, L.D. et al. (2018) The application of stable Fe isotopes to magmatic sulfide systems: constraints on the Fe isotope composition of magmatic pyrrhotite. Economic Geology, 113: 1181–1192.

Grasse, P. et al. (2017) GEOTRACES inter-calibration of the stable silicon isotope composition of dissolved silicic acid in seawater. Journal of Analytical Atomic Spectrometry, 32(3): 562–578.

Fourny, A. et al. (2016) Comprehensive Pb-Sr-Nd-Hf isotopic, trace element, and mineralogical characterization of mafic to ultramafic rock reference materials. Geochem. Geophys. Geosyst., 17: 739–773.

Schudel, G. et al. (2015) Trace element characterisation of USGS reference materials by HR-ICP-MS and Q-ICP-MS. Chemical Geology, 410: 223–236.

Skierszkan, E.K. et al. (2015) A practical guide for the design and implementation of the double-spike technique for precise determination of molybdenum isotope compositions of environmental samples. Analytical and Bioanalytical Chemistry, 407: 1925–1935.

Morisset, C.-E. et al. (2014) Methodology and application of Hafnium isotopes in ilmenite and rutile by MC-ICP-MS. Geostandards and Geoanalytical Research, 38: 159–176.

Abouchami, W. et al. (2013) A common reference material for cadmium isotope studies – NIST SRM 3108 Cd. Geostandards and Geoanalytical Research, 37: 5–17.

Barling, J. and Weis, D. (2012) An isotopic perspective on mass bias and matrix effects in an argon plasma using multi-collector inductively-coupled-plasma mass spectrometry. Journal of Analytical Atomic Spectrometry, 27: 653–662.

Jochum, K.P. et al. (2011) GSD-1G and MPI-DING reference glasses for in situ and bulk isotopic determination. Geostandards and Geoanalytical Research, 35: 193–226.

Nobre Silva, I.G. et al. (2010) Effects of acid leaching on the Sr-Nd-Hf isotopic compositions of ocean island basalts. Geochem., Geophys., Geosys., 11 (9).

Shiel, A.E. et al. (2010) Evaluation of zinc, cadmium and lead isotope fractionation during smelting and refining. Science of the Total Environment, 408: 2357–2368.

Nobre Silva, I.G. et al. (2009) Leaching systematics and matrix elimination for the determination of high‐precision Pb isotope compositions of ocean island basalts. Geochem., Geophys., Geosys., 10 (8).

Hanano, D. et al. (2009) Alteration mineralogy and the effect of acid-leaching on the Pb-isotope systematics of ocean-island basalts. American Mineralogist, 94: 17–26.

Shiel, A.E. et al. (2009) Matrix effects on the multi-collector inductively coupled plasma mass spectrometric analysis of high-precision cadmium and zinc isotope ratios. Analytica Chimica Acta, 633: 29–37.

Barling, J. and Weis, D. (2008) The influence of non-spectral matrix effects on the accuracy of Pb isotope ratio measurement by MC-ICP-MS. Implications for the external normalization method of instrumental mass bias correction. Journal of Analytical Atomic Spectrometry, 23: 1017–1025.