Evelyn Freres

PhD Geological Sciences

MAGNET Trainee

EOS-Main 305

What are the limitations to correcting isotopic ratios?

My research at UBC, as a Ph.D. student and a MAGNET Trainee is focused on improving precision and accuracy in Multi Collector-Inductively Coupled Plasma-Mass Spectrometry.

MC-ICP-MS instruments are able to produce high-precision, high-accuracy ratio measurements for several of isotopic systems. Scientists from different areas use these measurements for a wide range of applications, such as fingerprints of the source of geologic samples, tracers for natural/anthropogenic processes that cause mass fractionation, and cosmo- and geochronology. Each of these applications requires various degrees of precision, making the constant and dynamic improvement of isotopic measurements paramount to several fields of science.
The isotopic ratios measured using MC-ICP-MS, however, are always biased from their “true” value due to mass fractionation caused by processes inherent to this technique. Generally, fractionation laws, double spiking or/and standard-sample bracketing (SSB) can correct for these discrepancies. However, some other minor sources of mass bias cannot be resolved in the same way.

My interest is in constraining and characterising different sources of mass fractionation that are introduced by this instrument, and that cannot be corrected for using traditional methods. As the outcome of this research, I intend on developing a set of analytical methods to correct, minimise, or overcome the impact of these phenomena on MC-ICP-MS measurements. 

Teaching Assistantships:

August 2009 - July 2012  Teaching Assistant at the Federal University of Rio de Janeiro for the Department of Inorganic Chemistry for the following courses: Experimental General Chemistry II, Experimental Inorganic Chemistry I, and Experimental Inorganic Chemistry II

August 2012 - December 2012  Teaching Assistant at the Federal University of Rio de Janeiro for the Department of Physical-Chemistry for the following course: Experimental Physical-Chemistry I

September 2014 - Present  Teaching Assistant at the University of British Columbia for the Department of Earth, Ocean and Atmospheric Sciences for the following courses: EOSC 111 – Laboratory Exploration of the Planet Earth (2014-2015), EOSC 110 – The Solid Earth: A Dynamic Planet (2015), EOSC 340 – Global Climate Change (2016)