School of Engineering and Science - Jacobs University

Figure 2. Diagram showing preparation of multi-element standards used for ICPMS external calibration
and internal standardization. Note that immediately prior to an ICPMS analysis, all solutions receive 10
μg/kg of the Ru, Re, Bi internal standard (see text for details). Trace amounts of HF (0.05 M) are used
to stabilize high field strength elements (Ti, Zr, Nb, Ta, etc.).
between samples and calibration standards, as the standards used for calibration are
incorporated directly into aliquots of the sample solution itself. The greatest drawback
to the standard addition method is that it does not lend itself to multi-element
analyses, as it is most accurate when the spike concentrations for an individual
element are similar to the unknown concentration in the sample. For geological
samples, in which concentrations of trace metals routinely range over three orders of
magnitude, this would necessitate the creation of calibration standards containing 32
potentially different, customized element concentrations, which assumes some preexisting
knowledge of these elemental concentrations in the unknown sample.
Combined with the fact that every sample would require at least triple the ICPMS
analysis time, the standard addition calibration method is generally not recommended
for routine, multi-element ICPMS analyses of geological samples.
However, the external standard calibration method suffers from the
aforementioned ‘matrix effects’. These matrix effects are particularly troublesome for
analyses of geological materials which contain significant amounts of dissolved solids
at typical ICPMS dilution factors. For example, an iron-formation with 90% Fe 2 O 3
that is diluted 1000x would produce a solution containing more than 600 ppm Fe, and
this is generally the maximum dilution suitable for pure iron-formation samples. High
dissolved metal concentrations tend to suppress ICPMS instrument sensitivity in a
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