School of Engineering and Science - Jacobs University

1.50
HF-HClO 4
carbonate (HNO 3
)
1.25
JUB / reference average
1.00
0.75
0.50
0.25
0.00
Sc Ti Co Ni Rb Sr Y Zr Nb Mo Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Pb Th U
Figure 20. Comparison of analytical accuracy relative to average reference values for both HF-HClO 4
and carbonate (HNO 3 ) decompositions of the JDo-1 dolomite. Based upon similar results for the two
decomposition methods, Sr, Y, the REE, W, Th, and U are considered to be quantifiable using the
carbonate decomposition method. Additionally, note the excellent results for Ni determined from the
carbonate decomposition method, which were calculated using the 62 Ni isotope. Elements likely to be
hosted in refractory aluminosilicate phases that resist complete dissolution using the carbonate
decomposition include Ti, Rb, Zr, Nb, Cs, Hf, and Ta.
refractory mineral phases. If that is the case, then these refractory minerals may not be
homogenously distributed within the JDo-1 powder, offering a possible explanation
for the wide variation in reported concentrations for incompatible elements.
Compared to the HF-HClO 4 decomposition method the carbonate
decomposition method is not expected to completely dissolve all mineral phases (e.g.,
aluminosilicates), and data for JDo-1 obtained using the two different decomposition
methods are presented in Figure 20. Regarding the carbonate decomposition of JDo-1,
and many other carbonate samples as well, a black residue is commonly filtered out of
the sample solution, and this residue is presumed to be refractory organic carbon. The
black solid retained during the filtering step does not appear to be of significance for
the determination of Ni, Sr, Y, the REE, W, Th, and U, and it is concluded that these
elements are hosted primarily by carbonate minerals, and therefore are quantifiable
using the carbonate decomposition method. The accurate quantification of Ni using
the carbonate method is notable, as this is only possible in an HNO 3 acid matrix and
by monitoring the 62 Ni isotope. Unlike 60 Ni, which is generally not suitable for Ni
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