School of Engineering and Science - Jacobs University

1.50 SCo-1 (n=4)
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 16. Accuracy estimation for ICPMS analysis of shale SCo-1, where n equals the number of
separate HF-HClO 4 sample decompositions and ICPMS analyses in 0.5 M HCl. Grey bars represent
variability in the calculated ratio that is due solely to uncertainty in the reference average. Vertical lines
represent the variability in the calculated ratio due to the uncertainty of the JUB data, and all data are
presented in App. 1. The triangles for Sc, Ti, Co, and Ni represent average JUB data that excludes a
single analysis that determined anomalously high values for these four elements, and when the
‘anomalous’ data are not considered the JUB averages more closely match the reference values for Sc,
Ti, Co, and Ni.
to a single JUB analysis of SCo-1 that determined much higher concentrations for
these elements, and when these ‘anomalous’ data are not considered (see Fig. 16), the
measured concentrations for 30 of 32 analyzed elements are between 90–110% of the
reference value.
Potential major element interferences on trace metal determinations in SCo-1
would include 27 Al 35 Cl on 62 Ni, and FeCl on 93 Nb (Table 4). The impact of Alchloride
interferences on 62 Ni is significant enough that it is recommended that 62 Ni
not be used for Ni determinations in shales (or sediments) that contain more that a
few percent Al 2 O 3 and that are diluted in HCl (see App. 2). Note that the Ni data
presented in App. 1 and Fig. 16 reflect concentrations for SCo-1 that were determined
solely by monitoring of 60 Ni. As for Nb, the presence of ~5% Fe 2 O 3 in SCo-1 would
be predicted to increase Nb concentrations by roughly 0.1 mg/kg, which is
insignificant when compared to the SCo-1 reference Nb value of 11.9 mg/kg. It is
therefore concluded that Fe 2 O 3 concentrations in shales (or sediments) of 3-7% are
40