School of Engineering and Science - Jacobs University

1.50 IF-G (n=2)
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 15. Accuracy estimation for ICPMS analysis of iron-formation IF-G, 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. Data for Sc not reported due to high IQL, and Nb not reported due to significant
FeCl interference. Reasons for poor observed Ti accuracy are considered to be similar to those proposed
for FeR-4 (see text for details). Lower JUB concentrations for Hf, Ta, Pb, and Th are not considered
anomalous, as it is likely that these elements are present at concentrations lower than originally reported
for IF-G, an observation supported by the data of Dulski et al. (2001) and Bohlar et al. (2004).
performed using the current 32 element ICPMS analysis (see App. 1). Results from
these analyses are presented in Figure 15, and JUB data for 23 of 32 elements are
between 90–100% of the average reference values. Data for Sc and Nb are not shown,
as Sc concentrations in IF-G (~0.3 mg/kg) are below the IQL for Sc (Fig. 4), and
literature Nb concentrations of ~0.1 mg/kg are significantly lower than the predicted
FeCl interferences on 93 Nb of ~0.6 mg/kg (Apps. 1 and 2).
The apparent poor accuracy of the JUB determination for Ti is considered to
arise from reasons similar to those proposed for Ti determinations in FeR-4, i.e., a
combination of low concentration (84 mg/kg) and analytical methodology for
determination of the reference values (e.g., sample fusion and XRF analyses). The
wide discrepancy observed for the Hf, Ta, Pb, and Th data of this study is primarily
due to the inclusion of values from Govindaraju (1994) when calculating the
reference average for these elements. Compared to more recent ICPMS analyses by
Dulski (2001) and Bohlar et al. (2004), JUB data for these elements are quite
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