he classical 147Sm−143Nd radiogenic isotopic system has
been extensively used in geochemistry and cosmochem-
istry as a powerful geochemical tracer or chronometer since the
1970s.1,2 High precision ratios of 143Nd/144Nd and 147Sm/144Nd are prerequisites for dating and tracing purposes.
pic
Usually, reproducibility of ≤0.003% for 143Nd/144Nd ratio and
≤1% for 147Sm/144Nd ratio is required in geochronological and
geochemical studies. Isotope dilution mass spectrometry
(IDMS) technique is considered to be a primary method that
can produce excellent accuracy and precision.3,4 Isotope
dilution thermal ionization mass spectrometry (ID-TIMS)
technique5−11 and isotope dilution multiple-collector induc-
tively coupled plasma mass spectrometry (ID-MC-ICP-MS)
technique12−15 have been used for achieving accurate and
precise results for Sm−Nd.
MC-ICP-MS offers high efficiency for precise isotopic ratio
measurements with high sample throughputs.12−16 When a
laser ablation is coupled with MC-ICP-MS, in situ analysis of
tiny mineral grains with high concentrations of Sm−Nd (>200
ppm at least), such as apatite, monazite, and perovskite can be
done.17−20 However, compared to TIMS, the cost of the MC-
ICP-MS instrument and operation is higher. In addition, MC-
ICP-MS suffers much larger mass bias and more complicated
isobaric interferences of oxides and/or argides.21 On the other
hand, TIMS generally offers better sensitivity and precision for
Sm−Nd measurements. For example, the external precision of 143Nd/144Nd in a Nd standard (Ames) reached the level of ±2
ppm using TIMS.22 The excellent precision in Sm−Nd data
was obtained using TIMS even at very small sample size down
to 1 ng.10,11,23 Hence, both Sm−Nd isotopic compositions and
elemental contents are traditionally performed by TIMS,
considered as the benchmark technique.10,22,24
To achieve accurate Sm and Nd isotopic data in geological
samples, all isobaric interferences (144Sm on 144Nd, 148Sm on 148Nd, and 150Sm on 150Nd) need to be eliminated. Tradition-
ally, after sample digestion and sample-spike (149Sm−150Nd)
equilibration, Sm and Nd fractions are completely separated
from the matrix solutions using the classical two-step cation
exchange chromatography technique before TIMS measure-
ments.5−10,14,15,22−29 After the solution dried, the purified Sm
and Nd fractions from spiked samp
LIGHT
Be the first to boost its visibility.
