International Journal of Analytical Mass Spectrometry and Chromatography, 2013, 1, 95-102
Published Online December 2013 (
Open Access IJAMSC
A Simple and Fast Separation Method of Fe Employing
Extraction Resin for Isotope Ra tio Determi nation by
Multicollector ICP-MS
Akio Makishima
The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry (PML), Institute for Study of the Earth’s Interior,
Okayama University, Misasa, Tottori, Japan
Received October 17, 2013; revised November 13, 2013; accepted December 16, 2013
Copyright © 2013 Akio Makishima. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A new, simple and fast separation method for Fe using an extraction chromatographic resin, Aliquat 336 (commercially
available as TEVA resin) has been developed. A one milliliter column containing 0.33 mL TEVA resin on 0.67 mL
CG-71C was used. Iron was adsorbed with 6 mol·L1 HCl + H2O2 on TEVA resin, and recovered with 2 mol·L1 HNO3.
The recovery yield and total blank were 93.5 ± 6.5% and 6 ng, respectively. The separation method is simple, and takes
<2 hours. For evaluation of the Fe separation, Fe isotope ratios were measured by a double-spike method employing
multicollector inductively coupled plasma source mass spectrometry (MC-ICP-MS) with repeatability of 0.06‰ (SD)
for the standard solution and ~0.05‰ for the silicate samples. Therefore, the column chemistry developed in this study
is a viable option for Fe isotope ratio measurement by MC-ICP-MS.
Keywords: Fe Separation; Fe Isotope Ratio; Multicollector Inductively Coupled Plasma Source Mass Spectrometry
1. Introduction
Trioctylmethylammonium chloride (Aliquat 336) works
as an anion exchanger, and is used in extraction chroma-
tography (commercially sold as TEVA resin) [1]. Yang
and Pin [2] and Grahek and Macefat [3] have tried to use
the TEVA resin for Fe separation. The eluent volumes of
60 mL for 1 mL of the TEVA resin and 120 mL for 3 g
(equates ~2.7 mL) TEVA resin were used, respectively.
However, these volumes are too mamy to handle; large
space is required and evaporation takes a long time. Re-
cently, Makishima and Nakamura [4] successfully puri-
fied Zn using a one milliliter column composed of 0.33
mL TEVA resin on 0.67 mL CG-71C resin. They used
the advantage of acid resistance of the TEVA resin [5],
namely, HNO3 was used in the final step to recover Zn
that was strongly adsorbed on the resin. Based on this
novel finding, it was noticed that the anionic character of
the TEVA resin could be applied to separation of Fe.
This study applies the TEVA resin for purification of Fe
for isotope ratio measurements using multicollector
(MC)-ICP-MS for the first time.
An advantage of the new TEVA resin column chemis-
try is that the whole column chemistry (from sample
loading to Fe collection) finishes <2 hours. Anion ex-
change resins, AG 1X8 or AG MP-1 employing Fe(III)
chloro complex are commonly used [6,7]. In a one milli-
liter of AG 1X8 column case, for example, the total
volume of 55 mL [7], was used from washing the column
to collection of Fe. Using an AG MP-1 column, total
elution volume for Fe was reduced to 22 mL [6].
For evaluation of column chemistry and mass spec-
trometry developed in this study, three USGS (the US
Geological Survey) standard silicate reference materials,
seven GSJ (the Geological Survey of Japan) standard
silicate reference materials and three carbonaceous chon-
drites of Orgueil, Murchison and Allende were used as
test samples. Then Fe isotope ratios were measured using
a double spike method [8-11] at high mass resolution by
MC-ICP-MS to show the validity of the method.
2. Experimental
2.1. Reagents
All experiments were performed in clean rooms and
clean benches with HEPA (High Efficiency Particulate
Air) filter in the Pheasant Memorial Laboratory (PML)
[12]. Water and HF were purified as described elsewhere
[12]. Hydrochloric acid was distilled by a Teflon-two-
bottle distiller [12]. TAMAPURE-AA-100 grade per-
chloric acid (Tama Chemicals Co., Ltd., Japan), electric
industry (EL) grade HNO3 and ultrapure hydrogen per-
oxide (Kanto Chemical Co. Inc., Japan) were used with-
out purification. Six mol·L1HCl with 0.05 % (v/v) H2O2
was prepared just before the column chemistry. For the
column calibration, two multi-element standard solutions
(Specpure, Nos. 42885 and 44270, Alfa Aesar, USA)
were used.
CAUTION: HF, HCl, HNO3, HClO4 and H2O2 are
highly corrosive and toxic. Inhalation and contact with
skin and eyes should be avoided. They should be handled
with protective glasses and gloves.
Iron standard metal, IRMM-014 was dissolved, and
finally diluted into 1 μg·mL1 with 0.5 mol·L1 HNO3
and used as the isotopic standard for MC-ICP-MS. TE-
VA extraction resin (100 - 150 μm, Eichrom Technolo-
gies, Inc., USA) and Amberchrom CG-71C (Rohm and
Haas, Co., USA) were soaked and stored in water. TEVA
resin and CG-71C were not reused.
2.2. Iron Double Spike
A 57Fe-58Fe double spike [10,11] was chosen. Iron iso-
topes of 57Fe and 58Fe, with enrichments of 86.06 and
73.51%, respectively, were purchased from Oak Ridge
National Laboratory (USA). Each spike was dissolved
and diluted with HNO3, then mixed and used as a Fe
double spike. Ideal isotopic abundances of the double
spike were 47.65 and 52.35% for 57Fe and 58Fe, respec-
tively [10], and the best sample: spike mole ratio is 55:45
[10]. Therefore, 1 μg sample Fe was mixed with 0.8 μg
double-spike. To keep this ratio, the Fe concentration in
the sample solution was determined before the spike ad-
dition by high-resolution ICP-MS [13].
2.3. Silicate Samples
Three USGS silicate reference materials, BHVO-1 (ba-
salt), AGV-1 (andesite) and PCC-1 (peridotite) and seven
GSJ silicate reference materials, JB-1, JB-2, JB-3 (ba-
salts), JA-1, JA-2, JA-3 (andesites) and JP-1 (peridotite)
were used as test samples. Powder of bulk carbonaceous
chondrites, Orgueil (CI1), Murchison (CM2) and Allende
(CV3) were also employed.
2.4. TEVA Resin Column and Silicate Sample
The TEVA resin column was prepared by packing 0.33
mL of TEVA resin on 0.67 mL of CG-71C in a 1 mL
polypropylene column (5 cm × 5 mm in diameter, Muro-
machi Chemicals Inc., Japan) [4]. The CG-71C resin was
used for absorbing organic materials and controlling the
elution rate.
Silicate powder samples were digested by a usual
sample digestion method in our laboratory [13]. In short,
samples were digested with HF-HClO4, dried to decom-
pose fluorides with HClO4 again [14], evaporated with
HCl, and finally dissolved with 0.5 mol·L1 HNO3. The
final dilution was typically ~250 times (20 mg silicate
samples into 5 mL).
2.5. Iron Separation by the TEVA Resin Column
A Fe separation procedure using the TEVA resin column
is summarized in Table 1. All H2O2 concentration in
Table 1 is 0.05 % (v/v) H2O2. The resin bed was washed
twice with 2 mol·L1 HNO3, subsequently washed once
with 6 mol·L1HCl, and conditioned. The sample solu-
tion containing 1 μg of Fe was added with the solution
containing 0.8 μg Fe double spike and 0.6 mL of 6
mol· L 1 HCl, and dried. Then the sample was dissolved
with 0.1 mL of 6 mol·L1 HCl with H2O2, loaded on the
resin bed and left for 5 min (see Results and Discussion).
The major elements were washed away by addition of
3.2 mL of 6 mol·L1 HCl with H2O2. Then Fe was col-
lected with 6.4 mL of 2 mol·L1 HNO3. The Fe fraction
was dried at 80˚C for 10 hours with one drop of HClO4
to decompose organic materials and small resin particles.
To evaporate HClO4 completely, the sample was finally
heated at 195˚C for 6 hours. Then the purified Fe was
dissolved with 1 mL of 0.5 mol·L1 HNO3, which is
ready for MC-ICP-MS measurement.
Although the flow rate of the TEVA column is 0.3
mL· mi n 1, which is rather high, breakthrough of Fe does
not occur. As the total elution volume including washing
of the column is 32.1 mL, the column chemistry can be
finished within two hours including washing and condi-
tioning the resin bed. This is one of the largest advan-
tages of the TEVA resin column chemistry developed in
this study. In a case of 1 mL of AG 1X8, the flow rate of
a column is ~0.2 mL·min1, and the total elution volume
is ~55 mL [7]. Thus it takes more than 5 hours to collect
Fe. In addition in other studies, one pass of anion ex-
Table 1. Chemical procedure for Fe purification using TE-
VA resin column.
2 mol·L1 HNO3 6.4 mL
water 1.6 mL
2 mol·L1 HNO3 6.4 mL
water 1.6 mL
6 mol·L1 HCl 3.2 mL
Conditioning 6 mol·L1 HCl + H2O23.2 mL
Loading the sample (leave 5 min) 6 mol·L1 HCl + H2O20.1 mL
Removing major elements 6 mol·L1 HCl + H2O23.2 mL
Collecting Fe 2 mol·L1 HNO3 6.4 mL
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change column is not enough, and the column chemistry
is repeated twice or three times to purify Fe in some
cases [7].
The combination with the double spike technique of
this column chemistry gives another advantage that the
Fe isotope determination is more tolerable to loss of iron,
which could occur in the column chemistry.
2.6. Measurement of Fe Isotope Ratios
Isotope ratios of Fe were measured by an MC-ICP-MS,
NEPTUNE housed in PML. Details of the MC-ICP-MS
operating conditions are shown in Table 2 . The spiked 1
μg·mL1 of Fe solution generally gave ~2 × 1010 A sig-
nal for 56Fe+, 57Fe+ and 58Fe+. One run consists of 70
scans, but the first 40 scans were not used and the fol-
lowing 30 scans were used, because the signal increased
slowly and stabilized after around 40 scans. Thirty sets of
isotope ratios of 56Fe/54Fe, 57Fe/54Fe and 58Fe/54Fe
Table 2. MC-ICP-MS operating conditions.
1) Sample introduction and ICP conditions
Nebulizer Micro-flow PFA nebulizer,
flow rate: ~50 μL·min1
Plasma power 1.2 kW (27.12 MHz)
Torch Quartz glass torch
with a sapphire injector
Plasma Ar gas flow rate 15 L·min1
Auxiliary Ar gas flow rate 0.80 L·min1
Nebulizer Ar gas flow rate 0.90 L·min1
2) Desolvator conditions
Desolvator ARIDUS II
Spray chamber temperature 110˚C
Desolvator temperature 160˚C
Sweep gas (Ar) 8 - 9 L·min1
3) Interface
Sampling cone Made of Ni
Skimmer cone Made of Ni (X-skimmer)
4) Data acquisition conditions
Resolution M/ΔM= ~7000
Washingtime 480 sec after measurement
Uptake time 90 sec
Background data integration 4 sec for 1 scan, 20 scans in one run
On-top zeroes
Sample data integration 4 sec for 1 scan, 30 scans in one run
5) Cup configuration
L4 L2 L1 C H1 H2 H4
52Cr* 53Cr* 54Fe 56Fe 57Fe 58Fe 60Ni
*An amplifier with a 1 T resistor.
were obtained for each sample, and the averages of each
ratio were calculated. Then the double spike calculation
(see the next section) was performed. One T ohm resistor
amplifier [15] was used (see Table 2), and 52Cr and 53Cr
were sometimes observed. Isobaric interference of 54Cr
was corrected using 54Cr/52Cr = 0.11339, a power law,
and a normalizing value of 53Cr/52Cr = 0.028226 [16].
Nickel interference was corrected using 58Ni/60Ni = 2.62.
The Fe isotope fractionation is expressed as a per mil
difference from that of the Fe standard, IRMM-014 [17]
by the following equation:
5656 5456 54
sampleIRMM 014
FeFe FeFe Fe1
2.7. Double Spike Calculation
A theory of a double spike is briefly explained in this
section. Each Fe ratio is written using an exponential law
as follows:
norm- 54smp545454
56,57 and 58
mm m
where mi is a mass of iFe; Rnorm-i/54 and Rsmp-i/54 indicate
normalizing and sample isotope ratios of iFe/54Fe. In this
study, Rnorm-i/54 (i = 56, 57 and 58) are 15.698, 0.36233
and 0.048080, respectively, which are those of the stan-
dard IRMM-014 [17]. It should be noted that Rnorm-i/54
and mi are constants.
is a mass fractionation factor,
which is a product of mass fractionation of the sample
and mass discrimination during analysis.
When there is no fractionation in the sample,
equal to 0. Thus the sample isotope ratios become equal
to those of IRMM-014. The purpose is to determine
Rsmp-i/54. For this purpose, a double spike method has
been developed [8-11].
The spike isotope ratios of Rspike-i/54 (i = 56, 57 and 58)
also follow the similar equations:
spike 54pike545454
56,57 and 58
isi i
mm m
When the spike isotope ratios are measured, only
Rspike’-i/54 are obtained, and Rspike-i/54, which are isotope
ratios without mass fractionation (
' = 0), cannot be de-
termined. The method for determination of Rspike-i/54,
which is called as “spike calibration”, is described later.
For the spike-sample mixture, the following equations
mixsmp spik5454 54e
57 and 58
 
mix 54mix545454
56, 57and58
RRmm m
 
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where b is mixing mole ratio of the sample to the spike.
The three isotope ratios of the spike-sample mixtures
(Rmix'-i/54; i = 56, 57 and 58) are measured. As there are
nine variables (Rsmp-i/54, Rmix-i/54, b,
''; i = 56, 57
and 58) and nine equations (Equations (2-4); (8-13)),
there should be solutions for these variables. In this study,
a calculation [9] to solve these equations was followed,
in which exponential approximation is used. Finally, a
fractionation degree of the unknown sample, δ56Fe
(Equation (1)) can be determined.
The spike calibration method is as follows. First, the
pure spike is measured. In this study, the averages of
the pure spike isotope ratios, Rspike'-i/54 (i = 56, 57 and 58)
are obtained to be 25.927, 52.110 and 58.973, respec-
tively. Then, mixtures of the spike and the standard,
IRMM-014 were prepared and measured. Then, the spike
isotope ratio of Rspike-56/54 and
' are determined to mini-
mize the difference between the 56Fe/54Fe ratio of
IRMM-014 and the average of the 56Fe/54Fe ratio ob-
tained from the double spikes calculation using Micro-
soft-Excel “Solver”.
In the actual sample measurement, the spike-sample
mixture is bracketed by the spike-standard mixture. Then
from all the spike-standard isotope ratios, the average of
Rspike-56/54 and the optimum
' in one session are obtained.
Then the 56Fe/54Fe ratios of the sample and the standard
before and after the sample measurement are calculated.
Finally, δ56Fe of each sample is determined. In this cal-
culation, the typical error of 56Fe/54Fe of the standard
solution was 0.06‰ (SD).
3. Results and Discussion
3.1. Kinetic Effects in Adsorption of Fe
For the TEVA resin, kinetic effects in adsorption of Fe
are not negligible [5]. Therefore, the kinetic effects in the
adsorption of Fe were examined. The Fe standard solu-
tions were loaded on the TEVA column with adsorption
time of 5, 10, 25 and 55 min. Then Fe was collected, and
the yields were measured.
Analytical results are shown in Figure 1. The recovery
of Fe was ~100% after 5 min. However, the recovery
yields of >5 min seem a bit lower than 100%. Therefore,
the optimal adsorption reaction time is determined as 5
min. When the adsorption reaction time becomes longer
than 5 min, some Fe ion cannot be desorbed from the
resin by 6.4 mL of 2 mol·L1 HNO3.
3.2. Elution Curves of Fe in the TEVA Column
An elution curve of Fe of the TEVA column is shown in
Figure 2. In the figure, only Mg and Fe are plotted, how-
ever, other major elements in silicate samples such as Na,
Al, P, Ca, Cr, Mn and Ni behave similarly to Mg. As
shown in Figure 2, almost 100 % of major elements in
0 102030405060
Recovery yi eld (%)
Figure 1. The sample adsorption time (min) after sample
loading vs. the recovery yield (%). Error bars are the quan-
titative analytical error of ~7%. The dotted horizontal line
shows 100% yield.
Fraction (%)
LFe fracti on
Figure 2. Elution curves of Fe and Mg for the TEVA col-
umn. Mg represents behaviors of Na, Al, P, K, Ca, Cr, Mn,
Fe, Co and Ni. The horizontal axis shows total eluent vol-
ume (mL). The vertical axis indicates fraction (%) recov-
ered from each eluent fraction (%) compared to the added
amounts on the column. The vertical axis is in the logarith-
mic scale. The horizontal arrows at the top show the eluents
for wash and Fe fraction, respectively. “L” indicates the
sample loading solution.
silicate samples added in the column are washed away in
the first 1.6 mL of 6 mol·L1HCl with H2O2. The total
yield of Fe using actual silicate samples was 93.5 ±
6.5 % (SD). This result means that there could be a small
loss of Fe in this study. Such loss of Fe could cause iso-
topic fractionation [18]. However, such fractionation can
be corrected by the double spike method employed in
this study.
Zinc, Ga, Nb, Mo, Ta, W and U were contained in the
Fe fraction with yields of 60% - 90%. However, in usual
silicate samples, amounts of these elements compared to
1 μg Fe are <ng levels, therefore, effects of these impuri-
ties are inconsequential. Furthermore, total yields of Nb,
Ta and W from the sample solution should be lower than
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those of the starting solution, because co-precipitation
with Ti oxides of Nb, Ta and W should occur during
sample evaporation using HClO4 [19].
The total blanks including sample digestion were 6 ng
(n = 6). As δ56Fe range of all natural samples is <±3‰
[7], δ56Fe of blank can be assumed to be <±3‰. Since Fe
in the sample is 1 μg, the maximum shift of δ56Fe by the
blank should be <±0.02‰. As the repeatability of the
standard solution was found to be 0.06‰, the blank ef-
fects are less than one thirds of the repeatability of the
standard solution. Thus the blank effect can be neglected.
3.3. Evaluation of Accuracy in Fe Isotope Ratio
It is difficult to evaluate the accuracy in stable isotope
mass spectrometry for less popular elements such as Fe,
because the standard materials with accurate isotope ra-
tios are limited. In this study, to examine the accuracy
with variable isotope ratios and matrix elements, the
synthesized samples were made by mixing of two sam-
ples with different isotope ratios and matrix element
compositions. Then the isotope ratios of the mixture were
compared with the calculated isotope ratios. Such mixing
tests were done in studies of Zn and Tl isotopes to evalu-
ate the accuracy of the method [4,20].
For one sample, one of the JB-2 solutions of δ56Fe =
0.27 ± 0.03 (see the next section) was used. For the
other sample, one of ferruginous bodies-digested solu-
tions [21] of δ56Fe = 3.16 ± 0.09 (n = 4) (private com-
munication, Makishima and Nakamura, Okayama Uni-
versity, Dec. 2012) was used. This solution was prepared
by ashing the ferruginous bodies separated from human
lung and dissolving with nitric acid. This solution has a
very low δ56Fe value, and is mostly composed of Fe [21].
The JB-2 and ferruginous bodies-digested solutions were
taken and mixed to contain 1 μg of Fe. Three types of the
mixtures with different matrix compositions were made.
For each type of the mixtures, four or five samples were
made. Each sample was added with 0.4 mL 6 mol·L1
HCl and the Fe double spike, dried and passed through
the TEVA column. Then Fe was collected and its isotope
ratio was determined by MC-ICP-MS.
Analytical results of the δ56Fe value of each mixture
are shown in Table 3. The calculated values are also
shown in Table 3 . The error in calculation for each mix-
ture was based on concentration error of ~5% of two
starting solutions, and no other errors are taken into ac-
count. From Table 3, the observed values are consistent
with the calculated values within 2SD ranges, although
the three samples had different major element composi-
tions. Therefore, it is suggested that the double spike
method for Fe isotope measurements using MC-ICP-MS
in this study gives accurate isotope ratios of Fe.
3.4. Fe Isotope Ratio Measurements in Silicate
Reference Materials
The TEVA column chemistry developed in this study
was applied to analysis of the silicate reference materials,
and analytical results are presented in Table 4, together
with the reported values [11,22-26]. To make the com-
parison between δ56Fe of this study and those of refer-
ences easier, they are plotted in Figure 3. The δ56Fe
value of BHVO-1 in this study of 0.18‰ is a little higher
than those of references [22-24,26]. The δ56Fe values of
AGV-1 and PCC-1 of this study are 0.10 and 0.00‰,
respectively, which are consistent with those of previous
studies [21,25,26] when errors are taken into account.
Repeatability for silicate reference materials (Table 4)
is 0.03‰ - 0.06‰, and the average is 0.05‰. This
0.05‰ should be considered as repeatability of actual
silicate analysis by MC-ICP-MS in this study. As dis-
cussed previously, the blank effects are ±0.02‰, how-
ever, this can be negligible to 0.05‰, which is consid-
ered to be repeatability of this method. This value is
similar to that of the pure standard solution (0.06‰).
The repeatability in the Fe standard solution is com-
pared with those of references here. The SD values of
replicate analyses of the standard solution are 0.013, 0.10,
0.010, 0.050 and 0.041‰ in Chicago [22], Woods Hole
[23], Hannover [24], Madison [25], and Frankfurt [26]
groups, respectively. Therefore the repeatability of the
MC-ICP-MS methods of these leading groups which use
the bracketing method is similar or a bit better than that
of this study. However, all groups use AG 1X8, so they
need repetitive column chemistry in many cases, because
Fe cannot be purified enough by the single column
chemistry to be used in the mass spectrometry. However,
other groups [11] which use AG MP-1 can purify Fe by a
single column chemistry.
Recently, Millet et al. [11] achieved “ultra-precise” Fe
measurements, using the same pair of the double spike,
57Fe-58Fe. They constantly achieved the repeatability of
Table 3. Analytical results of mixing experiments.
Calculated Observed
 δ56Fe SD (‰) δ56Fe SD (‰) n
Mixture#1 1.12 0.08 1.36 0.04 4
Mixture#2 1.90 0.13 2.00 0.19 4
Mixture#3 2.50 0.17 2.64 0.05 5
Table 4. δ56Fe values of USGS and GSJ silicate reference materials and carbonaceous chondrites.
Sample Average SD n References
δ56Fe (‰) (Error is SD)
BHVO-1 0.18 0.03 3 0.105 ± 0.008 [22], 0.110 ± 0.060 [23], 0.109 ± 0.024 [24], 0.117 ± 0.015 [26]
AGV-1 0.10 0.06 3 0.04 ± 0.01 [24]
PCC-1 0.00 0.02 3 0.025 ± 0.012 [22], 0.06 ± 0.06 [25], 0.043 ± 0.013 [26]
JB-1 0.14 0.05 4
JB-2 0.27 0.03 4 0.073 ± 0.014 [11]
JB-3 0.35 0.08 3
JA-1 0.13 0.06 4 0.060 ± 0.010 [11]
JA-2 0.02 0.03 4
JA-3 0.09 0.06 4
JP-1 0.54 0.06 4
Orgueil 0.05 0.06 3 0.015 ± 0.074 [26], 0.38 [27], 0.04 ± 0.06 [28]
Murchison 0.10 0.12 3 0.12 ± 0.06 [28]
Allende 0.03 0.03 3 0.007 ± 0.012 [22], 0.04 [27], 0.06 ± 0.01 [28]
-0.4-0.3-0.2-0.100.1 0.2 0.3 0.4
Orgue il
Al len de
AGV - 1
PCC- 1
56Fe of references
56Fe of this study
Figure 3. Iron isotope ratios (δ56Fe) of this study vs. those of
references. The error bars show one standard deviation of
repeatability (SD, ‰). The vertical and horizontal dotted
lines show δ56Fe = 0 of this study and references, respec-
tively. The dotted slope line indicates slope = 1, which
means that there is no difference in δ56Fe between this study
and references.
0.01‰ using double-spike-MC-ICP-MS. The largest
difference of this study from their study is 1) enrichment
of the double spike and 2) larger usage of the sample.
The 56Fe/54Fe, 57Fe/54Fe and 58Fe/54Fe ratios of the spike
in this study are 24.5521, 53.0182 and 48.0436, while
those of their spike are 2031, 67300 and 6812, respec-
tively. This means that the denominator isotope, 54Fe of
this study is far more abundant than that or Millet et al.
[11], resulting in lower precision. In addition, Millet et al.
[11] used a 100 μL·min1 nebulizer and 2 μg·mL1 solu-
tion, totally 4 times larger amounts of Fe are used than
that in this study.
3.5. Application to Measurements of δ56Fe in
Carbonaceous Chondrites
The δ56Fe values of carbonaceous chondrites, Orgueil,
Murchison and Allende were measured by the method
developed in this study. The δ56Fe value of Orgueil of
this study agrees well with those of Weyer et al. [26] and
Kehm et al. [28], but that of Zhu et al. [27] seems a bit
higher. The δ56Fe values of Allende of this study also
agrees well with those of previous studies [22,27,28].
However, numbers of analyses of carbonaceous chon-
drites in literatures are limited, and carbonaceous chon-
drites could be heterogeneous, thus further studies are
Interference ratios of 54Cr/54Fe and 58Ni/58Fe in these
carbonaceous chondrite analyses after the column chem-
istry were <1.6 × 103 and <1.4 × 104, respectively.
Large Cr and Ni corrections were needed in the TEVA
column chemistry developed in this study, however, the
analytical results suggest that the single-pass TEVA
column is sufficient even in analyses of Cr rich samples
such as peridotites (~3000 μg·g1) or chondrites (~4000
4. Conclusions
Using an extraction resin, TEVA, new column chemistry
for separating Fe has been developed for Fe isotope ratio
determination by MC-ICP-MS. Iron was purified by 6
mol· L 1 HCl + H2O2, and major elements were separated.
Fe was finally recovered with 2 mol·L1 HNO3. The re-
covery yields and total blanks were 93.5% ± 6.5% (SD)
and 6 ng, respectively.
For evaluation of the separation method, Fe isotope ra-
tios were measured by a double spike method using
MC-ICP-MS, respectively. Repeatability obtained from
actual analyses of USGS standard reference materials of
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BHVO-1, AGV-1, PCC-1, and GSJ standard silicate ma-
terials of JB-1, JB-2, JB-3, JA-1, JA-2 and JA-3 were
0.05‰ (SD). Fe isotope ratios of carbonaceous chon-
drites of Orgueil, Murchison and Allende were also de-
termined by the column chemistries developed in this
5. Acknowledgements
The author thanks to E. Nakamura for suggestions and
supports at various aspects of this study. The author is
also grateful to K. Tanaka for doing column chemistry;
and T. Moriguti, C. Sakaguchi and all members of PML
for maintaining the clean laboratory. The author is also
grateful to K. Okabe for donating ferruginous protein
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Open Access IJAMSC
Open Access IJAMSC
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