Open Access

Hafnium isotope analysis of mixed standard solutions by multi-collector inductively coupled plasma mass spectrometry: an evaluation of isobaric interference corrections

  • Min Seok Choi1,
  • Chang-Sik Cheong1Email author,
  • Jeongmin Kim1 and
  • Hyung Seon Shin1
Journal of Analytical Science and Technology20134:1

DOI: 10.1186/2093-3371-4-1

Received: 13 March 2013

Accepted: 13 March 2013

Published: 18 April 2013

Abstract

Background

The Lu-Hf isotope system is widely used to decipher the crustal evolution and mantle differentiation of the Earth. The most critical point in obtaining accurate Hf isotope data is to correct the isobaric interferences of Yb and Lu imposed on the 176Hf peak. In this study, we tested the validity of within-run correction protocol using MC-ICP-MS analysis of Hf standard solutions doped with Yb and Lu.

Findings

We found that the use of carefully selected Yb isotopic composition in the literature resulted in more reliable 176Hf/177Hf ratio. The 176Hf/177Hf ratios analyzed for a series of mixed Hf+Yb+Lu standard solutions could be quite accurately corrected for the mass bias and isobaric interferences. The systematic decreasing trend in the corrected 176Hf/177Hf ratios with increasing Yb/Hf ratios, however, indicates that the mass bias effect cannot be completely removed by the exponential law for samples high in Yb.

Conclusions

A close correlation of the calculated 176Yb/177Hf and 176Lu/177Hf ratios with the gravimetric values sheds light on the direct determination of inter-elemental isotope ratios without chemical purification.

Keywords

Lu-Hf MC-ICP-MS Isobaric interference Mass bias

Introduction

Out of six naturally occurring isotopes of hafnium (174Hf, 176Hf, 177Hf, 178Hf, 179Hf and 180Hf), radiogenic 176Hf is produced by the β- decay of 176Lu with a half-life of 37.2 billion years in terrestrial samples (decay constant λ = 1.865 × 10-11 y-1) (Scherer et al. 2001). Hafnium is more incompatible than lutetium during partial melting of mantle peridotite and thus long-term enrichment of the former relative to the latter in the continental crust has yielded unradiogenic 176Hf/177Hf ratios compared with those in the depleted mantle (Patchett et al. 1981). In this respect, the Lu-Hf system has been effectively used to trace crustal evolution and mantle differentiation of the Earth since the early 1980s (Patchett et al. 1981; Patchett & Tatsumoto 1980; Patchett 1983). Early Lu-Hf works were majorly undertaken by thermal ionization mass spectrometry but recent advances in multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) have revolutionized the analysis of Lu-Hf isotopes, especially when combined with laser-ablation micro-sampling techniques (Thirlwall & Walder 1995; Griffin et al. 2000; Hawkesworth & Kemp 2006).

Accurate 176Hf/177Hf ratio is obtained only after the contribution of isobaric interferences by rare earth elements Yb and Lu on the 176Hf signal is carefully corrected (Woodhead et al. 2004; Iizuka & Hirata 2005). This is particularly important where hafnium purification is unavailable prior to sample introduction to the ion source, as in the case of laser ablation analysis. The present study tests the validity of isobaric interference correction at mass 176 by using MC-ICP-MS analysis of Hf standard solutions doped with Yb and Lu. As the precise values of Yb isotope ratios selected for the correction of mass bias and isobaric contribution critically concern the reliability of corrected 176Hf/177Hf ratio, previous reports on Yb isotopic abundances will also be evaluated.

Instrumentation

In this study, Hf, Yb and Lu isotopic signals were measured by using a Neptune MC-ICP-MS installed at the Korea Basic Science Institute (KBSI) in Ochang. This instrument is a double focusing high-resolution ICP-MS equipped with eight motorized Faraday collectors and one fixed axial channel where ion beam intensities can be measured with either a Faraday collector or an ion counting electron multiplier. The gain calibration biases of the amplifiers are canceled out with the virtual amplifier design in which all Faraday collectors in a certain measurement are sequentially connected to all amplifiers. The Faraday collectors were statically set to simultaneously detect the required isotopes: 172Yb (low 4), 173Yb (low 3), 175Lu (low 2), 176(Yb+Lu+Hf) (low 1), 177Hf (axial), 178Hf (high 1), 179Hf (high 2) and 180Hf (high 3), respectively. The ion beam intensities were optimized by adjusting the torch position, gas flows and ion focus settings. The sensitivity on 180Hf was typically around 25 V/Hf ppm (10+11 Ωresistors) in a low resolution (ca. 400) mode. Details of the other operational parameters are summarized in Table 1.
Table 1

MC-ICP-MS instrumentation and operational parameters

RF forward power

1200 W

RF reflected power

< 2 W

Cooling gas

15 L/min.

Auxiliary gas

0.7 L/min.

Sample gas

1.018 L/min .

Extraction

−2 kV

Focus

−0.621 kV

Acceleration voltage

10 kV

Interface cones

Nickel

Spray chamber

Quartz dual cyclonic

Nebulizer

ESI PFA MicroFlow

Sample uptake rate

100 μL/min.

Instrumental resolution

ca. 400

Mass analyzer pressure

3.2 × 10-9 mbar

Measurement of standard solutions

The basic instrumental capability of the KBSI Neptune MC-ICP-MS was tested by using a JMC 475 Hf standard solution with a concentration of 200 ng ml-1. The exponential law (Russel et al. 1978) was applied for mass bias correction using 179Hf/177Hf = 0.7325 (Patchett et al. 1981). One run consists of 20 cycles, in which one cycle has an integration time of 4.194 s. The average 176Hf/177Hf ratio (0.282167±0.000005, n=5, 2σ S. E.) agrees well with previous recommended values (Blichert-Toft et al. 1997; Nowell et al. 1998; Vervoort & Blichert-Toft 1999) (Table 2). A range of shorter integration times (0.161, 0.262, 0.524 s) were tried with one block of 30 cycles (n=3). All results of 176Hf/177Hf ratio are quite reproducible and accurate (Figure 1) and thus it is concluded that the isotopic composition of a small quantity of hafnium (< 20 ng) could be analyzed with reasonable precision and accuracy in a short (< 1 minute) measurement time.
Table 2

Hf isotope ratios of JMC 475 standard solution

176Hf/ 177Hf

2σ S. E.

178Hf/ 177Hf

2σ S. E.

0.282171

0.000014

1.467249

0.000024

0.282153

0.000020

1.467270

0.000022

0.282167

0.000014

1.467247

0.000018

0.282174

0.000012

1.467248

0.000028

0.282173

0.000019

1.467256

0.000022

Average

   

0.282167

0.000005

1.467254

0.000008

Figure 1

Hafnium isotope measurements of JMC 475 standard solution with integration times of 0.161, 0.262 and 0.524 s.

We also measured Hf isotope ratios of in-house standard solution JMC 14375, delivered from Alfa Aesar of Johnson Matthey Company (stock no. 14375, lot no. 83-084740F, plasma standard solution). The 176Hf/177Hf ratio of this standard solution (300 ng ml-1 Hf), measured with the same analytical design as that for the measurement of JMC 475 standard solution (20 cycles, 4.194 s integration) gave an average of 0.282228±0.000005 (n=10, 2σ S. E.) (Table 3).
Table 3

Hf isotope ratios of JMC 14375 standard solution

176Hf/ 177Hf

2σ S. E.

178Hf/ 177Hf

2σ S. E.

0.282240

0.000014

1.467247

0.000022

0.282231

0.000012

1.467235

0.000030

0.282226

0.000011

1.467231

0.000028

0.282228

0.000011

1.467259

0.000036

0.282233

0.000010

1.467250

0.000038

0.282237

0.000012

1.467252

0.000024

0.282229

0.000015

1.467251

0.000028

0.282215

0.000009

1.467244

0.000028

0.282216

0.000015

1.467230

0.000032

0.282227

0.000010

1.467258

0.000028

Average

   

0.282228

0.000005

1.467246

0.000006

Correction for isobaric interferences

Several analytical strategies were suggested to correct the isobaric interferences by Yb and Lu on 176Hf: (1) Yb is doped with Hf isotope standard solution, and then use revised Yb isotopic compositions that give correct 176Hf/177Hf ratio (Thirlwall & Walder 1995; Griffin et al. 2000), (2) Determine the relationship between the Hf and Yb mass bias factors (Chu et al. 2002), (3) Yb mass bias factor is directly obtained from the Yb isotope ratios simultaneously measured with the Hf analysis (Woodhead et al. 2004; Iizuka & Hirata 2005). The last protocol would be the most effective unless Yb signal intensities are so low that precise isotope ratios are unavailable, considering that the mass bias factor is not a constant value during the MC-ICP-MS measurement (Woodhead et al. 2004; Iizuka & Hirata 2005). In this study, the isobaric interferences of 176Lu and 176Yb on 176Hf were directly estimated by monitoring the intensities of interference-free Lu and Yb signals as the following:
176 Hf measured = 176 Hf + Lu + Yb measured 175 Lu measured × 176 Lu / 175 Lu true × M 175 / M 176 Lu β Lu [ 173 Yb measured × 176 Yb / 173 Yb true × M 173 / M 176 Yb β Yb ]
where β(Lu) and β(Yb) are respective exponential mass bias factors for Lu and Yb, and “M” denotes the mass of the isotope. The β(Hf) and β(Yb) values were measured by monitoring 179Hf/177Hf and 172Yb/173Yb ratios for a mixed standard solution of which concentrations were 298.7 ng ml-1 for JMC 14375 Hf, 30.4 ng ml-1 for Accu-Trace Yb (lot no. B4035064-2B, reference standard) and 3.0 ng ml-1 for Accu-Trace Lu (lot no. B8045141, reference standard). For the calculation of β(Yb) and isobaric interference correction, an accurate Yb isotopic composition is needed but previous reports are not uniform (Chu et al. 2002; McCulloch et al. 1977; Segal et al. 2003; Thirlwall & Anczkiewicz 2004; Vervoort et al. 2004). The 176Hf/177Hf ratio of the mixed standard solution was calculated using different sets of Yb isotope ratios as the followings.
172 Yb / 173 Yb = 1.35260 Chu et al. 2002 , 1.35704 McCulloch et al. 1977 , 1.35428 Segal et al. 2003 , 1.35823 Thirlwall & Anczkiewicz 2004 , 1.35272 Vervoort et al. 2004 176 Yb / 173 Yb = 0.79618 Chu et al. 2002 , 0.78759 McCulloch et al. 1977 , 0.79381 Segal et al. 2003 , 0.78696 Thirlwall & Anczkiewicz 2004 , 0.79631 Vervoort et al. 2004
(2)
As depicted in Figure 2, the results of 11 measurements (20 cycles, integration time=4.194 s) indicate that reports of Yb isotope ratios in (Chu et al. 2002; McCulloch et al. 1977) yielded incorrectly high 176Hf/177Hf ratios. Comparable 176Hf/177Hf ratios with that of unspiked JMC 14375 Hf (0.282228±0.000005) could be obtained by using Yb isotope ratios in (Segal et al. 2003; Thirlwall & Anczkiewicz 2004; Vervoort et al. 2004), and thus we hereafter give 1.35823 and 0.78696 as the (172Yb/173Yb)true and (176Yb/173Yb)true values, respectively (Thirlwall & Anczkiewicz 2004) for correcting mass fractionation of Yb and calculating its isobaric contribution to 176Hf. Internal normalization of mass fractionation is not available for Lu, because it has only two natural isotopes (175Lu and 176Lu). In this study, the β(Lu) is assumed to be identical to the β(Hf), and (176Lu/175Lu)true of 0.026549 (Chu et al. 2002) is employed to calculate the signal intensities of 176Lu. Possible difference between the β(Lu) and β(Hf) values does not affect the corrected Hf isotope ratio significantly because the contribution of 176Lu to 176Hf is typically very small in the crustal materials (ca. 1%, (Rudnick & Fountain 1995)). The β(Yb) value of each cycle is plotted against the β(Hf) value in Figure 3. This diagram confirms that the two values are not identical, and should be measured independently during the run. They are positively correlated with each other but a distinct regression line is not identified.
Figure 2

The 176 Hf/ 177 Hf isotopic measurements for a mixed standard solution of which concentrations were 298.7 ng ml -1 for JMC 14375 Hf, 30.4 ng ml -1 for Accu-Trace Yb and 3.0 ng ml -1 for Accu-Trace Lu. The isobaric interference corrections were made after previous reports on Yb isotopic composition (Chu et al. 2002; McCulloch et al. 1977; Segal et al. 2003; Thirlwall & Anczkiewicz 2004; Vervoort et al. 2004). Solid and dashed lines respectively represent the average 176Hf/177Hf of JMC 14375 and 2σ S. D. on the mean for the unspiked solution.

Figure 3

Relation between the Hf and Yb mass bias factors ( β (Hf) and β (Yb)) for the same mixed standard solution as that described in Figure 2 .

We further tested the validity of isobaric interference correction described above by using Hf+Yb+Lu solutions mixed with different elemental proportions (Hf = 300 ng ml-1 JMC 14375, Hf:Yb:Lu ≈ 200:10:1, 100:10:1, 50:10:1, 30:9:1). The results with 10 blocks of 20 cycles (integration time = 4.194 s) (Table 4) show that the correction protocol works pretty well. There is, however, a systematic decreasing trend in the corrected 176Hf/177Hf ratio with increasing Yb/Hf ratios, indicating that mass bias is not perfectly corrected by the exponential law for samples high in Yb. The 176Yb/177Hf and 176Lu/177Hf ratios are calculated as the followings (Iizuka & Hirata 2005):
176 Lu / 177 Hf corrected = 176 Lu / 175 Lu true × 175 Lu / 177 Hf measured × M 177 / M 175 β Hf 176 Yb / 177 Hf corrected = 176 Yb / 173 Yb true × 173 Yb / 177 Hf measured × M 176 Yb / M 173 β Yb / M 176 Yb / M 177 β Hf
Table 4

Hf-Lu-Yb isotopic data for the mixed standard solutions

 

176Hf/ 177Hf

2σ S. E.

176Lu/ 177Hf

2σ S. E.

176Yb/ 177Hf

2σ S. E.

Hf = 286.2 ng/ml, gravimetric 176Lu/177Hf =0.00072, 176Yb/177Hf = 0.03680

 

0.282214

0.000023

0.0009273

0.0000009

0.04969

0.00007

 

0.282224

0.000024

0.0009419

0.0000004

0.05074

0.00003

 

0.282228

0.000016

0.0009406

0.0000005

0.05068

0.00004

 

0.282246

0.000025

0.0009408

0.0000014

0.05071

0.00011

 

0.282218

0.000022

0.0009431

0.0000009

0.05087

0.00007

 

0.282227

0.000020

0.0009428

0.0000005

0.05084

0.00004

 

0.282237

0.000025

0.0009438

0.0000004

0.05093

0.00004

 

0.282218

0.000024

0.0009348

0.0000003

0.05021

0.00002

 

0.282217

0.000017

0.0009365

0.0000006

0.05037

0.00005

 

0.282228

0.000014

0.0009397

0.0000004

0.05055

0.00004

Average

0.282226

 

0.0009391

 

0.05056

 

2σ S. E.

0.000006

 

0.0000031

 

0.00024

 

Hf = 298.7 ng/ml, gravimetric 176Lu/177Hf = 0.00142, 176Yb/177Hf = 0.07170

 

0.282201

0.000036

0.001851

0.000001

0.09813

0.00011

 

0.282221

0.000023

0.001856

0.000001

0.09855

0.00012

 

0.282229

0.000030

0.001866

0.000001

0.09932

0.00012

 

0.282195

0.000029

0.001869

0.000002

0.09954

0.00011

 

0.282218

0.000024

0.001867

0.000003

0.09942

0.00020

 

0.282197

0.000026

0.001872

0.000002

0.09975

0.00016

 

0.282210

0.000036

0.001874

0.000002

0.09992

0.00012

 

0.282210

0.000029

0.001868

0.000001

0.09944

0.00009

 

0.282208

0.000022

0.001873

0.000001

0.09983

0.00012

 

0.282245

0.000029

0.001874

0.000002

0.09994

0.00012

 

0.282217

0.000033

0.001874

0.000001

0.09995

0.00010

Average

0.282214

 

0.001868

 

0.09943

 

2σ S. E.

0.000009

 

0.000004

 

0.00035

 

Hf = 302.8 ng/ml, gravimetric 176Lu/177Hf = 0.00280, 176Yb/177Hf = 0.14151

 

0.282207

0.000033

0.003641

0.000003

0.19491

0.00025

 

0.282216

0.000040

0.003662

0.000004

0.19654

0.00031

 

0.282215

0.000045

0.003674

0.000004

0.19747

0.00029

 

0.282185

0.000049

0.003674

0.000004

0.19748

0.00030

 

0.282195

0.000030

0.003682

0.000002

0.19807

0.00013

 

0.282206

0.000042

0.003681

0.000002

0.19788

0.00014

 

0.282222

0.000033

0.003676

0.000003

0.19749

0.00021

 

0.282196

0.000039

0.003675

0.000004

0.19732

0.00029

 

0.282233

0.000031

0.003681

0.000003

0.19773

0.00025

 

0.282184

0.000033

0.003671

0.000004

0.19685

0.00033

Average

0.282206

 

0.003672

 

0.19717

 

2σ S. E.

0.000010

 

0.000008

 

0.00057

 

Hf = 307.1 ng/ml, gravimetric 176Lu/177Hf = 0.00413, 176Yb/177Hf = 0.21282

 

0.282205

0.000030

0.005275

0.000003

0.28226

0.00022

 

0.282176

0.000037

0.005289

0.000005

0.28333

0.00036

 

0.282198

0.000028

0.005289

0.000003

0.28343

0.00026

 

0.282200

0.000045

0.005298

0.000004

0.28407

0.00029

 

0.282200

0.000036

0.005300

0.000003

0.28426

0.00021

 

0.282151

0.000035

0.005308

0.000007

0.28487

0.00051

 

0.282171

0.000047

0.005296

0.000007

0.28401

0.00051

 

0.282172

0.000041

0.005315

0.000004

0.28550

0.00030

 

0.282203

0.000038

0.005233

0.000007

0.27905

0.00052

 

0.282164

0.000037

0.005281

0.000004

0.28276

0.00026

Average

0.282184

 

0.005288

 

0.28335

 

2σ S. E.

0.000012

 

0.000014

 

0.00111

 

The calculated ratios are not identical to the gravimetric values (Table 4) due to differences in elemental sensitivity but the two values are quite perfectly correlated with each other ((176Lu/177Hf)calculated = 1.277 × (176Lu/177Hf)gravimetric; (176Yb/177Hf)calculated = 1.327 × (176Yb/177Hf)gravimetric, R2 > 0.98), leaving a possibility that these inter-elemental isotope ratios can be accurately measured directly from the sample solution without chemical purification.

Conclusions

We tested the capability of a Neptune MC-ICP-MS in obtaining accurate Hf isotope ratios of the mixed Hf+Yb+Lu standard solution. Careful selection of Yb isotope compositions was essential for the correction of mass bias and isobaric interferences from Yb and Lu on the 176Hf peak. The validity of within-run correction protocol described here was confirmed by analyzing a series of mixed standard solutions, although the systematic decreasing trend in the corrected 176Hf/177Hf ratio with increasing Yb/Hf ratios indicated that mass bias was not completely corrected by the exponential law for samples high in Yb. A quite perfect correlation of the calculated 176Yb/177Hf and 176Lu/177Hf ratios with the gravimetric values leaves a probability to determine the inter-elemental isotope ratios directly from the sample solution without chemical separation.

Declarations

Acknowledgements

This study was supported by Korea Basic Science Institute grants (G32221, G32210 and C32710). Valuable comments of two anonymous reviewers are acknowledged.

Authors’ Affiliations

(1)
Division of Earth and Environmental Sciences, Korea Basic Science Institute

References

  1. Blichert-Toft J, Chauvel C, Albarede F: Separation of Hf and Lu for high-precision isotope analysis of rock samples by magnetic sector-multiple collector ICP-MS. Contrib. Mineral. Petrol 1997, 127: 248–260. 10.1007/s004100050278View ArticleGoogle Scholar
  2. Chu NC, Taylor RN, Chavagnac V, Nesbitt RW, Boella M, Milton JA: Hf isotope ratio analysis using multi-collector inductively coupled plasma mass spectrometry: an evaluation of isobaric interference corrections. J. Anal. At. Spectrom 2002, 17: 1567–1574. 10.1039/b206707bView ArticleGoogle Scholar
  3. Griffin WL, Pearson NJ, Belousova EA, Jackson SE, O'Reily SY, van Achterberg E, Shee SR: The Hf-isotopie composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites. Geochim. Cosmochim. Acta 2000, 64: 133–147. 10.1016/S0016-7037(99)00343-9View ArticleGoogle Scholar
  4. Hawkesworth CJ, Kemp AIS: Using hafnium and oxygen isotopes in zircons to unravel the record of crustal evolution. Chem. Geol 2006, 226: 144–162. 10.1016/j.chemgeo.2005.09.018View ArticleGoogle Scholar
  5. Iizuka T, Hirata T: Improvements of precision and accuracy in in situ Hf isotope microanalysis of zircon using the laser ablation-MC-ICPMS technique. Chem. Geol 2005, 220: 121–137. 10.1016/j.chemgeo.2005.03.010View ArticleGoogle Scholar
  6. McCulloch MT, Rosman KJR, De Laeter JR: The isotopic and elemental abundance of ytterbium in meteorites and terrestrial samples. Geochim. Cosmochim. Acta 1977, 41: 1703–1707. 10.1016/0016-7037(77)90202-2View ArticleGoogle Scholar
  7. Nowell GM, Kempton PD, Noble SR, Fitton JG, Saunders AD, Mahoney JJ, Taylor RN: High precision Hf isotope measurements of MORB and OIB by thermal ionization mass spectrometry: insights into the depleted mantle. Chem. Geol 1998, 149: 211–233. 10.1016/S0009-2541(98)00036-9View ArticleGoogle Scholar
  8. Patchett PJ: Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution. Geochim. Cosmochim. Acta 1983, 47: 81–91. 10.1016/0016-7037(83)90092-3View ArticleGoogle Scholar
  9. Patchett PJ, Tatsumoto M: Hafnium isotope variations in oceanic basalts. Geophy. Res. Lett 1980, 7: 1077–1080. 10.1029/GL007i012p01077View ArticleGoogle Scholar
  10. Patchett PJ, Kouvo O, Hedge CE, Tatsumoto M: Evolution of continental crust and mantle heterogeneity: evidence from Hf isotopes. Contrib. Mineral. Petrol 1981, 78: 279–297.View ArticleGoogle Scholar
  11. Rudnick RL, Fountain DM: Nature and composition of the continental crust: A lower crustal perspective. Rev. Geophys 1995, 33: 267–309. 10.1029/95RG01302View ArticleGoogle Scholar
  12. Russel WA, Papanastassiou DA, Tombrello TA: Ca isotope fractionation on the earth and other solar system materials. Geochim. Cosmochim. Acta 1978, 42: 1075–1090. 10.1016/0016-7037(78)90105-9View ArticleGoogle Scholar
  13. Scherer E, Münker C, Mezger K: Calibration of the lutetium-hafnium clock. Science 2001, 293: 683–687. 10.1126/science.1061372View ArticleGoogle Scholar
  14. Segal I, Halicz L, Platzner IT: Accurate isotope ratio measurements of ytterbium by multi-collector inductively coupled plasma mass spectrometry applying erbium and hafnium in an improved double external normalization procedure. J. Anal. At. Spectrom 2003, 18: 1217–1223. 10.1039/b307016fView ArticleGoogle Scholar
  15. Thirlwall MF, Anczkiewicz R: Multidynamic isotope ratio analysis using MC-ICP-MS and the causes of secular drift in Hf, Nd and Pb isotope ratios. Int. J. Mass Spectrom 2004, 235: 59–81. 10.1016/j.ijms.2004.04.002View ArticleGoogle Scholar
  16. Thirlwall MF, Walder AJ: In-situ hafnium isotope ratio analysis of zircon by inductively coupled plasma multiple collector mass spectrometry. Chem. Geol 1995, 122: 241–247. 10.1016/0009-2541(95)00003-5View ArticleGoogle Scholar
  17. Vervoort JD, Blichert-Toft J: Evolution of the depleted mantle: Hf isotope evidence from juvenile rocks through time. Geochim. Cosmochim. Acta 1999, 63: 533–556. 10.1016/S0016-7037(98)00274-9View ArticleGoogle Scholar
  18. Vervoort JD, Patchett PJ, Söderlund U, Baker M: Isotopic composition of Yb and the determination of Lu concentrations and Lu/Hf ratios by isotope dilution using MC-ICPMS. Geochem. Geophys. Geosystem 2004., 5: Q11002 10.1029/2004GC000721Google Scholar
  19. Woodhead J, Hergt J, Shelley M, Eggins S, Kemp R: Zircon Hf-isotope analysis with an excimer laser, depth profiling, ablation of complex geometries, and concomitant age estimation. Chem. Geol 2004, 209: 121–135. 10.1016/j.chemgeo.2004.04.026View ArticleGoogle Scholar

Copyright

© Choi et al.; licensee Springer. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Advertisement