Simultaneous measurement of sulfur and lead isotopes in sulfides using nanosecond laser ablation coupled with two multi-collector inductively coupled plasma mass spectrometers
Abstract
We herein report the coupling of a nanosecond laser ablation system with a large-scale multi-collector inductively coupled plasma mass spectrometer (Nu1700 MC-ICPMS, NP-1700) and a conventional Nu Plasma II MC-ICPMS (NP-II) for the simultaneous laser ablation and determination of in situ S and Pb isotopic compositions of sulfide minerals. We found that the required aerosol distribution between the two spectrometers depended on the Pb content of the sample. For example, for a sulfide containing 100-3000 ppm Pb, the aerosol was distributed between the NP-1700 and the NP-II spectrometers in a 1:1 ratio, while for lead contents >3000 and <100 ppm, these ratios were 5:1 and 1:3, respectively. In addition, S isotopic analysis showed a pronounced matrix effect, so a matrix-matched external standard was used for standard-sample bracketing correction. The NIST NBS 977 (NBS, National Bureau of Standards; NIST, National Institute of Standards & Technology) Tl (thallium) dry aerosol internal standard and the NIST SRM 610 (SRM, standard reference material) external standard were employed to obtain accurate results for the analysis of Pb isotopes. In tandem experiments where airflow conditions were similar to those employed during stand-alone analyses, small changes in the aerosol carrier gas flow did not significantly influence the accurate determination of S and Pb isotope ratios. In addition, careful optimization of the flow ratio of the aerosol carrier (He) and makeup (Ar) gases to match stand-alone analytical conditions allowed comparable S and Pb isotope ratios to be obtained within an error of 2 s analytical uncertainties. Furthermore, the results of tandem analyses obtained using our method were consistent with those of previously reported stand-alone techniques for the S and Pb isotopes of chalcopyrite, pyrite, galena, and sphalerite, thus indicating that this method is suitable for the simultaneous analysis of S and Pb isotopes of natural sulfide minerals, and provides an effective tool to determine S and Pb isotope compositions of sulfides formed through multi-stage deposition routes.
- Publication:
-
Journal of Asian Earth Sciences
- Pub Date:
- April 2018
- DOI:
- 10.1016/j.jseaes.2017.12.040
- Bibcode:
- 2018JAESc.154..386Y
- Keywords:
-
- 2s;
- ±2 standard errors (SE) or ±2 standard deviations (SD);
- CBI-3;
- natural galena;
- Cpy-1;
- natural chalcopyrite;
- GC;
- Gn;
- galena;
- IAEA-S-1;
- pressed pellets of Ag<SUB>2</SUB>S power;
- LA-ICP-MS;
- laser ablation inductively coupled plasma mass spectrometry;
- MC-ICP-MS;
- multi-collector inductively coupled plasma mass spectrometer;
- NBS;
- National Bureau of Standards;
- NBS123;
- natural sphalerite;
- NIST;
- National Institute of Standards & Technology;
- NP-II;
- Nu Plasma II MC-ICP-MS;
- NP-1700;
- Nu1700 MC-ICP-MS;
- Py-4;
- natural pyrite;
- Q-ICP-MS;
- quadrupole ICP-MS;
- RP;
- resolving power;
- RSD;
- relative standard deviation;
- SRM;
- standard reference material;
- SSB;
- standard-sample bracketing;
- TMR;
- true mass resolution;
- YN411m;
- molten chalcopyrite