HR: 0800h
AN: PP31B-1540    [Abstracts]
TI: How accurate and precise is multiple-collector inductively coupled plasma mass spectrometery for measurement of δ³⁴S_V-CDT and δ³³S_V-CDT?
AU: * Mason, P R
EM: mason@geo.uu.nl
AF: Department of Earth Sciences, Utrecht University, Budapestlaan 4, Utrecht, 3584CD Netherlands
AU: Kosler, J
EM: jan.kosler@geo.uib.no
AF: Department of Earth Science, University of Bergen, Allegaten 41, Bergen, N5007 Norway
AU: Vroon, P
EM: pieter.vroon@falw.vu.nl
AF: Faculty of Earth and Life Sciences, Free University Amsterdam, De Boelelaan 1085 , Amsterdam, 1081 HV Netherlands
AB: Stable isotopes of sulfur(³²S, ³³S, ³⁴S) were measured directly in solutions of diverse composition or in solids by laser ablation using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Simplified sample preparation, made possible by this new technique, avoids the risk of fractionation induced by inefficient conversion during chemical pretreatment. In addition, analysis by laser ablation provides key spatial information in minerals and sediments on a scale of ca. 100 microns. Unfortunately this technique is particularly challenging for sulfur due to interference from O- and N-based polyatomic ions as well as relatively large instrumental mass bias. In this study we compare two independent new methods, one which uses a hexapole collision and reaction cell for interference attenuation whilst the other employs high mass resolution by sector field mass spectrometry for interference avoidance. Mass discrimination was corrected using either a ³⁷Cl/³⁵Cl or a ³⁰Si/²⁹Si standard solution for external normalization with standard exponential law correction routines. Equivalent highly accurate data were obtained by both methods but only when combining the external isotope normalization with secondary calibration against matrix-matched standards. This approach resulted in data for δ³⁴S to within 0.5 per mil of reference values with typical external precision of 0.2 (solution nebulization) to 0.6 per mil (laser ablation). Additional matrix effects were apparent in laser ablation experiments when standardizing sulfur and sulfate rich samples against IAEA-S series AgS sulfide standard reference materials.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1094 Instruments and techniques
DE: 4870 Stable isotopes (0454, 1041)
DE: 4894 Instruments, sensors, and techniques
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005