Subscriber access provided by MIT Determination of rhenium and platinum in natural waters and sediments, and iridium in sediments by flow injection isotope dilution inductively coupled plasma mass spectrometry Debra C. Colodner, Edward A. Boyle, and John M. Edmond Anal. Chem., 1993, 65 (10), 1419-1425• DOI: 10.1021/ac00058a019 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on April 8, 2009 More About This Article The permalink http://dx.doi.org/10.1021/ac00058a019 provides access to: • Links to articles and content related to this article • Copyright permission to reproduce figures and/or text from this article Analytical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Anal. Chem. 1993, 65, 1419-1425 1419 Determination of Rhenium and Platinum in Natural Waters and Sediments, and Iridium in Sediments by Flow Injection Isotope Dilution Inductively Coupled Plasma Mass Spectrometry Debra C. Colodner,*JEdward A. Boyle, and John M. Edmond Department of Earth, Atmospheric and Planetary Sciences, E34-201, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Methods have been developed to measure Re, Ir, Table I. ComDarison of Instrumental Detection Limits ~ ~~~~~~~~~ and Pt in natural waters and sediments by isotope detection limit, pg dilution inductively coupled plasma mass spec- methode ref Re Ir Pt trometry (ID-ICPMS). The techniques have been GFAAS 75P 300 200 applied to determination of the three elements in SIMS 9 <40b sediments, Pt in seawater, and Re in seawater, RIMS a 200c sediment pore waters, and river waters. In each NTIMS 10 100' <40b case, a stable isotope-enriched spike is added to INAA 11 <O.O2b the sample before processing. Sediments are ACSV 13 O.ld dissolved in all-Teflon digestion vessels using a FI-ID-ICPMS f 5" 6O 14' modified standard kitchen microwave oven. Anion a Three times background. Detection limit not stated; smallest exchange of the chloro complexes of Ir and Pt and samplemeasured. Detection limited by fiientbackground, quoted of the perrhenate ion (Reor-)is used to precon- as 3 times background. 3~~~~~~.e GFAAS, graphite furnace atomic absorption spectrophotometry; SIMS, secondary ion mass spec- centrate the elements and to separate them from trometry; RIMS, resonance ion maw spectrometry; NTIMS, negative concomitants which produce molecular ions in the thermal ionization mass spectrometry; INAA, coincidence/antico- argon plasma resulting in isobaric interferences. incidence instrumental neutron activation analysis; ACSV, adsorptive Samples are then introduced into the ICPMS in a cathodic stripping voltammetry; FI-ID-ICPMS, flow injection isotope small volume (300-600 pL) using flow injection. dilution inductively coupled plasma mass spectrometry. f This work. Overall recoveries were 90 f 10% for all three elements,althoughthe effects of variable recovery and Pt),6,7resonance ion mass spectrometry (RIMS for Re),8 efficiency were minimized by the isotope dilution secondary ion mass spectrometry (SIMS for Re),9 negative technique. The method has detection limits (3 thermal ionization mass spectrometry (NTIMS for Re and times background) of approximately 5 pg of Re, 6 Ir),lO instrumental and radiochemical neutron activation pg of Ir, and 14 pg of Pt. analysis (INAA and RNAA for Re, Ir),l1J2 and adsorptive cathodic stripping voltammetry (ACSV for Pt).13 While the detection limits of these techniques (after preconcentration) are sufficient for analysis of natural samples (Table I), none INTRODUCTION of them allow simultaneous determination of all three Rhenium, iridium, and platinum occur in trace concen- elements. Additionally, GFAAS, RIMS, SIMS, and NTIMS trations in most earth-surface materials. The ability to require extensive purification of the elements in order to determine these elements at natural levels is important for remove interferences and reduce matrix effects. The relative geochemical prospecting,' environmental monitoring,Z and freedom of isotope dilution inductively coupled plasma mass basic geochemical studies.3~~The goals of this work (falling spectrometry (ID-ICPMS) from interferences in variable into the latter category) were to develop methods which would matrices makes it possible to simplify these preconcentration facilitate advances in our understanding of the behavior of procedures signficantly. Re, Ir, and Pt in the marine environment. Interest in the Inductively coupled plasmamass spectrometry has become geochemistry of these elements has arisen from their use as a preferred method of elemental analysis, with detection limits sedimentary indicators of past meteorite impacts (Pt and Ir) for most elements of less than 100 ng/L and rapid sample or of anoxic environments (Re) as well as their economic throughput.14 Previous work demonstrated the utility of importance. The decay of ls7Re (half-life 45 billion years) also offers a new method by which to date ancient sediments.5 (6) Hodge, V. F.; Stallard, M.; Koide, M.; Goldberg, E. Anal. Chem. 1986,58,616-620. Analytical methods for the determination of Re, Ir,and Pt (7)Koide, M.; Hodge, V.; Yang, J. S.; Goldberg, E. D. Anal. Chem. in natural waters, sediments, and rocks include graphite 1987,59, 1802-1805. furnace atomic absorption spectrometry (GFAAS for Re, Ir, (8) Walker, R. J. Anal. Chem. 1988,60,1231-1234. (9)Luck, J. M.Geochimie du rhenium-osmium: Methode et appli- cations. Docteur es-Sciences, Universite de Paris VII, 1982. + Current address: Lamont-Doherty Geological Observatory,Geochem- (10)Creaser, R. A.; Papanastassiou, D. A.; Wasserburg, G. J. Geochim. istry Building, Rt. 9W,Palisades, NY 10964. Cosmochim. Acta 1991, 55, 397-401. (1)Wood, S. A.; Vlasaopoulos, D. Can. Miner. 1990,28,649-663. (11)Murali, A.V.;Parekh,P. P.; Cumming,J. B. Geochim. Cosmochim. (2)Ketterer, M. E. Anal. Chem. 1990,62,2522-2526. Acta 1990,54,889-894. (3)Koide, M.; Hodge, V. F.; Yang, J.; Stallard, M.; Goldberg, E.; (12)Keays, R. R.; Ganapathy, R.; Laul, J. C.; Krahenbuhl, U. R. S.; Calhoun, J.; Bertine, K. Appl. Geochem. 1986, 1, 705-714. Morgan, J. W. Anal. Chim. Acta 1974, 72, 1-29. (4)Goldberg, E. D.; Hodge, V.; Kay, P.; Stallard, M.; Koide, M. Appl. (13)Van Den Berg, C. M. G.; Jacinto, G. S. Anal. Chim. Acta 1988, Geochem. 1986, 1, 227-232. 211, 129-139. (5)Ravizza, G.; Turekian, K. K. Geochim. Cosmochim. Acta 1989,53, (14)Date, A. R.; Gray, A. L. Applications of Inductively Coupled 3257-3263. Plasma Mass Spectrometry; Blackie: London, 1989. 0003-2700/93/0365-1419$04.00/0 0 1993 American Chemical Society 1420 ANALYTICAL CHEMISTRY, VOL. 65, NO. 10, MAY 15, 1993 ICPMS for determination of Re, Ir, and Pt in groundwaters supplied by a Henry rf generator (Model 2000D). The detector and ro~ks;~J~-~~however, reported detection limits were not used was a continuous dynode electron multiplier (GalileoModel sufficient for detailed sediment sampling or surface water 4870) in pulse counting mode, and the signal was processed by studies. Sen Gupta and Gregoirels used acid digestion/sodium a VG MCA and IBM XT-286 computer. peroxide fusion/telluriumcoprecipitation followed by isotope Teflon labware was precleaned and cleaned between samples by soaking in aqua regia (a 3:l mixture of 12 M HCl and 16 M dilution ICPMS to determine iridium (and palladium and "03) for 1 day, followed by 50% HN03 for at least 1 day. ruthenium) in silicate rock samples; however, their method Polypropylene and polyethylene labware was precleaned by calls for 5-g samples and they did not measure concentrations soaking in 10% HC1+ "03. less and 0.1 ppb Ir. Jackson and co-workers'g alsodetermined Reagents and Standards. Reagent-grade "03 (16 M) and Ir and Pt by ICPMS following NiS fire assay/tellurium HCl (6 M) were triply distilled in a Vycor still. Reagent-grade coprecipitation separation (in 15-g samples); however, NiS HF (28.9 M) was singly or doubly distilled in a two-vessel Teflon fire assay collection does not quantitatively separate Re from still (Savillex Corp., MN) at subboiling temperatures and stored sediment fusions.20 The limited sample sizes available from in HF-cleaned Teflon bottles, taking precautions to avoid the sediment cores, and low sedimentary Ir concentrations (<0.1 well-known hazards of HF. Sediment solutions were bubbled ppb), required that we minimize procedural blanks by with Clz (Mattheson, ultrahighpurity) in ordertooxidize Ir before the ion-exchange step. Distilled deionized water (DDW) was simplifying digestion and purification of the samples. This used for all dilutions. was accomplished using a two-stage acid dissolution followed Re standards were prepared from Re metal by dissolution in by a single anion-exchange column. Anion-exchange sepa- concentrated "03. An Ir solution standard was purchased from ration could also be applied with equal success to water SPEX Industries, as well as made by dissolving KZIrCb in 6 M samples. Minimum instrumental detection limits reported HCl; these standards agreed to within 1%. A Pt atomic by Jackson et al. are 600 pg of Ir and 2000 pg of Pt, compared absorption spectrometry standard was purchased from Johnson- to 6 pg of Ir and 14 pg of Pt determined here. Matthey Aesar Corp. Stable isotope-enriched spikes for the McLaren and co-workersZ1discussed the advantages of elements were obtained from Oak Ridge National Laboratory. combining ICPMS with isotope dilution, where elemental The isotope ratios used for isotope dilution calculations were lssRe/lE7Re,1g11r/1g31r, and 19zPt/194Pt,where the spike was concentrations are determined by the measurement of an enriched in the first isotope in each case. The spikes were supplied isotope ratio rather than an absolute ion intensity. Whereas as metals and were dissolved as follows: the Ir spike was fused ion sensitivities may be enhanced or suppressed by nonspec- with NazOzin a zirconium crucible over a Bunsen burner and troscopic interferences from concomitant elements,22isotope dissolved in 3 M HCl;23the Pt spike was dissolved in a 3:l mixture ratio measurements are relatively impervious to these effects.