PMID- 25707674 OWN - NLM STAT- PubMed-not-MEDLINE DCOM- 20150515 LR - 20150318 IS - 1520-6882 (Electronic) IS - 0003-2700 (Linking) VI - 87 IP - 6 DP - 2015 Mar 17 TI - Ion-pair chromatography coupled to inductively coupled plasma-mass spectrometry (IPC-ICP-MS) as a method for thiomolybdate speciation in natural waters. PG - 3388-95 LID - 10.1021/ac5046406 [doi] AB - Molybdenum precipitates preferentially under reducing conditions; therefore, its occurrence in sediment records is used as an indicator of paleoredox conditions. Although thiomolybdates (MoO4-xSx(2-) with x = 1-4) supposedly are necessary intermediates in the process of molybdenum precipitation under anoxic conditions, there is no information about their abundance in natural environments, because of a lack of element-specific methods with sufficiently low detection limits. Here, we optimized ion-pair chromatographic separation for coupling to an inductively coupled plasma-mass spectrometry detector (IPC-ICP-MS). 2-Propanol (10%-25% gradient) replaced the previously used acetonitrile (25%-75%) as the solvent, to reduce the carbon load into the plasma. In synthetic solutions, formation of thiomolybdates was found to occur spontaneously in the presence of excess sulfide and the degree of thiolation was highest at pH 7. Excess hydroxyl led to a transformation of thiomolybdates to molybdate. Under acidic to neutral conditions, precipitation of molybdenum and hydrolysis of tetrathiomolybdate were observed. Flash-freezing was found to be suitable to stabilize tetrathiomolybdate, with <4% transformation over more than two months. High ionic strengths matrices (>2 mM) negatively affected the detection of molybdate, which eluted mainly in the dead volume, but had no negative effect on higher thiolated molybdates. Detection limits were approximately 10 nM. With the newly developed IPC-ICP-MS method, thiomolybdates were found to form spontaneously in euxinic marine waters after adding a molybdate spike and occur naturally in sulfidic geothermal waters. FAU - Lohmayer, Regina AU - Lohmayer R AD - daggerDepartment of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany. FAU - Reithmaier, Gloria Maria Susanne AU - Reithmaier GM AD - daggerDepartment of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany. FAU - Bura-Nakic, Elvira AU - Bura-Nakic E AD - double daggerCenter for Marine and Environmental Research, Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb, Croatia. FAU - Planer-Friedrich, Britta AU - Planer-Friedrich B AD - daggerDepartment of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany. LA - eng PT - Journal Article DEP - 20150302 PL - United States TA - Anal Chem JT - Analytical chemistry JID - 0370536 EDAT- 2015/02/25 06:00 MHDA- 2015/02/25 06:01 CRDT- 2015/02/25 06:00 PHST- 2015/02/25 06:00 [entrez] PHST- 2015/02/25 06:00 [pubmed] PHST- 2015/02/25 06:01 [medline] AID - 10.1021/ac5046406 [doi] PST - ppublish SO - Anal Chem. 2015 Mar 17;87(6):3388-95. doi: 10.1021/ac5046406. Epub 2015 Mar 2.