LA - ICP - QQQ - MS
The inductively coupled plasma-triple-quadrupole-mass spectrometer coupled to a laser ablation system (LA-ICP-QQQ-MS) is being developed to measure multiple sulfur isotopes. This system has the ability to reduce polyatomic interferences, which enables increased sensitivity of light elemental masses. The most remarkable characteristics are the low detection limits achievable for sulfur and the large mass resolution required to remove polyatomic interferences. The research instrument comprises: 1) Resolution (Applied Spectra) S-155 Excimer laser with 193 nm wavelength and a large cell 2) Agilent 8900 Inductively coupled plasma triple quadruple mass spectrometer.
The AxioImager M2 is a high-performance microscope equipped with a motorized X-Y-Z stage to create seamless transmitted and reflected-light mosaics of polished thin sections. These mosaics are used as a basemap to identify mineral targets for analysis and define offline ion probe/ablation sequences for isotopic analysis.
Sulfur Extraction Line
Four sulfur extraction lines are installed and can be used simultaneously or independently. The sulfur extraction line is the first step to performing multiple sulfur isotopes analysis in bulk. The second step corresponds to the fluorination of the extracted sample. The extraction consists of an acid attack on a sulfur-rich material to release H2S which is then conveyed in a solution of silver nitrate (AgNO3) to precipitate as silver sulfide (Ag2S). The latter is then used in the fluorination step. All sulfur-rich minerals can be extracted (except sulfosalts) even if they are disseminated throughout an entire rock, only the sulfur-rich phases will be extracted. Here we use a Chromium Reduced Sulfides (CRS) acid solution based on the study of Canfield et al. (1986) to extract sulfides. It can also be possible to extract sulfates by using a Strongly Reducing Hydriodic Hypophosphorous acid solution (STRIP) as described in Kitayama et al. (2017). Both sulfides and sulfates can be extracted sequentially on the same sample containing minerals of both sulfur valences.
Canfield, D.E., Raiswell, R., Westrich, J.T., Reaves, C.M., Berner, R.A., 1986. The use of chromium reduction in the analysis of reduced inorganic sulfur in sediments and shales. Chem. Geol. 54(1-2), 149-155.
Kitayama, Y., Thomassot, E., Galy, Α., Golovin, A., Korsakov, A., d'Eyrames, E., Assayag, N., Bouden, N. Ionov, D., 2017. Co-magmatic sulfides and sulfates in the Udachnaya-East pipe (Siberia): A record of the redox state and isotopic composition of sulfur in kimberlites and their mantle sources. Chem. Geol. 455, 315-330.