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Towards Quantifying the Composition of Expanded Austenite
Published in Tom Bell, Katsuya Akamatsu, Stainless Steel 2000, 2020
M.P. Fewell, P. Garlick, J.M. Priest, P.T. Burke, N. Dytlewski, K.E. Prince, K.T. Short, R.G. Elliman, H. Timmers, T.D.M. Weijers, B. Gong
The present work extends a previous study of nitrided stainless steel by secondary-ion mass spectrometry (SIMS),11 the principal finding of which is that the sputter rate (crater depth vs sputter time) is constant in nitrided AISI 316 stainless steel. As in the earlier work, we used the Cameca IMS 5F magnetic-sector mass spectrometer located at ANSTO, employing a 10 keV Cs+ beam with the sample biased at +4.5 kV and counting caesium binary ions MCs+, where M is the species being monitored. Matrix effects in the yields of MCs+ ions are much less pronounced than those in the atomic ions M+,12 but are not necessarily absent.13 The caesium beam was rastered over a square 250 μm on a side and sputtered ions were collected from circular area 60 μm in diameter centred on the raster pattern. During the determination of a depth profile, several elements were monitored by counting for 1.0 s at each chosen value of mass, in repetitive sequence from the lowest mass to the highest.
The Monitoring of Exposure to Carcinogens by the GC-MS Determination of Alkylated Amino Acids in Hemoglobin and of Alkylated Nucleic Acid Bases in Urine
Published in Frederick C. Kopfler, Gunther F. Craun, Environmental Epidemiology, 2019
Peter B. Farmer, David E. G. Shuker, Eric Bailey
At present all alkylated bases that we have studied are analyzed as derivatives by capillary GC-MS, following their partial purification from the urine. An alternative approach that we are now considering is the use of a triple sector mass spectrometer with analysis of collision spectra ions. As an example of this technique, Figure 5(b) shows a daughter ion spectrum (collision gas air, collision energy 13eV), (obtained with kind permission of VG Analytical Ltd. on a 7070 EQ mass spectrometer), of 7-methylguanine. Ions of mass 165 (M+ for 7-methylguanine) were collected by the electric and magnetic sectors, fragmented in a collision cell, and the resulting ions focused in the final quadrupole sector. Figure 5(a) illustrates the spectrum obtained in a similar fashion when rat urine (3 1) was placed on the MS probe, and clearly shows the potential of the method for detecting alkylated products in urine. The background level of 7-methylguanine that is being seen in Figure 5(a) is ca. 10 μg/ml.
Probing the nature of soil organic matter
Published in Critical Reviews in Environmental Science and Technology, 2022
Zhe (Han) Weng, Johannes Lehmann, Lukas Van Zwieten, Stephen Joseph, Braulio S. Archanjo, Bruce Cowie, Lars Thomsen, Mark J. Tobin, Jitraporn Vongsvivut, Annaleise Klein, Casey L. Doolette, Helen Hou, Carsten W. Mueller, Enzo Lombi, Peter M. Kopittke
Technical background: Nanoscale secondary ion mass spectrometry (NanoSIMS) is an analytical technique that provides information of the microscale (∼50–100 nm spatial resolution) elemental and isotopic composition of a material (Herrmann et al., 2007; Hoppe et al., 2013; Mueller et al., 2013). A primary ion beam (either Cs+ or O−) is accelerated onto the sample surface which releases secondary ion particles. These ions are separated according to their mass to charge ratio in a sector mass spectrometer. The primary ion beam can be focused to a spot of sample to achieve a lateral resolution of up to 50 nm, with scanned area typically between 5 × 5 μm up to 30 × 30 μm (Mueller et al., 2012; Steffens et al., 2017).