Accelerator mass spectrometry performance

In order to provide AMS analyses to the broad ocean sciences research community, the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) was established at Woods Hole Oceanographic Institution (Massachusetts) in 1989. Studies performed there include identification of sources of carbon-bearing materials in the water column and sediment, dating of sedimentary samples, investigations of paleocirculation patterns (e.g., from observations of differences in 14C relative abundances in planktonic and benthic foraminifera, and coral cores and cross sections), as well as studies of modern oceanic carbon cycling and circulation. In fact, much that is known about advective and diffusive processes in the ocean comes from measurements of chemical tracers, such as 14C, rather than from direct measurements of water mass flow. 

Vogel, J. S., Southon, J. R.,Nelson, D. E., and Brown,T. A. (1984). Performance of catalytically condensed carbon for use in accelerator mass-spectrometry. Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms 233, 289-293. von Ltitzow, M., Kogel-Knabner, I., Ekschmitt, K., Matzner, E., Guggenberger, G., Marschner,... 

Lappin, G. et al., High-performance liquid chromatography accelerator mass spectrometry Correcting for losses during analysis by internal standardization, Anal. Biochem., 378(1), 93, 2008. 

Gilman, S.D. et al., Analytical performance of accelerator mass spectrometry and liquid scintillation counting for detection of 14C-labeled atrazine metabolites in human urine,... 

Gilman SD, Gee SJ, Hammock BD, Vogel JS, Haack K, Buchholz BA, Freeman SP, Wester RC, Hui X, Maibach HI. Analytical performance of accelerator mass spectrometry metabolites in human urine. Anal Chem 1998 70(16) 3463 3469. 

Vogel JS, Southon JR, Nelaon DE, Brown TA. Performance of catalyticaUy condensed carbon for use in accelerator mass spectrometry. Nucl Instrum Methods 1984 B5 289-293. 

Accelerator mass spectrometry (AMS) is useful to measure extremely low-abundance nuclides (isotope ratio of 10 to 10 relative to its stable isotope), such as Be, C, A1, C1, " Ca, and I, in natural samples. Small amounts of C and T can be measured by AMS on mg size samples of carbon and iodine extracted from 500-ml seawater samples (Povinec et al. 2000). Neutron activation analysis (NAA), radiochemical neutron activation analysis (RNAA), and inductively coupled plasma mass spectrometry (ICP-MS) are useful for the determination of ultra-trace Th and U in geological and cosmochemical samples, and for determination of the concentration of Pu and Pu. Reference marine-biological samples are necessary to test the performance of the analytical methods employed in surveying and monitoring radioactive materials in the sea. An ocean shellfish composite material containing 0.1% w/w Irish Sea mussel, 12% w/w White Sea mussel, and 87.9% w/w Japan Sea oyster has been prepared as the NIST SRM 4358 (The National Institute of Standards and Technology, SRM) in the natural-matrix, environmental-level radioactive SRM series (Altzitzoglou 2000). This NIST SRM 4358 sample will be useful for the determination of the activity of K, Cs, Pb, Ra, Th, and Am. 

Highlights The main interest in studies of uranium content in oceans or seawater is to determine the effect of anthropogenic activities. Therefore, the presence and abundance of the minor isotopes, particularly U, must be accurately determined, and this requires preconcentration and separation of the uranium and the use of accelerator mass spectrometry (AMS) for the analysis. Other mass spectrometric techniques (ICPMS or TIMS) can also be used but with inferior performance. The high salinity of ocean water introduces a matrix effect that could bias ICPMS measurements of the uranium content, so the separation and preconcentration methods described earlier may be needed for precise quantification of uranium (an internal standard can also be used for this purpose). 

In this chapter we will focus on the determination of those nuclides that are widely used as tracers, and where the analysis can be performed without access to highly specialized equipment such as AMS (accelerator mass spectrometry) or TIMS (thermal ionisation mass spectrometry). We describe detailed analytical methods for the nuclides " Th, Th, °Po, °Pb, Be, Ra, Ra, Ra, Ra and Rn. For the determination of other nuclides key references have been listed in Tables 13-1 and 13-2. 

In Laser Ionization Mass Spectrometry (LIMS, also LAMMA, LAMMS, and LIMA), a vacuum-compatible solid sample is irradiated with short pulses ("10 ns) of ultraviolet laser light. The laser pulse vaporizes a microvolume of material, and a fraction of the vaporized species are ionized and accelerated into a time-of-flight mass spectrometer which measures the signal intensity of the mass-separated ions. The instrument acquires a complete mass spectrum, typically covering the range 0— 250 atomic mass units (amu), with each laser pulse. A survey analysis of the material is performed in this way. The relative intensities of the signals can be converted to concentrations with the use of appropriate standards, and quantitative or semi-quantitative analyses are possible with the use of such standards. 

The TOF mass analyzer has a low duty cycle, and the combination with an ion accumulation device such as an ion trap is therefore very advantageous. It offers also MS capabilities with accurate mass measurement. In all acquisition modes, the ions are accelerated into the time of flight for mass analysis. Various other hybrid mass spectrometers with TOF have been described, including quadrupole ion trap [70] and linear ion trap [58]. High energy tandem mass spectrometry can be performed on TOF-TOF mass spectrometers [71, 72]. 

Nicholson, J. K., Lindon, J. C., Scarfe, G. B., Wilson, I. D., Abou-Shakra, F., Sage, A. B., and Castro-Perez, J. (2001). High-performance liquid chromatography linked to inductively coupled plasma mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry for the simultaneous detection and identification of metabolites of 2-bromo-4-trifluoromethyl. Anal. Chem. 73 1491-1494. 

AMS = accelerated mass spectroscopy EDTA = ethylene diamine tetra acetic acid GFAAS = graphite furnace atomic absorption spectrometry ICP-AES = inductively coupled plasma - atomic emission spectroscopy NAA = neutron activation analysis ETAAS = electrothermal atomic absorption spectrometry SEC/ICP-MS = size-exclusion chromatography/ICP-AES/mass spectrometry HLPC/ICP-AES = high-performance liquid chromatography/ICP-AES LAMMA = laser ablation microprobe mass analysis NA = not applicable ppq = parts per quadrillion... 

Popp P, Keil P, Moeder M, et al. 1997. Application of accelerated solvent extraction followed by gas chromatography, high-performance liquid chromatography and gas chromatography-mass spectrometry for the determination of polycyclic aromatic hydrocarbons, chlorinated pesticides and polychlorinated dibenzo-p-dioxins and dibenzofurans in solid wastes. Journal of Chromatography A 774(l-2) 203-211. 

Plumb RS, Johnson KA, Rainville P, Shockcor JP, Williams R, Granger JH, Wilson ID (2006) The detection of phenotypic differences in the metabolic plasma profile of three strains of Zucker rats at 20 weeks of age using ultra-performance liquid chromatog-raphy/orthogonal acceleration time-of-flight mass spectrometry. Rapid Commun. Mass Spectrom. 2006 20 2800-2806. 

Fast atom bombardment mass spectrometry. Fast atom bom-bardment/mass spectrometry (FAB/MS) analyses were performed on a VG ZAB-HF mass spectrometer equipped with an Ion Tech fast atom gun. Xenon gas was activated to 8 kv and 1.5 mA ion current for the fast atom generation. An accelerating voltage of 8 kV was applied to the FAB source. The mass spectrometer was scanned from 800 to 80 amu using an exponential down scan mode at 5 seconds per decade with a 1 second interscan time. The data were recorded with a PDP 11/24 computer and were processed with VG 11/250 software. 

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