Accelerator Mass Spectrometry AMS

Accelerator Mass Spectrometry (AMS) was developed to overcome the fundamental limitations of both the decay-counting as well as conventional mass spectrometry. AMS method takes much less time, e.g., 10,000 atoms of 14c 

Through the AMS analysis technique, the isotopes typically measured include a handful of long-lived radioisotopes that are rare / scarce due to their instability, yet difficult to measure by their infrequent decay. The negative ion source eliminates the interference of with C. AMS has been successfully applied in the fields of archeology (Wendorf 1987, Zhou et al. 2000) and anthropology (Taylor 1987, Hofmeijer et al. 1987). The nondating 

The applications of AMS in the major research areas are being undertaken in more than 50 research laboratories of the world. These works are published in all major international journals as well as presented in international conferences. The proceedings of the Ninth International Conference on AMS have been edited by Nakamura et al. (2004). The major areas of research, in which AMS has made significant impact, are described in Sect. 8.8. 

AMS isotope may also reach the detector. The stable isotope is collected in a Faraday cup and its yield is determined from the accumulated charge. 

Since the AMS generally determines the ratio of the rare isotope to the most abundant isotope of the same element (say C/ C), this is accomplished by accelerating ions of the abundant isotope as well as the rare isotope. The rare isotope being examined is always measured as a ratio of a stable, more abundant (but not too abundant) isotope, e.g., as a ratio of which acts as an internal standard and provides a clear signature to differentiate the rare isotope from the background. The ratio can be determined from 

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A more recently developed technique, known as the accelerator mass spectrometry (AMS) radiocarbon dating technique, based on counting, in a mass spectrometer, the relative amount of radiocarbon to stable carbon isotopes in a sample (see Textbox 10). 

The impact of this new technique, which was called Accelerator Mass Spectrometry (AMS), on the radiocarbon and archaeologist communities, was immediate and revolutionary. The introduction of AMS is indeed recognized by some as the third revolution in radiocarbon dating[22,23] and it has provided the opportunity to date very precious finds by collecting very small samples. The interest in developing the technique of AMS was so evident that, just few years after the measurements cited above, a first dedicated AMS system (based on a tandem accelerator) was designed and built [24] then, the first dedicated... 

SIMS) to map specific compounds in cross-sections, and atomic isotopic analysis for dating using accelerator mass spectrometry (AMS). 

Principal characteristics of small sample liquid scintillation counting (lsc), gas proportional low-level counting (11c) and atom counting by accelerator mass spectrometry (AMS) are summarized in Table 1, and systems we have used are shown in figure 1. The most important differences (apart from cost and availability)... 

In addition to Chapters 3-5 in this book, two other symposium papers were presented on the characteristics and applications of Accelerator Mass Spectrometry (AMS) ... 

Newer instrumental methods of potential utility in organic analysis of environmental and geological biomarkers are compound specific isotope analysis (CSIA) and carbon-14 dating with accelerator mass spectrometry (AMS). CSIA provides the carbon isotope composition of individual... 

For a better idea of the toxicity of VOCs, we can look more closely at some studies of TCE (Bogen et al., 1998). In vitro uptake of C-14-labeled trichloroethylene (TCE) from dilute (similar to 5-ppb) aqueous solutions into human surgical skirt was measured using accelerator mass spectrometry (AMS). The AMS data obtained positively correlate with (p approximate to 0) and vary significantly nonlinearly with (p = 0.0094) exposure duration. These data are inconsistent (p approximate to 0) with predictions made for TCE by a proposed EPA dermal exposure model, even when uncertainties in its recommended parameter values for TCE are considered but are consistent (p = 0.17) with a 1-compartment model for exposed skin-surface. This study illustrates the power of AMS to facilitate analyses of contaminant biodistribution and uptake kinetics at very low environmental concentrations. Eurther studies could correlate this with toxicity. 

Secondary ion sources (using primary ion beams to sputter solid sample surfaces) are applied not only in SIMS and SNMS, but also for the formation of negative ions in accelerator mass spectrometry (AMS). 

Instrumental layouts and developments in AMS are reviewed by Kutschera.195 Today AMS is the most powerful, sensitive and selective mass spectrometric technique for measuring long-lived radionuclides at the level of natural isotopic abundances (10-16 to 10-12). Accelerator mass spectrometry (AMS) allows uranium isotope ratio measurements with an abundance sensitivity for 236U in the range of l(rlo-10 l2.l98J"... 

Acceleration mass spectrometry (AMS) - The precise measurement of isotopic ratios for very low abundance isotopes is beyond the capability of conventional mass spectrometers. In these cases of isotopes at minute trace levels, some 50 mass spectrometers exist worldwide. The tendetrons used for these types of analyses are derived from Van de Graaff-type particle accelerators. These instruments are based on tandem mass spectrometry. 

Young, G., Ellis, W., Ayrton, J., Hussey, E., and Adamkiewicz, B. (2001). Accelerator mass spectrometry (AMS) Recent experience of its use in a clinical study and the potential future of the technique. Xenobiotica 31 619-632. 

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