Isotope detectives

The best labeling system in this regard is isotopic labeling since it involves the minimum change from the standard initiator. Methods based on radiolabeling and stable isotopes detectable by NMR are described in Sections 3.5.4.1 and 3.5.4.2 respectively. 

Isoihamnetin la 323 Isothiazolone, microbiocidal la 45 Isothiocyanates la 75 lb 312 Isothiocyanate anions lb 307 Isotopes, detection limits la 41 Itaconic acid, reduction la 61 lodazide reaction lb 301,303... 

Mukherjee, A. J., Berstan, R., Copley, M. S., Gibson, A. M. and Evershed, R. P. (2007) Compound specific stable carbon isotope detection of pork consumption applied to the British Late Neolithic. Antiquity 81, 743 754. 

Tolgyessy, J., T. Braun, and T. Kyrs. Isotope Detection Analysis, Pergamon, Oxford, 1972. 

Thus, the noble gases are trace elements par excellence. As an example, a not unreasonable value of Xe concentration in a rock is some 10 11 cm3 STP/g (about 3 x 108 atoms/g), or 0.00006ppb. It is nevertheless quite feasible to perform an adequate analysis on a 1-g sample of such a rock, in the sense of a sample to blank ratio in excess of 102, 5-10% uncertainty in absolute abundance, and 1% or less uncertainty in relative abundances of the major isotopes. Detection limits are much lower than this, and for the scarcer isotopes the blank and thus the quantity necessary for analysis are two to three orders of magnitude lower. It is worth noting that the reason why such an experiment is possible is the same reason why noble gases are so scarce in the first place their preference for a gas phase and the ease with which they can be separated from more reactive species. 

The application of in situ hybridization (ISH) has advanced from short lived, non-specific isotopic methods, to very specific, long lived, multiple color fluorescent-ISH probe assays (FISH). Improvements in the optics, filter technology, microscopes, cameras, and data handling by software, have allowed for a cost effective FISH setup to be within reach of most researchers. The application of mFISH (multiplex-FISH), coupled to the advances in digital imaging microscopy, have vastly improved the capabilities for non-isotopic detection and analysis of multiple nucleic acid sequences in chromosomes and genes (1). 

Every radioactive isotope detected in groundwater serves as a potential tool for dating. The half-life of 36C1 — 3 x 105 years—is especially promising because it fills in a most important time span, that is, beyond the limits of groundwater dating by radiocarbon. 

Wilson et al. (1972) have recently reported the first positive 1SN isotopic detection in an astronomical source. They observed in the Orion molecular cloud the J = 2 -> 1 transitions of the rare hydrogen cyanide isotopic species H13C14N and H12C15N whose rest frequencies are 172677.7 MHz and 172108.1 MHz, respectively (Winnewisser et al., 1971). For these two molecules and in almost all the other isotopic abundance determinations, which can presently be given only with large error margins ( 20 %—50%), the isotopic ratios are found to have essentially terrestrial values. 

Long-lived cosmogenic isotopes detected with accelerator mass spectrometry... 

When using two lasers and applying two-photon spectroscopy, only those atoms that do not have a velocity component in the observation direction will undergo LEI. Then the absorption signals become very narrow (Doppler-free spectroscopy). This enhances the selectivity and the power of detection, however, it also makes isotope detection possible. Uranium isotopic ratios can thus be detected, similarly to with atomic fluorescence [673] or diode laser AAS. Thus for dedicated applications a real alternative to isotope ratio measurements with mass spectrometry is available. 

By modifying the isotopic ratio of this element or one of the atoms of the molecule, either with a radio-element (whose activity is measured in becquerels) or with a stable isotope (detection by mass spectrometry or NMR). These are called isotopic analyses. 

Beaver,D.R. (1995) Anewnon isotopic detection system for immunoassays. Nature, 377, 758 760. 

Zn Atomic Number, Symbol isolopic Abundance Most Abundant Isotope Detection LImtt Ranges Q tO.1- 1 ppl Q 1-10 ppl... 

Plutonium is a radioactive element produced by neutron capture and beta decay of uranium-238 (or other elements), both naturally (in minuscule amounts) and as a result of human activities. Plutonium is found in the environment in the form of several isotopes. The source of plutonium can be traced based on the isotope or isotopes detected in a sample. Plutonium is found naturally in uranium-rich ores in concentrations of one part per 1011 parts uranium (i.e., 1x10-11 kg plutonium/kg uranium) (Leonard 1980). 

Chan WCW, Niw S. (1998) Quantum dot bio-conjugates for ultrasensitive non-isotopic detection. Science. 281 2016-2018... 

A third case of historical isotope detective work concerns the Pueblo ancestor people (commonly called the Anasazi), who lived in what is now northwestern New Mexico between a.d. 900 and 1150. The center of their civilization, Chaco Canyon, was a thriving cultural center boasting dwellings made of hand-hewn sandstone and more than 200,000 logs. The sources of the logs... 

Singer, R. H., Lawrence, J. B., and Villnave, C. (1986) Optimization of in situ hybridization using isotopic and non-isotopic detection methods Biotechniques 4, 230-250... 

Easy speciation and isotope detection have been identified as playing important roles in optimizing the production of superconducting NbsSn wires by heating a composite of bronze and niobium filaments. Application of TOF-LMMS has provided evidence of the out-diffusion and accumulation of phosphorous, inhibiting Nb3Sn formation when tin diffuses inward. The preferential incorporation of the lower tin isotopes in the NbsSn layer has confirmed the process to be driven by diffusion. The semiconductor industry has used TOF-LMMS to verify the lateral diffusion of dopants, e.g., boron in tantalum and cobalt silicide ruimers only 3 pm wide. Another application is the identification of microscopic residues left on integrated circuits after removal of the photoresist. 

When the surface of a solid is bombarded by energetic primary particles, usually, electrons, ions, neutrals, or photons, and secondary particles are emitted. The secondary particles are mainly electrons, neutral species, atoms or molecules, atomic and cluster ions. The majority of secondary particles are neutral species. The secondary ion mass spectrometry (SIMS) is a kind of mass spectrometry, where only secondary ions are detected and analyzed by the mass spectrometer. The process yields a mass spectrum of a surface and thus the method enables a detailed chemical analysis of a surface or solid. SIMS is such a powerful technique of surface analysis and microstructural characterization of solids that a very low primary particle flux density of 1 nA/cm or even less can generate spectral data in a timescale, which is very short compared to the lifetime of the surface layer. SIMS is particularly well known for its outstanding sensitivity of chemical and isotopic detection. Quantitative or semiquantitative analysis can... 

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