Chemistry chemical identification

The Sediment Quality Triad (SQT) is an effects-based conceptual approach that can be used to assess and determine the status of contaminated sediments based on biology (laboratory and/or in situ toxicity tests), chemistry (chemical identification and quantification), and ecology (community structure and/or function). It provides a means for comparing three different lines of evidence (LOE) and arriving at a weight of evidence (WOE) determination regarding the risk posed by contaminated sediments. Effectively, each LOE comprises an independent assessment of hazard combined and integrated, they provide an assessment of risk. 

Ion exchange (qv see also Chromatography) is an important procedure for the separation and chemical identification of curium and higher elements. This technique is selective and rapid and has been the key to the discovery of the transcurium elements, in that the elution order and approximate peak position for the undiscovered elements were predicted with considerable confidence (9). Thus the first experimental observation of the chemical behavior of a new actinide element has often been its ion-exchange behavior—an observation coincident with its identification. Further exploration of the chemistry of the element often depended on the production of larger amounts by this method. Solvent extraction is another useful method for separating and purifying actinide elements. 

Charles D. Coryell, 1912-. Professoi of chemistry at the Massachusetts Institute of Technology. Consultant to the Brookhaven and Oak Ridge National Laboratories of the United States Atomic Energy Commission. The studies of J. A. Marinsky and L. E. Glendenin in his group led to the chemical identification of the missing element 61, which in 1949 was officially named promethium. Dr. Coryell participates actively in the scientific efforts of the Federation of American Scientists and of the United World Federalists toward peace and world stability. 

This chapter provides some insight into the chemistry of a number of commonly used polymeric sorbents. Particular focus is placed on the chemical identification of contaminants typically associated with each of the following types of polymeric sorbents Amberlite XAD resins, Ambersorb XE resins, and PUF. Emphasis is placed on the chemical speciation of solvent-extractable organic contaminants present in a number of these sorbents as received from the manufacturer. Both qualitative and quantitative data on a micrograms-per-gram (parts-per-million) basis are provided as determined by combined gas chromatography-mass spectrometry (GC-MS). 

The Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna, Russia, has recently announced the observation of relatively long-lived isotopes of elements 108, 110, 112, 114, and 116 [63-66] confirming the over 30 years old theoretical prediction of an island of stability of spherical superheavy elements. Due to the half-lives of the observed isotopes in the range of seconds to minutes, chemical investigations of these heaviest elements in the Periodic Table appear now to be feasible. The chemistry of these elements should be extremely interesting due to the predicted dramatic influence of relativistic effects [67], In addition, the chemical identification of the newly discovered superheavy elements is highly desirable as the observed decay chains [63-66] cannot be linked to known nuclides which has been heavily criticized [68,69],... 

Oxides and oxide hydroxides of Tc and Re are typically formed in an O2/H2O containing gas phase. They were extensively studied, mostly using the method of thermochromatography [56-67]. The technique has also been applied to develop Tc and Re generator systems for nuclear medical applications [68,69]. In their works, M. Schadel et al. [70] and R. Eichler et al. [53] studied the oxide and the oxide hydroxide chemistry of trace amounts of Re in an 02/H20-containing system with respect to its suitability for a first gas chemical identification of Bh. They investigated the behavior... 

Yakushev, A.B., Vakatov, V.I., Vasko, V., Lebedev, V.Ya., Timokhin, S.N., Tsyganov, Yu.S., Zvara, I. "On-line Experiments with Short-lived Osmium Isotopes as a Test of the Chemical Identification of the Element 108 - Hassium" In Extended Abstracts of "1st International Conference on Chemistry and Physics of the Transactinide Elements", Seeheim, Germany, 26-30 September 1999, P-M-17. 

Nitrogen chemistry. A very interesting example of rapid gas separation technique in radiochemical work can be found in the study of the chemical identification of 7.3-second, produced by the 0XD(n,p) reaction (200). The target in this study was powdered potassium nitrite pressed... 

Hydrolysed protein preparations have been used to attract various insects. The general subject of insect attractant use both in nature and by man is introduced, with particular reference to the Tephritid family of fruit flies. The work of the Biocommuni-cation Chemistry Research Unit on the identification of the active attractant compounds in the hydrolysed corn protein, Nu-Lure Insect Bait (NLIB) is discussed. Different isolates have been obtained by running simultaneous steam distillation-extractions (SDE) under vacuum and atomospherlc pressure and under basic and acidic conditions. Chemical fractionation of these isolates has also been accomplished. Chemical identification by gas chromatography/mass spectrometry (gc/ms) is discussed. 

At this point, it seems appropriate to summarize the advantages and drawbacks of thermochromatography and isothermal chromatography as the tools for chemical identification and study of chemistry of the very heaviest elements ... 

In recent years, work on the biochemistry and chemistry of the leukotrienes has culminated in the characterization and chemical identification in 1979 of the constituents of SRS-A (slow reacting substance of anaphylaxis) " LTC4, LTD4,... 

RDF descriptors exhibit a series of unique properties that correlate well with the similarity of structure models. Thus, it would be possible to retrieve a similar molecular model from a descriptor database by selecting the most similar descriptor. It sounds strange to use again a database retrieval method to elucidate the structure, and the question lies at hand Why not directly use an infrared spectra database The answer is simple. Spectral library identification is extremely limited with respect to about 28 million chemical compounds reported in the literature and only about 150,000 spectra available in the largest commercial database. However, in most cases scientists work in a well-defined area of structural chemistry. Structure identification can then be restricted to special databases that already exist. The advantage of the prediction of a descriptor and a subsequent search in a descriptor database is that we can enhance the descriptor database easily with any arbitrary compound, whether or not a corresponding spectrum exists. Thus, the structure space can be enhanced arbitrarily, or extrapolated, whereas the spectrum space is limited. 

Chemistry. Chemical analysis methods range all the way from simple to sophisticated. See Chapter 6 under Field Identification. The exact chemical composition is generally not required. The identification method should distinguish the correct material from materials that may have been substituted. For example, a moly (molybdenum) spot test is a chemical color change technique that is sometimes used to distinguish 304 (no moly) from 316 (small percentage of moly) stainless steel. 

There is no doubt that the results from a fragment screening effort influence the decision making of a project. In particular, the use of such data to inspire synthetic chemistry by identification of new binding scaffolds for a particular target is well established. Such information can be used to initiate novel lead series or to optimize chemical leads by replacement of a moiety. Another use of the results from a fragment... 

One name question had thus got an answer but another had arisen. About tantalum no further discussion was needed. But the lighter element - should it be called columbium following Hatchett or niobium following Heinrich Rose. And furthermore were columbium and niobium identical or two different elements An American chemist, J. Lawrence Smith, was contemporary with Rose and had studied with Justus Liebig in the 1840s. He was thus familiar with European chemical hterature and probably with Rose s work on niobium and tantalum. He was professor of chemistry at the university in Louisville 1854-1866 and in 1877 was the second president of the American Chemical Society. In 1877, Smith stated in the American Journal of Science that in 1844 Rose had been of the opinion that he had discovered a new element niobium while Hatchett s columbium was identical with tantalum. However, according to Smith, Rose s further work revealed that niobium was actually identical with columbium. That solved the chemical identification problems. The difficult name question - columbium or niobium - remained to be answered. 

James et al. (33) employed benchtop chemistry for chemical identification of nucleic acids with derivatization by dimethylaminonaphthalene-S-sulfonyl chloride (Dns-CI) formic acid (6%), acetate-ethanoi-ammonium hydroxide, or ethyl acetate-ethanol-ammonium hydroxide was used on a polymide sheet. They used borohydride postlabeling reduction [H ]. 

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