Detection chemical

W. Ruch, ed.. Chemical Detection of Gaseous Pollutants, Ann Arbor Science PubHshers, Inc., Ann Arbor, Mich., 1966. 

Detection. Many people can detect hydrogen cyanide by odor or taste sensation at the 1 ppm concentration in air, most at 5 ppm, but HCN does not have an offensive odor and a few people cannot smell it even at toxic levels. Anyone planning to work with hydrogen cyanide should be checked with a sniff test employing a known safe concentration. This test should be given periodically. Several chemical detection and warning methods can be employed. The most rehable are modem, electronic monitors based on electrolytes that react with hydrogen cyanide. 

A number of other chemicals suspected of having endocrine disrupting potential also occur at high levels in the tissues of marine mammals. For example, tribiityltin compounds are present in the tissues of the Steller sea lion (Eumetopias juhatus) from Hokaido, Japan, and in stranded bottlenose dolphins (Tursiops truncatus) found along the US Atlantic and Gulf coasts.Additional chemicals detected include PAHs, toxaphene and chlordane. ... 

In spite of numerous advances in the field of detection there are not and never have been any genuinely substance-specific chemical detection reactions. This means that, unlike the spectrometric methods, the methods of detection normally employed in chromatography cannot be employed for an unequivocal identification of compounds, they can only provide more or less definite indications for the characterization of the separated substances. Universal reagents are usually employed for a first analysis of the separation of samples of unknowns. This is then followed by the use of group-specific reagents. The more individual the pieces of information that can be provided from various sources for a presumed substance the more certainly is its presence indicated. However, all this evidence remains indicative it is not a confirmation of identity. 

Physical and Chemical Detection Methods (in several parts, parts lb and Ic in preparation)... 

The recent rise in the use of expolosives in terrorist activity poses new challenges to industry and law enforcement. This challenge is being met by the use of sophisticated chemical detection devices to screen for bombs and more rigorous explosive inventory safeguards and controls. Plans have also been proposed to tag explosives with isotopes to make them easier to trace if misused. 

The identification of a molecular structure from a mass spectrum requires good chemical detective work. Let s see how that is done by trying to identify a simple compound,... 

Methyl parathion is listed in the HazDat database of chemicals detected in surface water or groundwater atNPL sites. 

The protein from D. desulfuricans has been characterized by Mbss-bauer and EPR spectroscopy 224). The enzyme has a molecular mass of approximately 150 kDa (three different subunits 88, 29, and 16 kDa) and contains three different types of redox-active centers four c-type hemes, nonheme iron arranged as two [4Fe-4S] centers, and a molybdopterin site (Mo-bound to two MGD). Selenium was also chemically detected. The enzyme specific activity is 78 units per mg of protein. 

Physical and Chemical Detection Methods Activation Reactions, Reagent Sequences, Reagents II... 

Today we work confidently with the rows and columns of the periodic table. Yet less than 150 years ago, only about half of all elements known today had been discovered, and these presented a bewildering collection of chemical and physical properties. The discoveiy of the patterns that underlie this apparent randomness is a tale of inspired chemical detective work. 

M. A., Towards integration of chemical detection for liquid phase microchannel reactors, in Proceedings of the 4th International Conference on MicroreacUon Technology, IMRET 4, 5-9 March 2000, pp. 461 66, AIChE Topical Conf. Proc., Atlanta, GA (2000). 

The DBPCAN database contains predicted estimates of carcinogenic potential for 209 chemicals detected in finished drinking water samples having undergone water disinfection treatment. 

Specific Chemical Detection Methods Used for Various Lipids Separated by TLC... 

Mass spectrometry for enhanced trace chemical detection,3... 

Discontinuous chemical-detection systems do not provide a signal that is continuous in time, but rather cycle rapidly through a series of phases such as sample collection, preconcentration, separation, and detection in such a way that the overall system is capable of providing a detection report every minute or so. Examples of such systems include ion mobility spectrometers, mass spectrometers, and chromatography-based systems. Many technologies are possible candidates for each of the different phases.2... 

H. Jork, W. Funk, W. Fischer and H. Wimmer, Thin-layer Chromatography, Vol. Ia, Physical and Chemical Detection Methods Fundamentals, Reagents, VCH, Weinheim (1990). 

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