Chemical quantitative

The unique appearance of an infrared spectrum has resulted in the extensive use of infrared spectrometry to characterize such materials as natural products, polymers, detergents, lubricants, fats and resins. It is of particular value to the petroleum and polymer industries, to drug manufacturers and to producers of organic chemicals. Quantitative applications include the quality control of additives in fuel and lubricant blends and to assess the extent of chemical changes in various products due to ageing and use. Non-dispersive infrared analysers are used to monitor gas streams in industrial processes and atmospheric pollution. The instruments are generally portable and robust, consisting only of a radiation source, reference and sample cells and a detector filled with the gas which is to be monitored. 

The quantitation of a protein that has a specific biological function, a hormone, for instance, may not give a true indication of its biological activity owing to the inactivation of some of the protein. For proteins that have definite biological functions the choice is between chemical quantitation and bioassays. For this reason the catalytic activity of an enzyme is more frequently measured than is its protein concentration. 

Many important decisbns are based on the results of chemical quantitative analysis... 

Modern scientific tools like the so-called odour-activity value (OAV) concept were developed to unravel the quantitative and qualitative pattern of individual chemicals. Quantitation is achieved in an extremely accurate way by means of isotope dilution analysis. 

W. M. Manger, Chemical Quantitation of Epinephrine and Norepinephrine in Plasma. Charles C. Thomas, Springfield, 111., 1959. 

Ultimately, all quantitative analytical methods rely upon standards, whose composition is determined by the classical techniques of wet chemical quantitative analysis. Obviously, the preferred techniques for analyzing art objects are nondestructive, such as x-ray fluorescence, neutron activation, electron microprobe (both dispersive and nondispersive techniques), and so forth. Emission spectrographic analysis is not suit-... 

Campo, E., Ferreira, V., Escudero, A., Marques, J. C., and Cacho, J. (2006). Quantitative gas chromatography-olfactometry and chemical quantitative study of the aroma of four Madeira wines. Anal. Chim. Acta 563,180-187. 

Although fluorescence has been a major hindrance for the use of Raman spectroscopy in biology, Shope and colleagues [116] clearly showed that the narrow Raman peaks were distinct from the broad features of fluorescence and proposed the use of full widths at half-height of the peaks for chemical quantitation from Raman spectra. Shope et al. [116] used a least squares fit to analyse the Raman spectra for quantification of the production of ethanol during the... 

Environmental fate models make use of chemical properties to describe transfer, partitioning, and degradation (Mackay et al. 1992a Cahill et al. 2003). For organic chemicals, quantitative structure-property relationships (QSPRs) may be used to predict partitioning from physical-chemical properties, such as Kow and Kov Such properties may also allow for a prediction of the transfer of chemicals between compartments. Recently, some successful attempts have also been made to predict persistency of chemicals (Raymond et al. 2001), although this mainly concerns... 

The ability of certain soils to sorb the chemical strongly is important in analyzing residues of the chemical in soil. A procedure must be developed which will recover the chemical quantitatively from any soil. Table VII compares extraction from two soils, soil 3 which saturates with 4-amino-3,5,6-trichloropicolinic acid quickly and soil Bi which shows the slow takeup phenomenon. It is apparent that soil Bi, incubated 2 hours, holds the chemical more firmly than soil 3, incubated 5 days, but that hot water will remove most of the chemical from both soils. When soil Bi has been incubated for 28 days, removal of chemical was only 78.7% after three water washes, but further extraction with NaOH increased the recovery to over 99%. Several mild methods of extraction are compared in Table VIII. The same experimental techniques were used here but, instead of determining the extracted 4-amino-3,5,6-trichloropicolinic acid, the washed soil was assayed. A 50-mg. portion of dried, ground soil was suspended in a silica gel medium for scintillation counting and... 

G4. Gallop, P. M., Fliickiger, R., Hanneken, A., Mininsohn, M. M., and Gabbay, K. H., Chemical quantitation of hemoglobin glycosylation fluorometric detection of formaldehyde released upon periodate oxidation of glycoglobin. Anal. Biochem. 117, 427-432 (1981). 

Both high and low resolution NMR are used for quantitative analyses of mixtures, quality control of both incoming raw materials and finished products, determination of percent purity of pharmaceuticals and chemicals, quantitative determination of fat and water in vivo in animals, and many other applications. 

UV-visible absorption Chemical quantitative analysis Native ... 

Detection limit n. Of chemical quantitative analyses, the least quantity of concentration of the substance being sought that can be detected with a stated level of confidence. 

These results provide the following information for the tested chemicals quantitative characteristics of accumulation, certain aspects of toxic dynamics, substantiation of selected tests and doses for chronic experimentation, prediction of chronic effects, and evaluation of the possible values of maximum acceptable concentrations (using the parameters of acute toxicity and accumulation, based on known corresponding correlations). 

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