International Standardization Organization chemical methods

All test methods adopted or under development by national or international standard organizations (e.g., OECD, ISO...) are suitable for WASTOXHAS. However, the choice of endpoints to be evaluated, among a large number now available, and their quantification methods, are directly related to criteria defining limit values. Examples of different chemical limits can be found in Lapa et al. (2002b). 

Commercial trade in chemical celluloses is assisted by the definition of standard methods of analysis. Extensive collections of quality-defining protocols have been assembled by ISO, the International Standards Organization ASTM, the American Society for Testing Materials TAPPI, the Technical Association of the Pulp and Paper Industry (of USA) DIN (German Industrial Norms) and many others. 

International Standards Organization, Chemistry—Layouts for Standards, Part 2, Methods of Chemical Analysis, ISO 78-2 1999, Geneva, 1999. 

ISO (1999), Chemistry—Layouts for standards—Part 2 Methods of chemical analysis, 78—2 (Geneva International Organization for Standardization). 

NBS is not a regulatory agency. It does not mandate or enforce standards, but it does provide the technical basis for the selection and application of standards by other agencies and by domestic and international voluntary standards organizations (10). NBS ensures that physical and chemical measurements within the United States can be traced to a consistent set of standards, reference methods, and reference materials that also are compatible with those used to regulate international trade. 

Peak positions in an XPS spectrum are likely to be affected by spectrometer conditions and the sample surface. Before XPS peak identification, we often need to calibrate the binding energy. Calibration is particularly important for samples with poor electrical conductivity. Calibration can be done with an internal standard that has a peak that shows little or no chemical shift, for example, elemental Si. The most common method is use of the C Is peak at 285 eV from carbon adsorbed on the sample surface. The carbon from organic debris (as C—H or C-C) in air is found on all samples exposed to the environment. The peaks of core level binding energies as listed in Table 7.1 are sufficiently unique for element identification. 

There are no internationally standard assay methods for industrial enzymes and the definition of enzyme activity unit is also different for each enzyme. The activity of industrial enzymes is shown by various methods depending on manufacturers. For instance, commercial lipase activities are measured by the hydrolysis of olive oil under the various conditions and these figures are not comparable with each other. When customers apply these biocatalysts for chemical synthesis in organic solvents, these figure are sometimes reliable, and sometimes not. Users should not judge commercial enzymes based only on price and the activity shown in the table the manufacturer provides. Enzymes should be evaluated based on their practical performance under the conditions used. Most users of biotransformation are not experts in measuring enzyme activity, so the establishment of an assay method and practice are essential if one is to optimize the performance of enzymes. 

Off line thermochemolysis is also possible at much lower temperatures (250°C). " Thermochemolysis reactions with TMAH can be conducted in a sealed glass ampoule thus allowing for more controlled conditions, where internal standards can be added to provide quantitative measurement. Off line thermochemolysis gives similar results as the more time consuming chemical degradation methods used in the analysis of organic matter. ... 

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