Specific characteristics, measuring

Rowell and co-workers [62-64] have developed an electrophoretic fingerprint to uniquely characterize the properties of charged colloidal particles. They present contour diagrams of the electrophoretic mobility as a function of the suspension pH and specific conductance, pX. These fingerprints illustrate anomalies and specific characteristics of the charged colloidal surface. A more sophisticated electroacoustic measurement provides the particle size distribution and potential in a polydisperse suspension. Not limited to dilute suspensions, in this experiment, one characterizes the sonic waves generated by the motion of particles in an alternating electric field. O Brien and co-workers have an excellent review of this technique [65]. 

Measurement of exposure can be made by determining levels of toxic chemicals in human serum or tissue if the chemicals of concern persist in tissue or if the exposure is recent. For most situations, neither of these conditions is met. As a result, most assessments of exposure depend primarily on chemical measurements in environmental media coupled with semi-quantitative assessments of environmental pathways. However, when measurements in human tissue are possible, valuable exposure information can be obtained, subject to the same limitations cited above for environmental measurement methodology. Interpretation of tissue concentration data is dependent on knowledge of the absorption, excretion, metabolism, and tissue specificity characteristics for the chemical under study. The toxic hazard posed by a particular chemical will depend critically upon the concentration achieved at particular target organ sites. This, in turn, depends upon rates of absorption, transport, and metabolic alteration. Metabolic alterations can involve either partial inactivation of toxic material or conversion to chemicals with increased or differing toxic properties. 

Suspensions are generally evaluated with respect to their particle size, electrokinetic properties (zeta potential), and rheological characteristics. A detailed discussion on the methods/techniques and relevant instrumentation is given in Sec. VII. A number of evaluating methods done specifically with suspension dosage forms, such as sedimentation volume, redispersibility, and specific gravity measurements, will be treated in this section. 

The word protein describes only one type of polymer involving mainly a-amino acids and yet it includes many thousands of different molecules. It is possible to measure the total protein content of a sample despite the fact that relatively simple preparative techniques may be capable of demonstrating the presence of different proteins. However, if interest lies in only one of these proteins, then a measure of the total protein content would be completely inappropriate. Methods for the quantitation of proteins are either suitable for all proteins or designed to measure individual proteins. Such specific methods may depend on either a preparative stage in the analysis or the use of a specific characteristic of the protein in question. 

The measurement of natural radioactivity with a y-ray detector determined the activity coefficient (the quantity of y-rays emitted), whieh is a specific characteristic of each type of sediment or rock. Specifically, a high y-ray count indicates the unmistakable presence of a elay matrix and thus constitutes useful information for the synthesized, integrated interpretation of this and other measurements performed. 

The vegetation used to extract toxic metals may pose a risk to animals that consume these plants. Animal consumption of process plants could also result in harmful metals working their way up the food chain. Hyperaccumulation is a much slower process than most chemical and physical technologies, and its performance is typically measured in months or years. Technology effectiveness is limited by root growth thus, wastes must be relatively close to the surface. In addition, the toxicity of the targeted contaminants and other site-specific characteristics such as pH, soil characteristics, nutrient content, and water availability can impact technology performance. 

Polarimetric detectors have demonstrated significant advantages for identification of optically active drug residues because optical activity is an extremely rare characteristic usually associated with biological activity. Specific rotation measurements on drug residues as they elute from the LC column have the potential to identify closely related structural analogues even when present in a compli-... 

GIS may also be used to assess the site-specific bioavailability of toxicants and their ecological risks. For example, Prusha and Clements (2004) related metal concentrations in the lotic insect Arctopsyche grandis to physicochemical characteristics measured in 16 streams. GIS was used to calculate landscape attributes in... 

For a dominant complex in a solution precise determinations of the intramolecular distances can usually be made. Derivations of coordination numbers and geometries will depend on the specific characteristics of the system investigated. Although solution X-ray diffraction measurements have been primarily concerned with the structures of metal aqua ions, other ligands and nonaqueous solutions often offer more favorable conditions for structure determinations of complexes. 

Numerous factors influence the bioaccumulation of uranium, such as the chemical and physical form of the uranium the season of the year and other climatic factors such as temperature, age of the organism, specific tissue or organs involved and the specific characteristics of the local ecosystem, such as total suspended and dissolved solids. Bioconcentration factors for uranium have been measured by several investigators in various aquatic organisms. Mahon (1982) measured bioconcentration factors of 1,576 and 459 in algae and plankton, respectively. Horikoshi et al. (1981) determined bioconcentration factors in several species of bacteria that ranged from 2,794 to 354,000. However, bioconcentration by the bacteria represented adsorption onto the cell surfaces of the bacteria rather than true biological uptake. 

In the Grand Accelerateur National dTons Lourds (GANIL, Caen, France) facility, ion beams are delivered in order to understand the specific characteristics of SHI-matter interactions. In particular, polymers are investigated. Infrared spectroscopy is a very powerful tool to characterize organic species in general and polymers in particular FT-IR spectra have been recorded in GANIL since 1994 in order to understand the specificities of SHI-polymers behavior. The first studies were ex situ measurements. Since 2003, SHI irradiations have been analyzed by means of in situ FT-IR spectroscopy. 

Validation is the process of measuring the performance of a previously developed quantitative method. The characteristics measured to assess performance are defined and explained in detail later in this chapter. Typically, for a quantitative method the characteristics of specificity, accuracy, precision, and linearity are measured. The range of the method can be defined, or verified, by the region where the aforementioned characteristics are acceptable. Although their determination is more appropriately a development task, the characteristics of robustness, limit of detection, and limit of quantitation can also be verified during validation. 

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