Intended use

The choice of a chromatographic method may be dependent on the intended use. The appropriate method when the intent is to establish a general screen for inhalant abuse may be very different from the method chosen to monitor administration of a particular anesthetic or exposure to industrial chemicals in the workplace. Likewise, forensic applications may vary from a general screen to post-mortem quantitation of particular suspected VOCs in blood and tissues. The number of methods developed for specific purposes (or compounds) is beyond the scope of this chapter, but it is hoped that the information provided will assist the analyst in finding or adapting chromatographic methods suitable for their particular situation. 

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At the start of the development, it had been intended use an expert system shell to implement this tool, however, after careful consideration, it was concluded that this was not the optimum strategy. An examination procedure can be considered as consisting of two parts fixed documentary information and variable parameters. For the fixed documentary information, a hypertext-like browser can be incorporated to provide point-and-click navigation through the standard. For the variable parameters, such as probe scanning paths, the decisions involved are too complex to be easily specified in a set of rules. Therefore a software module was developed to perfonn calculations on 3D geometric models, created fi om templates scaled by the user. 

Where a Member State ascertains tliat a product, bearing the CE-marking and used in accordance with its intended use, is liable to endanger the safety of persons or health, it shall take all appropriate measures to withdraw such a product from the market. That Member State shall immediately Inform the Commission which is obliged to investigate whether or not the measure is justified. Where the Commission considers that the measure is justified, it shall immediately inform the Member State which took the initiative and also the other Member States. This entails that the other Member States must also take action against the product concerned. That latter disposition is referred to as the safeguard clause. 

Computational chemistry is used in a number of different ways. One particularly important way is to model a molecular system prior to synthesizing that molecule in the laboratory. Although computational models may not be perfect, they are often good enough to rule out 90% of possible compounds as being unsuitable for their intended use. This is very useful information because syn-... 

The type of initiator utilized for a solution polymerization depends on several factors, including the solubiUty of the initiator, the rate of decomposition of the initiator, and the intended use of the polymeric product. The amount of initiator used may vary from a few hundredths to several percent of the monomer weight. As the amount of initiator is decreased, the molecular weight of the polymer is increased as a result of initiating fewer polymer chains per unit weight of monomer, and thus the initiator concentration is often used to control molecular weight. Organic peroxides, hydroperoxides, and azo compounds are the initiators of choice for the preparations of most acryUc solution polymers and copolymers. 

For staple, the heat-treated filaments in the form of tow are cut to prescribed lengths and then acetalized to develop crimp on individual cut fibers. A suitable finish is selected from conventional ones and appHed to the acetalized fibers to improve their spinnabiUty and other properties required for the intended use. 

Clearly, the intended use of a collection item is extremely important to determining the acceptabiHty of a treatment. The degree to which a treatment affects appearance is obviously of the greatest importance for an art object. On the other hand, in natural history collections the collections serve as research resources above all. The effect a preservation or conservation treatment has on these research appHcations is the main consideration. Collections of art, archaeology, history, science, technology, books, archival materials, etc, all have their own values in terms of balance between preservation needs and collections use, and these values are, moreover, constantly subject to reevaluation and change. 

The flavor chemist is responsible for the basic knowledge of sensory and appHcation properties of each of this large number of raw materials the large number of possible combinations of these items to produce specifically flavored finished compounds is readily apparent. It is not uncommon to develop a flavor that combines essential oils, plant extractive, fmit juices, and synthetics. The choice of materials depends on type of product, conditions of manufacture, labeling, and intended use. 

Countries that use a positive Hst, eg, Japan, Switzerland, the former Soviet Union, and the United States, Hst ak substances akowable in flavor and foods any material not Hsted is not akowable. Any material included on a positive Hst is considered safe for its intended use. This system works wek only if there is a specific procedure to akow for the addition of new materials. In the United States there is the Food Additive Petition and the GRAS route. No new material can be used in flavor or foods unless it undergoes one of these two procedures. This assures that any new technology can be added and used after it is reviewed for safety. 

According to the U.S. Code of Federal Regulations, food additives may be defined as "substances. .. the intended use of which results or may reasonably be expected to result, directly or indirectly, either in their becoming a component of food or otherwise affecting the characteristics of food" (1). Canada and the European Community have adopted similar definitions. According to this broad definition, a food additive is synonymous to a food ingredient. In practice, however, the word additive is limited to substances that are used in small quantities. 

Re OPe . The final step in the chemical processing of rare earths depends on the intended use of the product. Rare-earth chlorides, usually electrolytically reduced to the metallic form for use in metallurgy, are obtained by crystallisation of aqueous chloride solutions. Rare-earth fluorides, used for electrolytic or metaHothermic reduction, are obtained by precipitation with hydrofluoric acid. Rare-earth oxides are obtained by firing hydroxides, carbonates or oxalates, first precipitated from the aqueous solution, at 900°C. 

Chemical binders are appHed to webs in amounts ranging from about 5 to 60 wt %. In some instances when clays (qv) or other weight additives ate included, add-on levels can approach or even exceed the weight of the web. Waterborne binders ate appHed by spray, saturation, print, and foam methods. A general objective of each method is to apply the binder material in a manner sufficient to interlock the fibers and provide chemical and mechanical properties sufficient for the intended use of the fabfic. 

A number of other words that have traditionally been used in the petroleum industry are difficult to define precisely. These refer pardy to specific hoiling ranges, but also to certain intended uses. Thus, gasoline boils lower than naphtha, and kerosenes generally higher, but these terms are applied to products that ate intended as fuels, rather than as solvents. 

Sepa.ra.tion of Plutonium. The principal problem in the purification of metallic plutonium is the separation of a small amount of plutonium (ca 200—900 ppm) from large amounts of uranium, which contain intensely radioactive fission products. The plutonium yield or recovery must be high and the plutonium relatively pure with respect to fission products and light elements, such as lithium, beryUium, or boron. The purity required depends on the intended use for the plutonium. The high yield requirement is imposed by the price or value of the metal and by industrial health considerations, which require extremely low effluent concentrations. 

Chemical charge, Hquor composition, time of heatup, and time at temperature of reaction are all functions of the wood species or species mix being digested and the intended use of the pulp. A typical set of conditions for southern pine chips in the production of bleachable-grade pulp for fine papers is active alkaH, 18% sulfidity, 25% and Hquor-to-wood ratio, 4 1. Time of heatup is 90 min to 170°C time at temperature of reaction, 90 min at 170°C. Hardwoods require less vigorous conditions primarily because of the lower initial lignin content. 

The acquisition and processing of oil that has become unsuitable for its intended use in order to regain useful material. 

Unless otherwise exempt, a firm must submit a premarket notification, also called a 510(k), to the PDA 90 days before it intends to market a device for the first time (17). The 510(k) submission must contain sufficient information to show that the device in question is substantially equivalent to a legally marketed device for a particular intended use. This notification is also required for a product when there is a change or modification to a product that may significantly affect the safety or effectiveness of the device, or when there is a significant change or modification to the intended use of the device. 

An ingredient used in food prior to January 1, 1958 can be considered GRAS under the conditions of its intended use based on common use in food. PDA prior approval generally is not necessary. A post-1958 food ingredient that is generally recognized by qualified experts as safe, under the conditions of its intended use based on scientific tests, is GRAS by definition and therefore is not a food additive and does not require PDA approval prior to use. 

Any substance that is not GRAS or sanctioned by use prior to 1958 (prior sanctioned) is considered a food additive. The Act prohibits the marketing of a food additive unless PDA has pubHshed a regulation that approves the intended use of the substance (22). A food additive is deemed unsafe if it is used without an approving regulation a food is deemed adulterated if it is, bears, or contains an unapproved food additive. 

Animal dmg controls are similar to those for human dmgs. The sponsor of a new animal dmg must demonstrate both safety and effectiveness of the dmg for a particular intended use before a New Animal Dmg AppHcation (NADA) is approved (24). Manufacturers of generic animal dmgs may submit Abbreviated New Animal Dmg AppHcations (ANADAs), which are comparable to abbreviated new dmg appHcations submitted by manufacturers of human generic dmgs. 

Toxicity. The U.S. Eood and Dmg Administration regards common salt, ie, NaCl, as GRAS for its intended use as a food additive. Oral toxicity for mammals is reported in mg/kg (16) for humans, TD qI 12,357 23D-C (daily-continuous) for mice, LD qI 4000 for rats, LD qI 3000 and for rabbits, LD qI 8000. TD q and LD q are lowest level toxic and lethal dosages, respectively. 

Provisions must be made for allowing residues of the stefilant absorbed by the product to dissipate by using aeration cabinets that have forced-air circulation at elevated temperatures. The amount of remaining absorbed stefilant should be determined before releasing the sterilized articles. If, as in the case of hospital sterilization, such studies are not feasible, the recommendations of the manufacturers of the articles sterilized or of the aeration equipment should be obtained. The permissible residue concentrations are 10—250 ppm, depending on the type of article and on its intended use. 

Processes that are essentially modifications of laboratory methods and that allow operation on a larger scale are used for commercial preparation of vinyhdene chloride polymers. The intended use dictates the polymer characteristics and, to some extent, the method of manufacture. Emulsion polymerization and suspension polymerization are the preferred industrial processes. Either process is carried out in a closed, stirred reactor, which should be glass-lined and jacketed for heating and cooling. The reactor must be purged of oxygen, and the water and monomer must be free of metallic impurities to prevent an adverse effect on the thermal stabiUty of the polymer. 

Stream standards are usually based on a system of classifying the water quaUty based on the intended use of the water. 

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