General principles and concepts

EAL and Eurolab have a Permanent Liaison Group (PLG), which is a forum where EAL and Eurolab are discussing matters of mutual interest. The PLG consists of five members from each organization. 

This document has been prepared in the PLG and endorsed by both organizations. 

The document is intended to give general views on certain issues related to the validation of test methods and should be seen as a common understanding and position of EAL and Eurolab. In order to define and describe the activities behind the concept Validation of test methods more detailed guidance documents are needed. This document should be seen as a basis for such guidance documents. 

The definition used for validation in the ISO standard 8402 is confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use are fulfilled . This definition gives the impression of confined and well-defined (exact) operations. Test methods are normally developed for an intended application range. The reference to particular requirements must in many cases be interpreted in a flexible way as the requirements can be of general nature. 

Both standardized and non-standar-dized test methods are covered. They can be exact or associated with large uncertainties. Even novel test methods will be considered. The validation of a test method becomes in this context a way of demonstrating that the method is fit for its intended purpose. The fitness for purpose includes an assessment and a balancing of technological possibilities, risks and costs. 

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European cooperation for Accreditation of Laboratories (EAL) (1997) Validation of test methods. General principles and concepts, EAl-PH, 1st edn. European cooperation for Accreditation (EA)... 

Validation of test methods. General principles and concepts 141... 

Chapter 3 introduced the basic concepts of scaleup for tubular reactors. The theory developed in this chapter allows scaleup of laminar flow reactors on a more substantive basis. Model-based scaleup supposes that the reactor is reasonably well understood at the pilot scale and that a model of the proposed plant-scale reactor predicts performance that is acceptable, although possibly worse than that achieved in the pilot reactor. So be it. If you trust the model, go for it. The alternative is blind scaleup, where the pilot reactor produces good product and where the scaleup is based on general principles and high hopes. There are situations where blind scaleup is the best choice based on business considerations but given your druthers, go for model-based scaleup. 

Contemporary s Tithetic chemists know detailed information about molecular structures and use sophisticated computer programs to simulate a s Tithesis before trying it in the laboratory. Nevertheless, designing a chemical synthesis requires creativity and a thorough understanding of molecular structure and reactivity. No matter how complex, every chemical synthesis is built on the principles and concepts of general chemistry. One such principle is that quantitative relationships connect the amounts of materials consumed and the amounts of products formed in a chemical reaction. We can use these relationships to calculate the amounts of materials needed to make a desired amount of product and to analyze the efficiency of a chemical synthesis. The quantitative description of chemical reactions is the focus of Chapter 4. 

The student s first exposure to biochemistry is probably a lecture course accompanied by the reading of a general textbook of biochemistry. By providing an in-depth survey of biochemistry, textbooks allow students to build a strong foundation of important principles and concepts. By the time most books are in print, the information is 1 to 2 years old, but textbooks still should be considered the starting point for mastery of the fundamentals of biochemistry. 

This Report is concerned with classification of hazardous waste for purposes of disposal. However, the principles and concepts embodied in the waste classification system could be applied in classifying hazardous materials for any other purpose. The classification system is intended to be applied to hazardous waste prior to disposal. It is not intended to be applied to screening or ranking of contaminated sites, including existing hazardous waste disposal sites, because these activities involve site-specific considerations that cannot be included in a generally applicable waste classification system. However, any wastes exhumed from contaminated sites that then require disposal would be included in the waste classification system. 

The principles and concepts of TQM have been formalized into a quality management process, as illustrated in Figure 19-3. The traditional framework for managing quality in a healthcare laboratory has emphasized the establishment of quality laboratory processes (QLPs), QC, and quality assessment (QA). A QLP includes analytical processes and the general poHcies, practices, and procedures that define how all aspects of the work get done. QC emphasizes statistical control procedures but also includes nonstatistical check procedures, such as linearity checks, reagent and standard checks, and temperature monitors. QA, as currently applied, is primarily concerned with broader measures and monitors of laboratory performance, such as turnaround time, specimen identification, patient identification, and test utility. Quality assessment is the proper name for diese activities rather than quality assurance. Measuring performance does not by itself improve performance and often does not detect problems in time to prevent harmful effects. Quality... 

The construction of MO diagrams under the guidance of the general principles and symmetry restrictions that we have outlined can lead to useful insights into molecular structure. Now we want to consider how these concepts can be related to reactivity. In valence bond terminology, structure is related to reactivity in terms of the electronic nature of the substituents. The impact of polar and resonance effects on the electron... 

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