Testing , method expectations

Fire test methods attempt to provide correct information on the fire contribution of a product by exposing a small sample to conditions expected in a fire scenario. Methods can be viewed in two ways the first entails the strategy of the fire test, ignition resistance or low flammabiUty once ignited the second addresses the test specimen, a sample representative of the product or a sample of a material that might be used in the product. Fire science has progressed markedly since the older test methods were developed and it is known that the basis for many of these tests is doubthil. Results from older tests must be used with great care. 

Method vahdation is the demonstration, accompanied by a high degree of assurance, that the test method consistently performs as expected. Vahdation of test methods is especially important when the intended method differs from a compendial or other referenced method and yet is expected to provide equivalent or perhaps better test results. When the reference method is to be used unchanged, no vahdation is necessary. Thus a primary benefit of using compendial methods as written is not needing to do a method vahdation. 

It is necessary to use the test methods presented in this section with some caution. Not all of them have been adequately standardized or applied in a broad sense. They should prove useful for aiding column selection and improving the properties of column packings prepared in the laboratory. It should also be noted that columns may deteriorate with use depending on their treatment. An old coltum of a type that has been shown to perform well in a particular test in the literature may not live up to expectations, due to its altered state. 

Model validation, v - the process of testing a calibration model to determine bias between the estimates from the model and the reference method, and to test the expected agreement between estimates made with the model and the reference method. 

In general terms, the presence of two or more of the structural features indicated above in the same compound will tend to increase the risk. The selection of compound groups and of individually indexed compounds below includes compounds known to have been involved or those with a multiplicity of such structural features which would be expected to be especially susceptible to peroxide formation. A more recent and thorough review of peroxidation risks gives a critical assessment of test methods for peroxides [8],... 

The European Commission has mandated the European Committee for Standardization to establish a validated method of analysis for the determination of OMLs and SMLs. If a product complies with the compositional requirements of the directives, i.e., it is produced from authorized monomers and additives, then it may be tested for any desired application. If it meets the migration requirements, it is acceptable for use in cases covered by that test method. Typical food simulants used in the tests are hot water, acetic acid, ethyl alcohol and olive oil. The choice of an appropriate simulant depends on the type of food expected to come into contact with the packaging. 

The standard astm test method (D-1149-64) for rubber damage includes a test chamber (volume, 0.11-0.14 m ) through which ozonized air flows at a rate greater than 0.6 m/s. Because the residence time of the ozonized air in the test chamber is about 1 s, the ozone may be expected to reach the material in about 0.1 s. A somewhat similar test procedure (aatcc test method 109-1972 ansi L14, 174-1973) is used in testing colorfastness. The ozone generator is usually (but not necessarily) a mercury-vapor resonance lamp with emission lines at 184.9 and 253.7 nm. The 184.9-nm line is absorbed, and two ground-state oxygen atoms are produced ... 

Methods. To observe that corrosion testing in the laboratory frequently fails to predict what happens in real-world environments is to admit that the mechanisms controlling corrosion in such environments are not understood, even at this late date of study. Mechanism-based test methods for monitoring corrosion are needed that will provide reliable and rapid prediction of service life for corrosion-susceptible systems. It is expected that statistical analysis will play a... 

The validation requirements are discussed as they apply to both the sample preparation and sample analysis aspects of a dissolution method. The focus of the discussion in this chapter is on the validation considerations that are unique to a dissolution method. Validation is the assessment of the performance of a defined test method. The result of any successful validation exercise is a comprehensive set of data that will support the suitability of the test method for its intended use. To this end, execution of a validation exercise without a clearly defined plan can lead to many difficulties, including an incomplete or flawed set of validation data. Planning for the validation exercise must include the following determination of what performance characteristics to assess (i.e., strategy), how to assess each characteristic (i.e., experimental), and what minimum standard of performance is expected (i.e., criteria). The preparation of a validation protocol is highly recommended to clearly define the experiments and associated criteria. Validation of a test method must include experiments to assess both the sample preparation (i.e., sample dissolution) and the sample analysis. ICH Q2A [1] provides guidance for the validation characteristics of the dissolution test and is summarized in Table 4.1. 

G. Swift, Expectations for Biodegradation Testing Methods, International Biodegradable Polymer Workshop, Osaka, Japan, Nov. 1993. 

The most suitable physical properties are likely to depend on the particular material, with plastics test methods being used for the harder elastomers (where the title elastomer may not even seem appropriate) and rubber methods for the less hard and more elastic materials. Where thermoplastic elastomers are to compete with conventional rubbers then clearly rubber test methods will be expected. On the other hand, where they are being compared to normal thermoplastics it would seem reasonable to use appropriate plastics test methods. 

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