Testing methods design issues

The second aspect of quahty documentation is to detail how the work processes referred to in the manual are performed. The QA unit is often the organization responsible for issuing a set of procedures designed to assure conformance to the appropriate standards or to company poHcy. The procedures, often called standard operation procedures (SOP) or quahty operating procedures (QOP), should include such topics as customer complaints, audit protocols, stabihty testing, preparation of COAs, test method vahdation, etc. 

Europe s controversy over soft PVC toys looks set to continue after EU health experts rejected the best available method for assessing the dangers to children. The so-called Dutch migration test was designed to mimic the way phthalate softeners leak out of PVC when it is sucked or chewed. Manufacturers had hoped the EU s Scientific Committee for Toxicity, Ecotoxicity and the Environment would accept the method as a standard test for phthalate migration, allowing it to be used across the EU, but the committee ruled that the Dutch test was unreliable. It also rejected a similar test developed in the UK, and issued a list of changes that would have to be made before either... 

Several documents describe the requirements for viral clearance studies. The ICH guidance on viral safety evaluation provides information on the design of viral clearance studies and their interpretation [37], Unlike most other aspects of process validation, viral clearance cannot be performed at full scale. There are several reasons for this. Direct testing methods may not detect low concentrations of virus, which requires that viruses be spiked into the feedstream. Assays may detect only known viruses, and they may also fail to detect variants. Worker safety is another issue that necessitates the need to perform the validation at a small scale. Scaling down is addressed in the ICH guidelines and in the literature [38,39]. 

Toxic effects of all classes of contaminants including metals, pesticides, and organic substances can be captured with the pT-method, as long as the test battery employed reflects a sufficiently wide spectrum of sensitivity. Furthermore, test organisms in a battery should be representative of aquatic biota. The composition of test batteries can be varied according to different aquatic environments and country-specific issues. Clearly, application of the pT-method is suitable for several experimental designs which are linked to toxicity testing (methods, test species, endpoints). 

Accurate exposure assessments ultimately rely on the accuracy of the methods designed to capture and measure the level of exposure to a contaminant. For example, does a personal monitoring device systematically under- or oversample a contaminant when it is used under field conditions that differ from the laboratory conditions under which it was tested Have validation data been supplied to allow evaluation of such issues ... 

Taguchi, G., Taguchi Methods Design of Experiments. ASI Press. Dearborn. MI, 1993. Veith, A. G., Precision in Polymer Testing An Important World-Wide Issue, Polymer Testing. 7,239 (1987). 

Section 2 discusses the safety implications of the design process and the relevant acceptance criteria required for different safety classes. In Section 3 the design principles for the achievement of the protection objective are recommended and the concept of periodic safety review is discussed in relation to the design issues. Guidance on an appropriate selection of methods for seismic qualification is provided in Section 4, recommendations for qualification by analysis are provided in Section 5, and qualification by test and... 

The decision to test is usually driven by unusual chemistry such as a new catalyst, reaction components, or reaction conditions. Immersion/mass loss method is primarily used in conjunction with microscopic examination. Process fluids from production or pilot runs are primarily used to best simulate potential corrosion. The test methods are custom designed based, in part, on cost and the ability to obtain sufficient quantities of test fluids, and handle the process conditions. Process conditions are tested outside the process control limits (e.g., temperatures, pH) to better accentuate the corrosion potential. These extremes have to be tempered by the stability of the products in the stream. For wall thicknesses greater than 0.250 in. (6.35 mm), a uniform loss of less than 10 mil/year (0.26 mm/year) is considered structurally acceptable. Signiflcandy lower levels of uniform loss are of concern for product or process contamination issues. Microscopic examination is used to determine potential localized corrosion concerns, such as pitting or stress cracking. Indications of pitting or stress corrosion in stamped areas of the coupon are of particular concern. U-bend tests are rarely used because of insufflcient test fluid quantities and availability. 

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