Direct assays, description

In this chapter the validation approach will be explained using a simple and complex example. The simple example is a spreadsheet developed and validated for content uniformity determination by UV assay, while the second one is a routine HPLC potency and related substances determination. The simple example is placed directly into the validation section to further illustrate the validation approach, while the second example is located at the end of the chapter for further reading. Different frames will mark descriptions of these examples. 

The feed to the hydrocracker consists of the heavy naphtha cut from the base crude mix and light cycle oil from the base FCC operation. The hydrocracker simulator requires a description of each of these feeds in terms of the hydrocarbon components shown in Table I. Since these components are not directly measured in the crude assay nor are they predicted by the FCC simulator, special techniques were developed to estimate them from available data. 

Extensive reviews concerning the opportunities for the development of in vitro sensitization methods already exist [41-44], These reviews show that essentially all of the methods address one or other of the key mechanistic steps in the induction of skin sensitization—and these are nicely represented in the OECD adverse outcome pathway description [45], From this large body of work, three methods have emerged whose initial promise has been substantiated by demonstration not only of their predictive merits but also by verification of their robustness in terms of inter-laboratory transferability and within and between laboratory reproducibility [46]. The three methods are the direct peptide reactivity assay (DPRA) [47, 48], KeratinoSens [49, 50], and the human Cell Line Activation Test (h-CLAT) [51-53]. The first of these, the DPRA, addresses the question of chemical reactivity, the second investigates an aspect of keratinocyte activation... 

As for the description of the direct ELISA, the purpose for which the assay is being developed should always be the strongest factor in test reagent optimization. Ultimately, the test will have to be proved to perform on particular samples and under specific conditions, and validation of ELIS As must meet such conditions. 

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