E Assay

Agut et al. (2011) assessed the different technology transfer options and reported that within Sanofi-Aventis that option 1 (comparative testing) is the approach of choice for critical methodologies, i.e. assay, degradation products, and in some cases water content and dissolution. Option 2 (co-validation) is reserved for less-critical methodologies, i.e. residual solvents by gas chromatography (GC), water content, dissolution and particle size methods whereas, option 4 (transfer waiver) is restricted to pharmacopoeial compendial methods, i.e. appearance, pH, particulate matter, etc. 

E. Assays Based on FTIR Spectroscopy for Assaying Lipases or Esterases... 

Qualification of the erythroid tier 1 assay was more difficult as there are fewer compounds known to induce in vivo erythrotoxicity and the CFU-E assay has not been used to predict in vivo toxicity potential of compounds. Instead, the erythroid tier 1 assay was qualified by comparing IC50 values with the percent peripheral blood reticulocyte reduction using 16 AstraZeneca compounds with similar core chemistry (Figure 17.5). When plotting the results from 15 compounds, = 0.83. 

Amperometric detection in the oxidative mode produced on-column detection limits of 0.07, 4.3, and 0.19 ng for retinol, vitamin D3, and a-tocopherol, respectively (143). A limitation of amperometric detection in vitamin E assays is that it cannot measure a-tocopheryl acetate, owing to the absence of the oxidizable hydroxyl group. 

In spite of these difficulties, this survey produces a lot of arguments which show that protein labeling has been already applied in many diverse fields. It enables us to understand different metabolic events, mechanisms of protein interactions, and allows us to determine with precision many compounds which are present in very low quantities (in nanogram levels or even less). Briefly, the labeling of proteins enables us to follow them in action under in-vivo conditions (turnover, distribution in the body, etc.) and in vitro (i.e. assays of enzymatic activities) or only to facilitate their detection in tissues (e.g. histochemistry) or directly in a live body (scintigraphy). 

Contemporary speciation analysis is developing in two main directions the search for new forms of elements and introduction of the principles of modem chemical metrology into day-to-day practice. Activities encompassed by the former area are qualitative, aimed at the release and identification of often previously undescribed substances involved in living processes that have not been clarified to date. The other area, which requires the introduction of good laboratory practice, comprises routine analyses (i.e., assaying defined element forms) in real-life materials. Although the importance of correct interpretation of quantitative results seems obvious today, it did not always enjoy the status it has today. 

For intracellular enzymes, the picture is compficated because we do not have a clear idea of physiological substrate concentrations and turnover times inside cells indeed, compartmentalization, metabolic channeling, and tight couphng of reactions make it difficult to estimate intracellular concentrations even under ideal conditions (Albe et al., 1990 Srere, 1987). For these reasons, intracellular enzyme assays are typically run at saturating substrate concentrations (i.e., assays) ... 

Minimum of 3 points must be linear (i.e., assay under protein limiting conditions). 

Price RG, Taylor SA, Crutchen E. Assay of laminin fragments in the assessment of renal disease. Kidney Int 1994 47 825-8. 

Robin P, Predine J, Milgrom E. Assay of unbound cortisol in plasma. J Clin Endocrinol Metab 1977 46 277-83. 

Serum Levels. This probably is the most reliable, but it does require very sensi-ti e assay methods for those vitamins required in microgram (10 ) amounts. It also requires knowledge as to how the vitamin is transported free or bound to a plasma protein or cn a specific transport protein. Examples of the latter are transport proteins for vitamin A and vitamin D,. The tocopherols will be found in the lipoproteins (VLDL, LDL, etc.). 

McGonigle, E. Assay validation and inter-laboratory transfer. In Development ami Validation of Analytical Methods (C. M. Riley andT. W. Rosanske, Eds.), pp. 3-13. Elsevier, New York, 1996. 

D2. De Robertis, E., Assay of thyrotropic hormone in human blood. J. Clin. Endocrinol. Metab. 8, 956-966 (1948). 

Forland, S.C. Chaplin, L. Cutler, R.E. Assay of gemfibrozil in plasma by "high-performance" liquid chromatography. Clin.Chem., 1987, 33, 1938... 

Performing chemistry with a very low bias to determine the exact amount of spike Ny would, however, be very difficult and require a large (and hence costly) amount of isotopically enriched material. The solution to this can be another isotope dilution i.e. assaying the spike Y (in solution for example) with accurately assayed material Z of... 

C3. CatteraU, J. B., and Cawston, T. E., Assays of matrix metaUoproteinases (MMPs) and MMP inhibitors Bioassays and immunoassays applicable to cell culture medium, serum, and synovial fluid. Methods Mol. Biol. 225, 353-364 (2003). 

E. Assay of Commercial Aspirin by Sodium Hydroxide Titration... 

Two major applications of DSC techniques for the study of coals, oil shales and oil sands have been identified, namely resource evaluation (i.e., assay and proximate analyses) and specific heat determinations. The information content from DSC is much enhanced when TG is also used. The method of sample containment and choice of experimental variables are critical in the study of these materials. 

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