Biological Testing

Abstract: Before trace amounts of organic constituents that are in aqueous solutions as complex mixtures can be analyzed, the solutions must be concentrated. This is necessary so that a sufficient mass of organics can be obtained for separation and subsequent identitisation. An analogous situation exists for determining the biological activity of such unknown or mostly unknown trace organic constituents in waters of environmental or public health concern. This is especially true for biological testing of long duration or testing that requires many large test species. For instance, a long-term feeding study of mice could require organic material from many thousands of liters of water. Procedures which combine several techniques have been developed to achieve the highest possible recovery of organics. Nevertheless, there are still critical areas, including changes in organic residues that can occur between preparation of the concentrates and biological testing or chemical analysis. The choice of method or combination of methods for concentration is dependent on such factors as the volatility of the organic constituent to be tested, the degree of concentration required, and the biological test system to be used. Kopfler (l980a) divides concentration methods into two basic categories: I . concentration-those processes in which water is removed and the dissolved substances are left behind. Examples are freeze concentration, lyophilization (freeze drying), vacuum distillation, and membrane processes such as reverse osmosis and ultrafiltration. A common disadvantage to

Abstract: Processes for testing immobilized biological material with generally biochemical and histochemical methods, particularly enzyme, immuno and hormone chemical methods can be improved by adhering the biological material to the surface of a support and then fixing the support to a plate. The plate is constructed in such a way that the biological material is protected from damage. Using a biological testing technique such as thin section immunofluorescence testing the invention makes it possible to carry out biochemical tests in a more rational and trouble-free manner than with hitherto known methods. If necessary, a random number of tests can be performed side-by-side on a single plate. The invention makes it possible to simply and rapidly prepare frozen section products and store them in a space-saving manner at very low temperatures. The adhesion of the frozen sections to the support can be improved by coupling chemicals which react with the tissue by bonding thereto to the support.