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Resorcinol-formaldehyde (RF) cryogels were synthesized by the sol-gel polycondensation of resorcinol (R) with formaldehyde (F) and freeze-drying was carried out with t-butanol. Carbon cryogels were obtained by pyrolyzing RF cryogels in an inert atmosphere. Characterization by nitrogen adsorption showed that the carbon cryogels were micro and mesoporous materials with high specific surface areas (S-BET approximate to 550 m(2)/g). Cyclic voltammetry experiments at various scan rates (2 to 200 mV s(-1)) were performed to study the electrical double-layer charging of carbon cryogel electrodes in 0.5 mol dm(-3) HClO4 solution. It has been demonstrated that it is possible to sub-divide the total specific capacitance into the mesoporous and the microporous specific capacitance by analyzing the linear dependence of the charge (q) on the reciprocal of the square root of the potential scan rate (v(-1/2)), and the linear dependence of the reciprocal charge (l/q) on the square root of the potential scan rate (v(-1/2)). The specific capacitance was found to be constant over a wide range of sample weight (12.5 to 50.0 mug) and a very promising specific capacitance value of 150 F/g, was found for this material operating in an acidic 0.5 mol dm(-3) HClO4 solution at room temperature.

A new procedure for the aggregation of human albumin and Tc-99m-labelling of the prepared macroaggregated albumin are presented. Simple methods for quantifying of all the radiochemical impurities existing in Tc-99m-MAA were tested. Thus, 85% methanol was used as the mobile phase in paper and ITL chromatography with Whatman N-o 1 and ITLC-SA strips. A system of two solvents (acetone and 1 M NaCl or 0.9% NaCl) was used for 3 MM paper, ITLC-SA and ITLC-SG strips and silica gel plates as the stationary phase. Low-voltage paper electrophoresis with Whatman 3 MM paper sheets soaked in barbiturate buffer and the gel chromatography column method (Sephadex G-25) were also applied. Filtration through syringe filters, proposed by European and Yugoslav Pharmacopoeia, was performed for comparison. The application of the mentioned tests lead to consistent results for the labelling efficiency ( GT 98.5%) and percent radiochemical impurities of Tc-99m-MAA. Determination of the particles number in a counter chamber and their size distribution under a light microscope with a calibrated ocular scale gave the result of 300000-350000 particles per 1 mg of HA. This confirmed that the human albumin macroaggregates prepared by our new procedure is remarkably improved and convenient for routine diagnostic purposes.