Method of determining substances soluble in H2O or other liquids, e.g., Ba, by concentration thermoradiometry

The method uses the principle of proportionality between concentration and the overall amount of liberated reaction heat of the material to be determined with a reagent, eg., sulfuric acid. In lieu of temperature measurement, 85Kr is previously dissolved in the reagent. The radionuclide solubility decreases with temperature. The radioactivity of liberated 85Kr gas or the reduction in activity of the system to be analyzed is measured. In the analysis, side reactions must be prevented which would cause temperature changes of the solution independent of the material to be determined. Reactions of various types may be employed, such as complex formation, precipitation, redox reactions, polymerization, condensation, hydratation, etc. A calibration curve is used for determining the sought material concentration. (M.K.)