Formation of thiosulfate [35S] by neutron irradiation of potassium chloride and preparation of elementary sulfur [35S].

Potassium chloride was subjected to various kinds of pretreatments and irradiated in a nuclear reactor. Irradiated potassium chloride was dissolved in deaerated aqueous solution of several sulfur-salts. A portion of the solution was chromatographed on a thin layer chromatographic plate and the distribution of 35S-chemical species was determined. Irradiation of potassium chloride degassed at 3x10(-4)Torr resulted in the formation of about 60% of 35S in the form of thiosulfate and remainder was distributed among sulfide, sulfate and elementary sulfur. Thiosulfate[35S] was converted to elementary sulfur[35S] first by reducing to hydrogen sulfide [35S] with nascent hydrogen and then by oxidizing the latter to elementary sulfur[35S] with hexacyanoferrate(III). Elementary sulfur[35S] was finally extracted into benzene. Radiochemically pure elementary sulfur[35S] could be produced by simple procedures with a yield of about 60%. Thiosulfate[35S] was decomposed with acid to elementary sulfur[35S] and sulfur[35S] dioxide. The former was separated by centrifuging and dispersed in boiling water to form colloidal suspension of elementary sulfur[35S]. Approximately 40% of 35S was recovered as colloid.