Assessment of chemical form of gaseous 35S species produced during production of H332Po4 and effective reduction of 35S release

The chemical form of gaseous 35S species produced during the production of H332PO4 was characterized in order to reduce 35S release from the radioisotope production laboratory. An air sample was evacuated from the cell in which the H332PO4 production was being carried out, and collected in a sample gas reservoir. Gaseous sulfur species contained in the sample was condensed in a cold trap maintained at -180 degree C and analyzed by gas chromatography using a flame photometric detector. Sulfur dioxide (SO2) was the only sulfur species detected. Equilibrium constant calculations showed that SO2 would be expected to be the predominant species produced by reactions of sulfur molecules (Sn : n = 2 ∼ 8) with oxygen in air. Release of 35SO2 was remarkably reduced by revised production procedures that prevent the reaction between the sulfur vapor and oxygen. (4 figs., 1 tab.)