The assay of tritium-labelled folate in faeces by the oxygen flask combustion technique followed by liquid scintillation counting.

The assay of tritium-labelled substances in faeces requires conversion of tritium into either tritium gas (Payne and Done, 1958) or tritium-labelled water. Belcher (1961) and Kremenchuzky, Musso, Hoffbrand, and Viola (1967) used wet oxidation of faeces followed by liquid scintillation counting, while Burns and Glass (1963) used dry oxidation in a bomb calorimeter. There is a need for a reproducible and relatively sensitive means of measuring tritium activity in tissues and materials such as faeces. This method was developed in order to measure intestinal absorption of tritium-labelled compounds such as folic acid and its analogues and is a modification of the oxygen-flask combustion technique developed by Schoniger (1955). L