A combustion technique for the assay of tritium, 13C and 14C in a single 10 mg. sample of biological material

Abstract

A rapid method is described for the quantitative combustion of 10 mg, samples of biological materials. Methods for the assay of tritium as tritiobutane and C14 as Cl4O2 on this scale are briefly summarized, and methods of measuring and counting 10 [mu]l.-l0 ml. samples of radioactive gases are descr. Results are presented which demonstrate the quantitative combustion of some standard substances. The closely agreeing results of combusting and assaying in triplicate a sample containing the 3 isotopes are also presented. The various methods of assaying the 3 isotopes are discussed with special reference to C14. It was concluded that (i) gas counting is preferable for tritium especially at low activities and in the presence of Cl4; (ii) the counting of solid samples containing C14 is most reliable if first reduced to a single standard compound (usually BaCO3); (iii) gas counting is simpler than this and more efficient by at least a factor of 10, thus allowing a 10-fold reduction in the dose of isotope used in biological expts.