An improved technique for assay of C14O2 in expired air using the liquid scintillation counter.

Abstract

Abstract A rapid and efficient system is described which facilitates the analysis of C 14 O 2 in large samples of expired air. The method employs a modification of the method of Passmann, Radin, and Cooper, 2 using methylbenzethonium chloride (Hyamine-10-X) for solubilization of carbonate in toluene. The initial step involving trapping in aqueous base has been eliminated. Radioactivity is measured in a liquid scintillation spectrometer. The total C 14 O 2 radioactivity and specific activity in air from a human expiring less than 1 × 10 −6 mc. per minute may be accurately measured with a minimum of time and manipulation. The direct trapping and analysis of carbon dioxide expired by small animals is also described.