Accurate Determination of Tritium in Biosystems

The accurate determination of tritium specific activities in tissue water as well as in organic components of biosystems is de-scribed. The isotope effect arising intrinsically in the separation of tissue water from biological samples is found as a critical error source even in a fully optimalized method for the biotritium measurement. The tritium fractionation caused in the process of tissue water separation is precisely quantified by the investigation of two different simulated systems: HTO/H₂0 and alkali metalchloride solutions in HT0/H₂0. The results are applied to the study of a real biological system and possibilities of error correction are discussed.