Gas proportional counting compared with liquid scintillation counting for assaying tritium in biological materials.

Gas proportional counting is a simple and accurate method for determining tritium in biological materials and is suitable for clinical and experimental purposes. Samples of tissue, blood, feces, and urine may be analyzed wthout pretreatment, and the counting procedure is independent of the consistency and composition of the materials. Amounts from 0.001 mg to 75 mg may be counted with equal efficiency (40%). Good agreement was found between results of gas proportional counting and liquid scintillation counting in determining tritium activity in urine. On counting nonhomogeneous biological materials the precision of gas proportional counting is thought to be better than the precision of liquid scintillation counting because radioactivity may be wasted during complicated pretreatment procedures. (auth)