Tritium and(14)C counting in tissue samples by using liquid scintillation method.

The combustion method has been modified to increase the recovery of tritiated water after combustion of a tritium-labeled tissue sample. This was accomplished by cooling the bottom of the combustion flask in a dry ice-acetone bath while irradiating the top with an infrared lamp. The procedure resulted in at least 92% to 102% recovery of the tritiated water. The NCS solubilizer was found to be superior to hyamine for solubilizing(14)C labeled tissue samples. The samples yielded light yellow-colored solutions when incubated for 15 hr at 50-55C. The counting efficiency of this solution was 75% or higher.