The quantitative determination of C¹⁴ activity /

With the increased use of 014 tagged compounds in biological tracer studies a method for direct and rapid quantitative determination of radioactivity in biological fluids becomes important. One satisfactory but tedious method involves combustion of the organic material in such fluids as blood, plasma, and urine, collection of the CO2 and the precipitation on suitable plates as BaCO3, according to the method described by Yankwich. 1 This method implies that the 014 containing com pound under study be similarly assayed by combustion and counting as BaCO3. A more rapid method involves the direct plating of aliquots of the biological fluids themselves onto suitable counting plates and subsequent determination of radioactivity with a thin mica window (Geiger Mueller) tube. The latter method has been used in some of our studies of the metabolism of nicotinic acid and related compounds. It became apparent, however, that for valid interpretation of the measured activity obtained in this manner, suitable calibration is essential.Work performed at the Los Alamos Scientific Laboratory."Date Declassified: April 1, 1948.""AECD-1845; (LADC-504)."Includes bibliographical references.With the increased use of 014 tagged compounds in biological tracer studies a method for direct and rapid quantitative determination of radioactivity in biological fluids becomes important. One satisfactory but tedious method involves combustion of the organic material in such fluids as blood, plasma, and urine, collection of the CO2 and the precipitation on suitable plates as BaCO3, according to the method described by Yankwich. 1 This method implies that the 014 containing com pound under study be similarly assayed by combustion and counting as BaCO3. A more rapid method involves the direct plating of aliquots of the biological fluids themselves onto suitable counting plates and subsequent determination of radioactivity with a thin mica window (Geiger Mueller) tube. The latter method has been used in some of our studies of the metabolism of nicotinic acid and related compounds. It became apparent, however, that for valid interpretation of the measured activity obtained in this manner, suitable calibration is essential.Mode of access: Internet