Standardization of natural tritium measurements

A series of water samples prepared in Stockholm from tritium-free water and NBS-standard tritiated water have been used to check the accuracy of natural tritium measurements in our three laboratories. There is evidence of pick-up during analysis to the extent of 1-2 TU in one of the laboratories, but otherwise all results from the three laboratories agreed well with the values calculated from preparation of the samples. Agreement waa also obtained on a second series of reference samples prepared and distributed by the International Atomic Energy Agency, Vienna.