Standardization of 226Ra radionuclide solutions

226Ra reference solutions with radium masses ranging from 0.1 to 5000 ng have found numerous applications in solving a number of metrological problems in the field of environmental control, etc. Methods and equipment are described which are employed to calibrate 226Ra solutions when certifying them as reference standards of the radium mass unit (standard source No. 5427 prepared by O. Honigschmid).