Development of standard reference materials for radioassay

The standardization of a measurement system is crucial. Most measurement systems rely on direct comparisons between a standard and the unknown sample. Therefore, it is important for the standard to be as similar as possible to the sample. The reliability and limitations of an SRM in its application to the intended measurement system, along with any precautions that should be observed in its use, are explicitly stated on the certificate that accompanies each SRM. Obvious information appearing on the certificate would include intended use, specific radionuclide composition or the properties certified, methods used, the size of samples that should be used to insure homogeneity, etc. Not so obvious, but highly important, is the inclusion of information about precautions that should be observed in the use of an SRM to achieve accurate measurements. Standard Reference Materials for radioassay are essential in today's measurement process. Many SRM's are routinely used in the quality assurance programs of well known laboratories. The authors' opinion, NBS (National Bureau of Standards) will continue to support this category of SRM's as long as the measurement need exists