All liquid radionuclide standards are prepared gravimetrically from NIST traceable solutions. After preparation all standards are QC tested with our calibrated counting systems.

Analytics will provide relative expanded uncertainties (expressed in % of value) or expanded uncertainties (expressed in same units as the certified value) with a coverage factor of 2, which approximates a 95% confidence level for all standards. Uncertainties are estimated using the guidance in NIST Technical Note 1297, "Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results".