Establishment of SI Traceability and Certification of CRMs/BNDs of Aqueous Elemental Solutions Produced In-house and Through RMP Under Metrology in Chemistry Programme at NPL, India

CSIR-NPL, NMI of India, plays the vital role in the field of Metrology in Chemistry (MiC) programme related to inorganic materials, for which the SI traceability is established linking through the National Standards of Mass (kg). The present paper is based on the development of BNDs of aqueous elemental standard solutions for their dissemination to the testing/calibration laboratories. The mass fraction of the certified value of the BNDs ranging from 1 to 10,000 mg/kg is determined gravimetrically, and the SI traceability is established for the pure substance used as the starting materials of BNDs. The associated combined uncertainty has been estimated considering the uncertainty sources due to homogeneity, long-term stability and gravimetric preparation including air buoyancy corrections. In all the BNDs, the associated uncertainty is found to be less than 1% and the major uncertainty contribution has been shown due to the long-term stability source.