Development of a certified reference material for composition of high-purity copper as a transfer standard within GET 176-2013

Abstract

Introduction. The paper gives information on the development of a certified reference material (CRM) for composition of high-purity copper (Cu CRM UNIIM). The CRM is included as the transfer standard into the State primary standard of the mass (molar) fraction and mass (molar) concentration of the component in liquid and solid substances and materials based on coulometry GET 176-2013. Materials and methods. The CRM represents pieces of oxygen-free copper wire rod, brand KMB, produced according to GOST R 53803-2010, weighing from 0.5 to 1g. The CRM is packed in plastic vials with the capacity of 30 or 50 cm 3 . The certified characteristic of the CRM is copper mass fraction in copper wire rod, expressed in percentages. The certified value for copper mass fraction was established by the primary method of controlled-potential coulometry using the State primary standard GET 176-2013. Results . The permitted interval of the certified value for copper mass fraction in the CRM is from 99,950 % to 100,000 %. The relative expanded uncertainty (k=2) of the certified value for copper mass fraction does not exceed 0,030 %; the relative standard uncertainty due to inhomogeneity does not exceed 0.010 %; the relative standard uncertainty due to instability does not exceed 0.010 %. The shelf life of the developed CRM is 10 years provided that standard storage conditions are ensured. Discussion and conclusions. The developed CRM is included into the State register of type approved RMs under the number GSO 10800-2016. The CRM of high-purity copper (Cu CRM UNIIM) as a transfer standard is intended for reproduction, storage and transfer of the copper mass fraction unit to other reference materials and chemical reagents by the method of comparison using a comparator and by conducting direct measurements. This CRM may also be used: – for verification of measuring instruments (MIs) according to the state verification schedule described in GOST R 8.735.0-2014, – for calibration, graduation of MIs; control of metrological characteristics when conducting MI tests, including for the purposes of type approval; – for validation of measurement procedures, accuracy control of measurement procedures in the process of their implementation.