New Japanese certified reference materials for electrolytic conductivity measurements

The National Metrology Institute of Japan (NMIJ) has established three certified reference materials (CRMs) in electrolytic conductivity with a primary Jones-type cell: aqueous solutions of potassium chloride with different molalities (1 mol kg−1, 0.1 mol kg−1 and 0.01 mol kg−1) all supplied in glass bottles. The uncertainties were estimated from standard uncertainties of measurements (impedance, temperature and integrity of cell geometry), measurement’s repeatability, homogeneity of a batch and the storage stability of solutions. The storage stability of candidate NMIJ CRMs of upper and lower concentrations was examined with a secondary cell.