Short- and long-term stability of electrolytic conductivity certified reference materials

Electrolytic conductivity is a common parameter measured within industry. Proper usage of electrolytic conductivity sensors requires the periodic calibration using solutions of known conductivity. This parameter can be disseminated through the use of certified reference materials (CRMs) produced according to ISO 17034. A part of the certification of reference materials relates to their stability both in the material they are packaged in and as a function of time, both at the short- and long-time scales. Electrolytic conductivity CRMs produced at DFM A/S are evaluated for the stability in various bottle types, and under various storage and transport conditions. Materials with nominal conductivity values between 10 mS m(-1) and 10 mS m(-1) are shown to be stable at short-time (similar to 1 month) and long-time (expected shelf life and beyond) scales.