New Primary Standards for Establishing SI Traceability for Moisture Measurements in Solid Materials

A European research project METefnet addresses a fundamental obstacle to improving energy-intensive drying process control: due to ambiguous reference analysis methods and insufficient methods for estimating uncertainty in moisture measurements, the achievable accuracy in the past was limited and measurement uncertainties were largely unknown. This paper reports the developments in METefnet that provide a sound basis for the SI traceability: four new primary standards for realizing the water mass fraction were set up, analyzed and compared to each other. The operation of these standards is based on combining sample weighing with different water vapor detection techniques: cold trap, chilled mirror, electrolytic and coulometric Karl Fischer titration. The results show that an equivalence of 0.2 % has been achieved between the water mass fraction realizations and that the developed methods are applicable to a wide range of materials.