Isotope and Impurity CoIntent in Water Triple-Point Cells Manufactured at NMi VSL

The isotopic and impurity coIntent of 15 water triple-point cells, manufactured atNMi VSL in the past three years, were investigated. The isotopic analyses were performed on water specimens sampled at three different stages of the manufacturing process. This allowed us to separate and quantify the influence of the source water and of themanufacturing process (distillation, degassing) on the final isotopic composition of the water in the cells. Inductively coupled plasma mass spectrometry (ICPMS) was conducted on selected water samples to investigate the potential contamination of the source water during the manufacturing process, and to evaluate the impact of impurities on the water triple-point temperature. The temperature differences among the manufactured cells were measured, and correlations between the observed differences and the results of isotope and chemical analysis were studied.