45959 2018 eng 746 753 12 85 article De Gruyter Oldenbourg 1 -- -- -- Especially trace amounts of water vapour in gases can be reliably determined by coulometric trace humidity sensors. The principle of these sensors is based on water vapour absorption in a hygroscopic layer and its subsequent electrolytic decomposition. The calibration of sensors was performed in the humidity range, expressed as frost point temperature, from −30°C to −80°C . This range is equivalent to volume fractions smaller than 376 µL·L−1. Generated humidity was measured with coulometric sensors and a chilled dew point hygrometer that was used as reference. An empirical non-linear function was found between sensor signal and measured reference humidity. This function consists of two parameters with a measurement uncertainty. Both calibration parameters were checked by means of one-way analysis of variance. It showed that gas specific function can be used for humidity measurement in nitrogen, hydrogen, dinitrogen monoxide, compressed and synthetic air. It is possible to determine trace humidity in all tested gases with an expanded uncertainty less than 2.1 K (coverage factor k=2 ) regarding frost point temperature. tm - Technisches Messen 10.1515/teme-2018-0031 0171-8096 13.12.2018 Carlo Tiebe Marc Detjens Ulrich Banach Thomas Hübert eng uncontrolled Trace humidity eng uncontrolled Coulometric sensor eng uncontrolled Measurement uncertainty eng uncontrolled ANOVA Analytische Chemie Verlagsliteratur Datei im Netzwerk der BAM verfügbar ("Closed Access")