The primary function of a quality control (QC) laboratory is to ensure that only acceptable product leaves the production facility. To this end, the gas within each container is analysed for a specified list of trace impurities.
Some of the most commonly specified molecules in pure gas products are nitrogen, oxygen, carbon dioxide (CO2), carbon monoxide, total hydrocarbons, and moisture. While some gaseous impurities can be easily quantified with traditional analytical technologies, some demand more advanced solutions.
This is particularly true for moisture. Its analysis is fraught with difficulty due to water’s relatively low vapour pressure, high affinity for surfaces, and temperature-dependent behaviour. To alleviate these challenges, moisture measurement is almost always performed using an instrument specifically designed for the purpose. Historically, these instruments have been based on principles involving interactions with solid surfaces; once equilibration is achieved, a characteristic aspect of the moisture-surface interaction is measured. Not surprisingly, the time involved with these techniques frequently causes moisture analysis to represent the ‘bottleneck’ in pure gas product QC.
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