The analysis of water vapor impurity is important in a number of cutting-edge technology, fields such as the semiconductor manufacturing process, display industry, and gas industry. The sensing of trace-moisture in gases, with an amount-of substance fraction less than 1 μmol.mol-1, has become increasingly important in the recent decade, because it has been recognized that even such a small amount of water vapor plays a critical role in the yield and product quality. International Vocabulary of Metrology (VIM) defined Metrological Traceability that is a property of a measurement result whereby the result can be related to a reference through a documented unbroken chain.