Primary mercury gas standards, traceable to the SI, have been developed which can be used to underpin a NIST traceability framework for the calibration of vapor phase continuous emission monitoring systems (CEMS). A gas standard, which is based on a commercial gas generator, has been certified for gaseous elemental mercury output at specified generator output set points. The standard, termed the NIST Prime (NP) was certified at selected set points in the range 0.25 μg/m³ to 38 μg/m³ by isotope dilution inductively coupled plasma – mass spectrometry (ID-ICP-MS) using two alternative approaches, based on directly coupled gas sampling, and activated carbon sorbent trapping. Both approaches have been used to provide NIST traceability for electric utility mercury CEMS. The directly coupled method yielded expanded measurement uncertainties ranging from approximately 5.5% relative at 0.5 μg/m³, to approximately 1% relative at 38 μg/m³, and an estimated limit of quantitation (LOQ) of 0.06 μg/m³. The sorbent trapping method in contrast, yielded expanded uncertainties of approximately 1% relative at all sampling points, with an LOQ of 0.001 μg/m³.

已开发出可溯源至SI的主要汞气标准，可用于支持NIST溯源框架，以校准气相连续排放监测系统（CEMS）。基于商用气体发生器的气体标准已通过认证，可在指定的发生器输出设定点输出气态元素汞。在0.25μg/ m ³至38μg/ m ³范围内的选定设定点上，通过NIST Prime（NP）认证的标准同位素稀释电感耦合等离子体质谱法（ID-ICP-MS）使用两种替代方法，基于直接耦合气体采样和活性炭吸附剂捕集。两种方法都已用于为公用事业汞CEMS提供NIST可追溯性。的直接耦合方法产生在0.5微克/米扩展测量的不确定性范围从相对约5.5％³在38微克/米，相对于约1％³，和定量的估计限制为0.06微克/米（LOQ）³。相反，吸附剂捕集方法在所有采样点产生的相对不确定度约为1％，LOQ为0.001μg/ m ³。