| Abstract Title: | Validation of elemental and oxidised Hg gas generators by SI traceable ICP-IDMS measurements |
| Presenter Name: | Panayot Petrov |
| Company/Institution: | LGC ltd. |
| Session: | Special Session - Metrological Traceability for mercury analysis and speciation |
| Day and Session: | Wednesday 27th July - Session Three |
| Start Time: | 14:00 UTC |
| Co-Authors: | Panayot Petrov,Warren T. Corns |
Abstract Information :
Mercury gas generators are used to calibrate mercury analysers at testing laboratories and in the field. Currently, there is lack of traceability for measurements using generators in the field. Such generators can be validated against calibration methods specified in ISO and ASTM standards and, for emissions monitoring in the USA, to a NIST interim-protocol. Primary methods are, however, not available to provide full SI traceability with adequately low measurement uncertainty. The aim of this study was to develop a metrologically SI traceable method, based on gas phase ICP-IDMS, which can be applied to the certification of mercury gas generators and, therefore, improve the measurement comparability and decrease the uncertainty of the results from mercury field measurements. To achieve this, a novel online calibration approach for the direct quantification of gaseous Hg by ICP-IDMS was developed. The proposed methodology was found suitable for validating the Hg fraction in span gases with concentrations between 10 ng m-3 and 10 æg m-3. The input parameters which affect the generators? output and ICP-MS detector input were critically evaluated and the combined measurement uncertainty was estimated by using the bottom-up approach. By providing calibration with direct traceability to SI units for the mass fraction of Hg in span gases with relatively low measurement uncertainty (< 10%, k=2), the developed method will support standardisation activities of the European Committee for Standardization (CEN).
