Validation of certification protocols for oxidised mercury gas generators used in the field
The aim of this work package is to validate a certification protocol for the certification of oxidised mercury (HgII) gas generators used in the field for mercury concentrations present in the atmosphere at low ng/m3 levels and higher concentrations typical for emission sources. As a result, the protocol will be applicable to different types of gas generators e.g. liquid based, dry based gas generators and Hg0 to HgII converter systems and as part of the validation, the repeatability, reproducibility, bias and uncertainty of the gas generators will be evaluated.
The specific aims of each Task are:
Task 2.1. The aim of this task is to evaluate state-of-the-art dual analytical systems (analysers) used for the quantitative determination of Hg0 and HgII.
Task 2.2. The aim of this task is to evaluate state-of-the-art HgII gas generators.
Task 2.3. The aim of this task is to adjust the certification protocol to determine the output of liquid evaporative HgCl2 gas generators developed within the EMPIR 16ENV01 MercOx project, to obtain a protocol which is fit-for-purpose for a wider range of HgII gas generators used in the field.
Task 2.4. The aim of this task is to validate the traceable certification protocol for oxidised mercury gas generators developed in A2.3.1 for mercury concentrations present in the atmosphere at low ng/m3 levels and higher concentrations from emission sources. As part of the validation, the repeatability, reproducibility, bias and uncertainty of the gas generators will be evaluated.
The aim of this task is to evaluate state-of-the-art dual analytical systems (analysers) used for the quantitative determination of Hg0 and HgII. This information will be used to determine the HgII concentration in air and to achieve accurate determinations by atomic spectrometry detectors.
| Activity number | Activity description | Partners (Lead in bold) |
| A2.1.1 M03 | Lumex, with input from PSA, LGC and VTT, will compile a list of performance characteristics (e.g. repeatability, reproducibility, accuracy, linearity, drift, bias and robustness) and uncertainty sources of state-of-the-art dual analytical systems (e.g. thermal converter efficiency and undesirable species interconversion). | Lumex, PSA, LGC, VTT |
| A2.1.2 M12 | LGC and VTT with support from Lumex, PSA and JSI will assess the performance characteristics in A2.1.1 of state-of-the-art dual analytical systems. LGC will develop methods and determine the thermal converter efficiency of state‑of‑the-art dual analytical systems by using HgII gas generators, supplied by PSA, VTT and Optoseven, and atomic spectrometry detectors, supplied by PSA and Lumex, [Atomic Fluorescence Spectrometry (AFS) and Atomic Absorption Spectroscopy (AAS)]. The used methods are based on ICP-MS/MS with species specific Isotope Dilution Mass Spectrometry calibration. Two independent setups will be used based on either direct coupling ICP-MS/MS to a HgII and Hg0 gas generator, or indirect ICP‑MS/MS analysis by use of sorbent traps. As an alternative method, JSI will use the 197Hg radioactive tracer (from EMPIR project 16ENV01 MercOx) to determine the converter efficiency at very low mercury concentrations in the pg to ng/m3 range. Extremely high specific activity of the tracer enables, testing of specific conversion of mercury during calibration, transport, and preconcentrating steps at pg/m3 concentrations that are relevant for atmospheric mercury speciation measurements. The adverse sorption effects of HgII gases on the dual analytical systems’ components (such as reversible adsorption, absorption and chemisorption) will be investigated in relation to carry-over, memory effects. | LGC, Lumex, PSA, VTT, JSI |
| A2.1.3 M14 | To optimise the dual analytical systems thermal converter efficiency, CNR, with support from LGC, Lumex, PSA, JSI and VTT, will use univariate and multivariate statistically significant approaches. The multivariate optimisation will be performed using the chemometric technique Design of Experiment (DoE). | CNR, LGC, Lumex, PSA, JSI, VTT |
| A2.1.4 M16 | Based on results from A2.1.1 – A2.1.3, Lumex and PSA, with support from LGC, JSI and VTT, will improve the accuracy of the dual analytical systems. LGC and VTT, with support from PSA and Lumex, will determine the repeatability, reproducibility and uncertainty of these dual analytical systems including the repeatability, reproducibility and uncertainty of the thermal converter using methods developed in A2.1.2. | LGC, PSA, Lumex, JSI, VTT |
The aim of this task is to evaluate state-of-the-art HgII gas generators. In this task the HgII gas composition will be examined and the presence of reduced mercury species, i.e. Hg0, investigated. The project will estimate the salts purity, the derived solutions species purity (i.e. percentage of HgII in solution and presence of other species) as well as the solutions stability and the exact mercury concentration in the liquid mixture with the associated uncertainty.
| Activity number | Activity description | Partners (Lead in bold) |
| A2.2.1 M03 | PSA, with input from LGC, VTT and JSI, will compile a list of significant performance characteristics (e.g. repeatability, reproducibility, accuracy, linearity, drift, bias and robustness) and uncertainty sources (e.g. generator selectivity, HgII transportation efficiency, composition HgII solution) of commercially available and newly developed HgII gas generators. The gas generators to be investigate will include one liquid evaporation (VTT and Optoseven), one dry based gas generators (PSA) and one instrument based on Hg0 oxidation (JSI). | PSA, LGC, VTT, JSI |
| A2.2.2 M05 | Using the significant performance characteristics and the uncertainties sources compiled in A2.2.1, LGC, in collaboration with PSA and VTT will set up an uncertainty calculation for the three different types of HgII gas generators detailed in A2.2.1. | LGC, PSA, VTT |
| A2.2.3 M18 | VTT and LGC, with support from PSA and JSI, will evaluate the performance characteristics of the three HgII gas generator systems, from A2.2.1 and A2.2.2, focusing on the significant performance characteristics as compiled in A2.2.1. The evaluation will be done using Isotopes of Mercury that are available at JSI. LGC and JSI, with support from PSA and VTT, will evaluate the HgII gas transfer efficiency of the gas generators, including the effect of HgII reversible adsorption, irreversible (or very slow reversible) absorption and chemisorption/reduction. | VTT, LGC, PSA, JSI |
| A2.2.4 M24 | LGC, with support from VTT, TÜV Rheinland and Lumex, will determine the elemental purity of HgII solutions and salts used in the HgII gas generators detailed in A2.2.1 LGC, with support from VTT, TÜV Rheinland and Lumex, will develop a method for chromatographic purity determination of HgII and will apply this method to the HgII stock and working solutions (e.g. HgCl2 at ng/g and µg/g levels) and salts (e.g. commercially available pure HgCl2 salt used with dry HgII generators), used for HgII gas generators. Using the obtained methods, mercury total mass fraction analysis of the salts used in one dry based HgII gas generator will be performed. Additionally, LGC, VTT, TÜV Rheinland and LUMEX will monitor the HgII solution stability over a period of 6 months with sampling frequency of at least 1 per month. The monitoring will include the effect of the different storage conditions (e.g. temperature, light, etc.) on the mass fraction of mercury and species distribution. Based on the results obtained the uncertainty of the HgII concentration in the liquid solutions will be determined. | LGC, VTT, TÜV Rheinland, Lumex |
| A2.2.5 M26 | LGC with support from Lumex, TÜV Rheinland and VTT will document the conclusions of A2.2.4 in the form of a good practice guide regarding storage and HgII solutions stability. | LGC, Lumex, TÜV Rheinland, VTT |
The aim of this task is to adjust the certification protocol to determine the output of liquid evaporative HgCl2 gas generators developed within the EMPIR 16ENV01 MercOx project, to obtain a protocol which is fit‑for‑purpose for a wider range of HgII gas generators used in the field. This task output is a traceable certification protocol that can directly be turned into a new documentary standard under development by European standardisation bodies, e.g. CEN/TC264/WG8, to ensure metrological soundness, traceability and comparability of measurement results across Europe.
| Activity number | Activity description | Partners (Lead in bold) |
| A2.3.1 M20 | Using input from A2.1.4, A2.2.1, A2.2.2 and A2.2.3, VTT, in collaboration with TÜV Rheinland, PSA and Lumex will adjust the certification protocol developed within the EMPIR 16ENV01 MercOx project which determines the output of liquid evaporative HgCl2 gas generators. The protocol will be adjusted to obtain a protocol that is applicable to different types of gas generators, commonly used in the field e.g. liquid based, dry based gas generators and Hg0 to HgII converter systems. | VTT, TÜV Rheinland, PSA, Lumex |
| A2.3.2 M35 | Based on the results of A2.1.4, A2.2.5, A2.4.4 and A3.2.5, VTT, in collaboration with TÜV Rheinland, PSA and Lumex will finalise the certification protocol developed in A2.3.1 by including relevant validation data such as repeatability, reproducibility, bias and uncertainty evaluation. | VTT, TÜV Rheinland, PSA, Lumex |
| A2.3.3 M36 | VTT, with support of PSA, Lumex, TÜV Rheinland, JSI, VSL, CNR and LGC will review the certification protocol from A2.3.2. VTT will send the final document to the coordinator. The coordinator will then submit it to EURAMET as D3 “Protocol for the SI-traceable certification of oxidised mercury (HgII) gas generators used in the field.“. | VTT, PSA, Lumex, TÜV Rheinland, JSI, VSL, CNR, LGC |
The aim of this task is to validate the traceable certification protocol for oxidised mercury gas generators used in the field and developed in A2.3.1 for mercury concentrations present in the atmosphere at low ng/m3 levels and higher concentrations from emission sources. Validation of the protocol will be achieved using different types of gas generators, as part of the validation, the repeatability, reproducibility, bias and uncertainty of the gas generators will be evaluated.
| Activity number | Activity description | Partners (Lead in bold) |
| A2.4.1 M22 | Based on the outputs from A2.3.1 VTT, in collaboration with LGC, VSL, Lumex, JSI and PSA will provide experimental approaches to validate at least three different types of HgII gas generators e.g. liquid based and dry based gas generators and Hg0 to HgII converter systems. Thereby taking into consideration existing standards such as ISO 10723, EN 14211, ISO 12963, ISO 6143 and ISO 15796 and the US EPA and NIST interim protocols for establishing traceability of Hg0 evaporative gas generators and HgII evaporative gas generators. The metrological requirements (e.g. SI-traceability and uncertainty) will also be defined by VTT and VSL and in consultation with the project SC (A4.1.1). | VTT, LGC, VSL, Lumex, JSI, PSA |
| A2.4.2 M24 | VTT, PSA and JSI, with support from VSL, Lumex and TÜV Rheinland, will certify at least three different HgII gas generators (HgII gas generator, dry based HgII gas generator and Hg0 converter HgII gas generator) according to the protocol developed in A2.3.1. The protocol will be validated for the full range for mercury emissions and low concentrations in the atmosphere in the low ng/m3 range. | VTT, VSL, Lumex, JSI, PSA, TÜV Rheinland |
| A2.4.3 M25 | From the data obtained in A2.4.2, VTT and JSI with support from PSA, Lumex, VSL and TÜV Rheinland will perform a repeatability, reproducibility, bias and uncertainty evaluation for the gas generators, which include HgII gas generator, dry based HgII gas generator and Hg0 converter HgII gas generator. | VTT, JSI, PSA, Lumex, VSL, TÜV Rheinland |
| A2.4.4 M27 | Using the results from A2.4.1 – A2.4.3, a report will be compiled by VTT and JSI, in collaboration with LGC, Lumex, PSA, TÜV Rheinland and VSL, describing the validation of the protocol and how it is to be used in practice as a validation report and guidance document. VTT will send the final protocol to the coordinator. The coordinator will submit it to EURAMET as D4 “Validation report for the certification of oxidised mercury gas generators including (1) metrological evaluation of state‑of‑the‑art dual Hg0 and HgII analytical systems, (2) repeatability, reproducibility and uncertainty evaluation of the certification procedures at representative concentration levels extended to the low ng/m3 level.. | VTT, JSI, LGC, Lumex, PSA, TÜV Rheinland, VSL |