| Popis: |
Formaldehyde is an important hazardous air pollutant, classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC). It is emitted directly by many anthropogenic and natural sources, and formed as a secondary product from volatile organic compounds (VOCs) photo-oxidation. Formaldehyde is, as well, a significant source of radicals in the atmosphere resulting in ozone and secondary organic aerosols formation. Routine measurements of formaldehyde in regulatory networks within Europe (EMEP) and USA (EPA Compendium Method TO 11A) rely on sampling with DNPH (2,4-Dinitrophenylhydrazine)- impregnated silica cartridges, followed by analysis with HPLC (High-performance liquid chromatography). In the framework of the EURAMET-EMPIR project « MetClimVOC » (Metrology for climate relevant volatile organic compounds: http://www.metclimvoc.eu/), the European ACTRIS (Aerosol, Cloud and Trace Gases Research InfraStructure: https://www.actris.eu/) Topical Centre for Reactive Trace Gases in-situ Measurements (CiGas), IMT Nord Europe unit – France, organized a side-by-side intercomparison campaign in Douai-France, dedicated to formaldehyde measurement in a low amount fraction range of 2 - 20 nmol/mol, from 30 May to 8 June 2022. The objectives of the intercomparison are to evaluate the instruments metrological performance under the same challenging conditions, and to build best practices and instrumental knowledge. Here, we present the results from the intercomparison, where ten instruments belonging to seven different techniques were challenged with the same formaldehyde gas mixture generated either from a cylinder or from a permeation system, in different conditions (amount fractions, relative humidity, interference, blanks, etc.), flowing through a high-flow (up to 50 L/min) Silcosteel-coated manifold. The advantages/drawbacks of the techniques will be discussed. |
