European inter-laboratory comparison exercise for the analysis of PAHs on PM10 quartz filters

Eighteen European reference laboratories of air quality had been involved in a comparison of PAH analysis on particulate matter (PM) based on the use of field quartz filter samples. Four PM10 samples and two blanks were selected for the comparison with the purpose of covering a representative range of concentrations of a typical 24 hours low volume sampling. Laboratory results were treated according to ISO 5725 from which repeatability and reproducibility values for the comparison were calculated. In general, inter-compound median repeatability and reproducibility values ranged along the samples from 2.1 to 7.4 % and 23.6 to 61 %, respectively. The median overall expanded uncertainties (OEU) was 30 % for the highest concentration filter reaching 50 % for the lowest concentration filters. OEU was higher for the lighter compounds (Phenanthrene and Anthracene), characterised by a higher blank level, and for compounds like Chrysene or Dibeno[a,h]Anthracene, which showed difficult analytical resolution. Median OEU were in agreement with typical analytical expanded uncertainties estimated by the participants and in line with the data quality objectives of the European Directive 2004/107/EC No significant differences were noted when comparing the different analytical techniques from the exercise’s results. Nevertheless, other factors such as the use of certified reference materials and the laboratory blank were the reason of important biases. Moreover, the chromatographic separation of some isomers was identified as critical by all the laboratories suggesting the use of specific columns and the introduction of a quality assurance procedure to control of the separation efficiency previous analysis.JRC.H.2-Air and Climat