Fifth EC-JRC aromatic compounds interlaboratory comparison with automatic analysers.

This report presents the results of the fifth inter-laboratory comparison for BTEX automatic analysers performed at the JRC Ispra from the 23rd to the 26th of September 2019. Thirteen national reference laboratories and fifteen instruments participated in this exercise. Six concentration levels were tested during the inter-laboratory comparison. Benzene concentrations ranged from 1 to 20 μg/m3. The exercise was evaluated according to ISO 13528 methodologies for the evaluation of inter-laboratory proficiency assessment and the recommendation of the protocol N37 of the AQUILA network. Participating laboratories were identified as requested by the afore-mentioned protocol. The robust average value calculated according to ISO13528 was adopted as reference value for the exercise. The report provides information on the technique and instrumentation used by each participant and shows the results of linearity tests, identification of outliers, repeatability, reproducibility, and robustness of the method. Furthermore, parameters to evaluate individual laboratory results: repeatability score, Z-score, bias and En scores are also provided. In general, the results showed in terms of accuracy and precision a behaviour similar to the previous inter-laboratory exercise (EUR-28692-EN). The decrease in concentration avoided problems of sample’s overload at the highest concentrations, i.e. toluene. For benzene and toluene, average repeatability and reproducibility values were about 6 % and 13 %, respectively. Ethyl-benzene, m,p-xylene and o-xylene showed higher repeatability values of around 9 %, while their values of reproducibility were about 20 %.