The samples are synthetic, and made from pure water, salts and pure standard chemicals. Most assigned concentrations are calculated
from the gravimetric data of the preparation. The estimation of the laboratories' performance is based
on the recoveries of these assigned concentrations and is, therefore, independent of the number of
participants per round.
Assigned concentrations of the parameters are chosen with respect to the concentrations observed in
natural ground and surface waters. It is always aimed to copy the relevant inorganic matrix as close
to natural water samples as possible. Therefore, our proficiency testing items are not simple standard solutions,
but are prepared in such a way that they practically do not differ from real water samples.
They can be analysed exactly like real samples in routine analysis. No further preparation steps are
necessary. Two proficiency testing items at different concentration levels are distributed to the laboratories
in each proficiency testing round.
Based on extensive quality assurance measures during the sample production,
we can ensure high accuracy of the assigned concentrations. In each round the correctness
of the assigned values, homogeneity and stability of the PT items are checked.
The proficiency testing items of the Environment Agency Austria are ground-, surface-, drinking- or wastewater samples, partly fortified.
Details: UBA and Annual Programme 2026