Description of the IFA Test Systems PT-Scheme


In Austria, the quality of ground and surface water is monitored since the early 90´s. About 2000 groundwater and 200 river water sites are sampled regularly and analysed for numerous inorganic and organic parameters in a nationwide measurement network. The exact range and frequency of the water analyses are legally regulated. This permanent and comprehensive measurement programme requires reliable and accurate results of analysis.

In 1995, the Center for Analytical Chemistry at the IFA-Tulln started to build up a PT scheme for external quality assurance in water analysis on behalf of the Federal Ministry of Sustainability and Tourism. Since then, this scheme has been extended to a multiplicity of inorganic and organic parameters. It is an important part of the nation-wide measurement programme.

The PT scheme is open to all laboratories that are interested in testing their analytical performance. More than 800 laboratories from 30 countries participated in our interlaboratory comparisons.

Successful participation in the scheme is recognised by the Federal Ministry for Digital, Business and Enterprise, which holds the accreditation body for testing laboratories in Austria.

The IFA-Tulln is located close to the Danube river approximately 40 kilometres northwest of Vienna and was opened in 1994. It is a department of the University of Natural Resources and Life Sciences, Vienna and is called "Department of Agrobiotechnology, IFA-Tulln".

Our institute, the Center for Analytical Chemistry has 800 m2 laboratory space, a friendly working atmosphere and modern instrumentation for environmental trace analysis.


The PT samples are prepared at the IFA-Tulln. They usually consist of synthetic ground or surface water, which is made from pure water, salts and pure standard chemicals. Most target concentrations are calculated from the gravimetric data of sample preparation. The estimation of the laboratories' performance is based on the recoveries of these target concentrations and is, therefore, independent of the number of participants per round.

Reference 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 PT samples 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 samples at different concentration levels are distributed to the laboratories in each laboratory comparison round.

Based on extensive quality assurance measures during the sample production, we can ensure high accuracy of the target concentrations. In each round the correctness of the reference values, homogeneity and stability of the PT samples are checked. For this purpose samples are randomly selected and analysed for the target compounds before sample dispatch and after the closing date. The results of these measurements are presented in the reports.

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