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| From left to right: Marco Reiter, Caroline Stadlmann, Susanne Schemitz, Wolfgang Kandler and Uta Kachelmeier |
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
Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management.
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.
In the year 2009, more than 200 European laboratories participated in our PT scheme.
Successful participation in the scheme is recognised by the
Federal Ministry of Economics and Labour of the Republic of Austria, which holds the accreditation
body for testing laboratories in Austria.
The IFA-Tulln (formerly "Institute for Agrobiotechnology Tulln") is located close to the Danube
river approximately 40 kilometres northwest of Vienna and was opened in 1994. Since 2004 the IFA-Tulln
has become a department of the University of Natural Resources and Applied Life Sciences, Vienna and is
now called "Department for 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.
Since the very beginning, our institute has focused on quality assurance in analytical chemistry.
Our reliable team organizes the PT rounds under the direction of a lab manager.
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| From left to right: Marco Reiter, Caroline Stadlmann, Susanne Schemitz, Wolfgang Kandler and Uta Kachelmeier |
We are steadily improving the accuracy of our analytical methods for the determination of all parameters
in order to check the correctness of the target values even more efficiently.
The concept of measurement uncertainties is now fully integrated in our reports. The uncertainties of the
target values, the quality assurance and stability measurements performed at the IFA-Tulln are given in
the reports.
Our evaluation includes z-scores which are calculated from criteria (s) that are determined from long-term
performance data of all former participating laboratories. Thus, the criteria are known prior to
participation and are independent from single PT rounds.
The evaluation software programme was extended for long-term data evaluation based on z-scores.
We can provide this to all users of the PT scheme as an additional service.
After evaluation of each PT round, every laboratory will receive a confirmation of participation.
It contains the target values, the results, the recoveries, the z-score-criteria (s), the achieved
z-scores and the letter code of the laboratory. For each parameter the z-scores are illustrated in
both tabular and graphical form.
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. 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.
The target 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. 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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