Exploitable results
The project intends to improve the state of the art of modern polar pesticides in water and to give a mean of verifying the quality of the determinations performed by producing a suitable reference material (CRM).
Modern polar pesticides are used in agriculture as herbicides and it is now recognized that these compounds stringly contaminate the aquatic system (surface and ground waters). Consequently, EC directives have been implemented to regulate the maximum permissible levels in water (0.1/ug/1). In order to control the quality of pesticide determination in water and hence give support to the directive, CRMs are needed. The project consists of preparing a candidate CRM of (freeze-dried) water containing seven polar pesticides. The following tasks will be carried out:
- Preparation of a freeze-dried water candidate CRM containing polar pesticides;
- bottling of the powder obtained after homogenization;
- production of ca. 6000 bottles;
- verification of the between-bottle homogeneity (after reconstitution of the solution)
and long term stability;
- certification via intercomparison
Achievements : The exercise was very helpful for the Commission as it allowed to detect unexpected difficulties due to the addition of glycine. It also demonstrated that the behavior of some pesticides changed during freeze-drying and during the reconstitution of samples when decreasing the concentration and when changing the composition of the water (ionic strength, anionic composition).
It has been stressed by many participants that a CRM containing glycine could not be of any benefit for their QC systems as it is not adapted to their normal routine methods.
Therefore, several participants advised the Commission to reconsider the approach and to possibly come back to freeze-dried samples without glycine. Therefore, the list of pesticides would be reduced. The stability and homogeneity of the material has to be examined in extensive studies before any certification is started. Extrapolation from previous studies on different water materials is not possible without risk
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