The tests carried out in CRA-W's "Treated Seeds" laboratory involve determining the average active substance content on treated seeds, assessing the distribution of this active substance from one seed to another, measuring the quantity of dust and the active substance content in this dust.
The laboratory is also equipped with a device for treating seeds before their characterisation. These tests are carried out at various stages, when formulated products are received, after accelerated ageing and after long-term storage.
To achieve this, the laboratory develops and validates chromatographic methods for identifying and quantifying PPPs. These methods are suitable for both average loadings and seed-by-seed loadings, as well as for analysing PPPs in dust. Optimisation of these processes is mainly focused on pesticide extraction steps using appropriate solvents, as well as analysis by high or ultra-high performance liquid chromatography combined with UV/visible spectrophotometric detection (U/HPLC-DAD) or gas chromatography coupled with flame ionization detection (GC-FID).
These studies, coupled with physico-chemical characterisation studies of the formulated product, provide the data needed to obtain marketing authorisations. They are carried out in accordance with current European regulations (EC Regulation 1107/2009) and in compliance with the OECD Principles of Good Laboratory Practices (GLP). The laboratory has many years' experience in this field, and has developed its skills on a wide range of fungicides and insecticides applied to several types of seed.
Increasing numbers of clients are calling on the laboratory to carry out simultaneous analysis of several active substances using a single extraction and chromatographic method. This type of analysis presents a real challenge, as the active substances may have different physico-chemical properties and be present in very different concentrations on the seed, yet they still need to be accurately quantified. In this context, mass spectrometry may be necessary to achieve the lowest detection thresholds. One of the laboratory's other major challenges involves analysing of volatile substances, such as essential oils, which are also used for seed treatment.
