Task3: Measurements of persistent organic pollutants (organochlorine pesticides) The analytical methodology used for measuring the targeted organochorine pesticides is derived from procedures previously developed, validated, and accredited for other classes of lipophilic persistent organic pollutants such as dioxins and PCB compounds. Briefly, a preliminary step using accelerated solvent extraction (ASE) will be followed by successive purification stages on activated silica and celite columns. The measurement will be performed using gas chromatography coupled to high resolution and/or tandem mass spectrometry (GC-HRMS, GC-MS/MS). The quantification will be achieved according to the isotopic dilution method (i.e. using 13C labeled analogous as internal standards). The selection of the main targeted substances will be preliminary based on the Stockholm convention that lists about 12 major pesticides of concern.