All samples were extracted and cleaned by SPE cartridges using GCB. Carbograph-4 [22,27–30] was supplied by LARA (Rome, Italy).Carbograph-4 is a GCB with a surface area of 210 m2g−1 and particlesize range of 120–400 mesh, similar to Carboprep 200 (Restek) and Envicarb X (Supelco).