Determination of organochlorine pesticides adsorbed on plastic pellets

In the past years, several studies have revealed the presence of organic contaminants at concentrations from sub ng g–1 to mg g–1 on/in plastic pellets found in coastal environment worldwide [1,2,3]. Plastic pellets are actually industrial raw material, typically in the shape of small granules with a diameter of a few mm. They are categorized as microplastics (< 5 mm). They can be unintentionally lost in the environment during manufacturing and transport. They can subsequently reach the marine and coastal compartments. Due to their environmental persistence, they are widely distributed in the oceans and on beaches [1]. Organic pollutants associated to pellets are either additives (e.g. PBDEs) that are incorporated into plastics during production processes or hydrophobic chemicals (e.g. PCBs, organochlorine pesticides) which adsorb from the surrounding environment (e.g. seawater). Among these chemicals, some are recognized as POPs (Persistent Organic Pollutants) because of their persistence, bioaccumulation and potential adverse environmental and health effects. Thus, in order to better assess the impact of plastic pellets in coastal environment, it is necessary to determine the level of associated organic pollutants. The present study was carried out in the frame of DeFishGear project, which focuses on marine litter and microplastics issues in Adriatic region. This investigation aimed at developing an experimental protocol allowing the quantification of 11 organochlorine pesticides. Plastic pellets, sampled on beaches located in the Adriatic region, were first sorted by colour. Pesticides were extracted from the plastic matrix (c.a. 0.5 g) in a pressurized fluid extractor (50°C, 100 bar). Prior to evaporation, the extract was cleaned on Florisil sorbent through solid-phase extraction (SPE). The concentrated extracts were quantified on gas chromatography equipped with a micro electron capture detector (GC-μECD). Preliminary results revealed the presence of DDT transformation products.