Optimization of extraction procedure for brominated flame retardants evaluation on shrimp samples

Brominated Flame Retardants (BFRs) are mixtures of man-made chemicals applied in high quantity to reduce the flammability of polymers. They are usually used in plastics, textiles and electronic equipment. This group of chemicals consists of tetrabromobisphenol A (TBBPA), polybrominated diphenyl ethers (PBDEs) that comprises 209 congeners, polybrominated biphenyls (PBBs), and hexabromocyclododecane (HBCDD). These compounds are lipophilic and can persist in the environment. The harmful health effects of these chemicals can be related to their persistency, bioaccumulation and biomagnification potential through the food chain 1,2. Since they are lipophilic, they have the capacity to accumulate in animal fats including aquatic species. BFRs have already been found in the atmosphere, sewage sludge, sediments, soils, biota, blood and breast milk. BFRs can act as endocrine disruptors and the continuous human exposure to them are associated with several disorders, including diabetes 1, cancers, neurological effects, thyroid disorders 2 and reproductive disorders 3. Shrimp are one of the most popular consumed seafood in the world and can be a healthy addition to our diet, they are rich in proteins and omega-3 fatty acids. This shellfish is also a good source of phosphorus, choline, copper, selenium, zinc, iodine, carotenoid astaxanthin, as well as B-complex vitamins (B3, B6 and B12), vitamin A and E 4. However, they can also accumulate in pollutants such as BFRs. The shrimp specie Palaemon serratus is widely distributed in Portugal coastal areas and estuaries, is the subject of small-scale fisheries. In this work, the extraction procedure for BFRs in shrimp samples was optimized. For that, 5 g of the edible portion of the shrimp samples were used, and BFRs residues were extracted using Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) approach. Three different QuEChERS were tested: i) AOAC (6 g MgSO4, 1.5 g NaAcetate); ii) EN (4 g MgSO4, 1 g NaCl, 1 g NaCitrate, 0.5 g disodium citrate sesquihydrate; and iii) Original (4 g MgSO4, 1 g NaCl). Two volumes were tested of prepared aliquot: i) 1 mL; and ii) 1.5 mL, sampled from the upper layer into a 2-mL centrifuge vial containing a clean-up sorbent. The clean-up composition was 150 mg MgSO4, 50 mg PSA, 50mg C18, and to the pigments removal it was tested: i) 2 mg of graphitized carbon black and ii) 1mg of multiwalled carbon nanotubes. An aliquot of the supernatant was transferred to a vial, and the extract was concentrated just to dryness. The sample residue was reconstituted with hexane and placed into an auto sampler vial for analysis. The extent of the environmental contamination was reached through the quantification of 12 BFRs [1,2-Dibromo-4-(1,2-dibromoethyl) cyclohexane (TBECH), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), 2-ethylhexyl-2,3,4,5 tetrabromobenzoate (TBB), 1,2‐bis(2,4,6‐tribromophenoxy) ethane (BTBTE) and polybrominated diphenyl ethers 28, 47, 99, 100, 153, 154 and 183] using gas chromatography coupled with electron-capture detector. The best results were obtained using QuEChERS AOAC, clean-up containing 2 mg of graphitized carbon black with 1 mL of prepared aliquot. The recoveries obtained were between 72% and 122%.