Optimization of extraction procedure for organochlorine pesticides evaluation on shrimp samples

Introduction: Organochlorine pesticides (OCPs) were widespread used around the world and very persistent in the environment. OCPs are, lipophilic, and hydrophobic compounds that can accumulate in biota, become biomagnified through the food chain. Despite several OCPs have been banned, they can still be detected in sediments, plants and animals. Shrimp is one of the most consumed shellfish. It is quite nutritious, rich in proteins, omega-3 fatty acids and a good source of phosphorus, choline, copper, selenium, zinc, iodine, astaxanthin and vitamins. However, they can also accumulate pollutants such as OCPs. The shrimp specie Palaemon serratus is widely distributed in Portugal coastal areas and estuaries, is the subject of small-scale fisheries. Methodology: The OCP residues were extracted by using Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) approach. Three different QuEChERS (AOAC, EN and Original) were tested. The best results were obtained for AOAC QuEChERS. A volume of 1.5mL of prepared aliquot was sampled from the upper layer into a 2-mL centrifuge vial containing a clean-up sorbent with graphitized carbon black. The amount of carbon was optimized in order to use the smaller quantity that are capable of remove the pigments from the samples. An aliquot of the supernatant was transferred to a vial, and the extract was concentrated just to dryness. The sample residue was reconstituted in n-hexane and placed into an auto sampler vial for analysis. The extent of the environmental contamination was reached through the quantification of 14 OCPs by using gas chromatography coupled with electron-capture detector. Results: The limits of detection and quantification obtained were between Endosulfan I (4.7 μg/L and 15.5 μg/L) and β-Hexachlorocyclohexane (10.7 μg/L and 35.5 μg/L) respectively. Recovery testes were made for 20, 30, 40 and 50 μg/L levels. Recoveries ranged from 56% for Hexachlorobenzene and 112% for α- Hexachlorocyclohexane. Conclusion: A simple and faster analytical methodology to analyze pesticides in shrimp samples was developed. Relevance: Shrimp is much appreciated and widely consumed, and for that reason is important to guarantee the safety of these foods.