Extraction of Lipids and Polychlorinated Biphenyls from Fish Tissue in a Single Run Using Accelerated Solvent Extraction (ASE)

IntroductIon The presence of polychlorinated biphenyls (PCBs) in fish and other marine organisms is of immediate environmental and regulatory concern. To determine the concentrations of PCBs indicative of contaminant exposure, and lipids, which also characterize physiological conditions of fish, the analytes must first be extracted. Traditionally, this has been done using Soxhlet methods that are both time consuming and use large volumes of solvent. This application note summarizes the use of ASE® to quickly and efficiently extract lipids and PCBs in a single 20 min extraction using only 40 mL of solvent. ASE is an automated extraction technique that uses traditional liquid solvents at elevated pressure and temperature. The extraction is performed at temperatures higher than the atmospheric pressure boiling point of the solvent. High temperature substantially increases solvation kinetics and the high pressure ensures that the solvent remains a liquid. While developing the ASE method, it was determined that water typically found in fish tissue (>70%) can act as a polar solvent and produce coextractables which complicate extract cleanup prior to analysis. It was discovered, however, that drying samples before ASE extraction produced extracts free of troublesome coextractables. Samples can be dried in a conventional oven or, even faster, in a microwave oven after mixing and dispersing with ASE Prep DE (diatomaceous earth). This application note provides full details of the extraction parameters and a comparison of ASE and Soxhlet extraction results. EQuIPMEnt ASE 200 Accelerated Solvent Extractor* equipped with 33 mL extraction cells ASE Solvent Controller (optional) Gas Chromatograph Restek RTX-5 column, 30 m × 0.32 mm i.d., film thickness 0.25 μm Microwave oven (800 W) with carousel Analytical balance Dionex Graduated 40 mL vials for extract collection (P/N 055442) Organomation N-EVAP® Analytical Evaporator (Model 112) or equivalent Screw-on Stainless Steel Funnel (P/N 049288) Cellulose Filter Insertion Tool (P/N 049495) Cellulose Filters (P/N 049458)