Method Development for Sample Preparation of Fish for Non-target Analysis of Hydrophobic Organic Pollutants

Sammanfattning: Monitoring methods for environmental pollutants are mostly performed with targeted analysis which relies on predetermined compounds. This can cause an underestimation of possible toxicants as it might not detect undiscovered compounds such as breakdown products of other chemicals. Non-target analysis (NTA) has gained more attraction due to increasing instrumental sensitivity and technological advancements. It attempts to analyze the whole matrix without a prior selection of specific compounds. The aim of this project was to develop a sample preparation method that allows for biomonitoring of organic pollutants in fish using NTA. The method included a broad range of compounds that are suitable for gas chromatography-mass spectrometry (GC-MS) analysis. Five extraction techniques and three clean-up methods were compared using wet weight fish samples and spiked blank samples. The effectiveness of these methods was evaluated based on a selection of 60 compounds that cover the log Kow range of 0.8 to 8.3. The method best equipped for NTA after evaluating recovery and matrix effects was sonication extraction (extracted with a mixture of n-hexane/dichloromethane (DCM)) combined with a deactivated silica clean-up (eluted with n-hexane and DCM). The average recoveries for wet weight fish samples were 99 % for log Kow <5, 65% for log Kow 5-7, and 54% for log Kow ≥7. Semi quantification of nine compounds detected in the non-spiked fish was carried out. The sonication extraction result was statistically similar to the open column extraction but used less solvent than the other sample preparation procedures and was less time consuming. Deactivated silica clean-up is more comprehensive than the commonly used multi-layered silica clean-up and therefore more likely not to discriminate unknown compounds. Further non-target studies using the proposed method is required to evaluate its effectiveness.