Optimisation of Pressurized Liquid Extraction for the Determination of Seven Selected Polychlorinated Biphenyls in Feed Samples

Pressurized Liquid Extraction was utilized for the extraction of seven selected polychlorinated biphenyls (28, 52, 101, 118, 153, and 180) from a naturally contaminated fishmeal and two feed samples fortified with a naturally contaminated fish oil sample. In order to assure sufficient extraction efficiencies, the extraction solvent, the extraction temperature, and the flush volume were optimised by a factorial design approach. The results of the analyses revealed that the impact of these parameters on the extraction of PCBs differed depending on which matrix that was analysed. For fishmeal, an elevated extraction temperature was important to obtain the highest values for the recovery rates whereas for the feed samples high extraction efficiencies could be obtained for all temperatures investigated in the study. In addition, the solvent had an impact on the extraction of PCBs, however, the influence was less pronounced than the impact of temperature. The final conditions, resulting in high recovery rates for all PCBs in all matrices, were found to be temperatures above 100°C using n-heptane as extraction solvent, while the flush volume had very limited effects on the extraction efficiency.