On-Line HP(LC)-GC-FID Determination of Hydrocarbon Contaminants in Fresh and Packaged Fish and Fish Products

BACKGROUND: Fish products can be contaminated with mineral oil hydrocarbons (MOH), mainly as a result of environmental contamination (wild fish) or contaminated feeds (farmed fish). Packaged products may also be contaminated with polyolefin oligomeric hydrocarbons (POH), which, depending on the packaging, storage condition, matrix composition, and fat content, may migrate relatively easily from the packaging to the food.OBJECTIVE: A rapid, solvent-sparing method for determining hydrocarbon contaminants in fish products was developed, validated, and applied to farmed and wild fish products (both fresh and packaged samples, stored under different conditions).METHOD: Microwave-assisted saponification (MAS) was used in combination with on-line LC-GC-flame ionization detection (FID).RESULTS: The proposed method showed quantitative recovery, good repeatability, and high sensitivity. Farmed salmon had variable mineral oil saturated hydrocarbon contamination (from 0.5 to 4.3mg/kg), accompanied by mineral oil aromatic hydrocarbons (maximum 1.4mg/kg), while wild salmons had no detectable contamination. Samples of one farmed salmon and a swordfish, both sliced and packed under vacuum, resulted contaminated with POH migrated from the packaging. POH migration was also evident in a ready-to-eat meal.CONCLUSIONS: The proposed method showed good performance characteristics in terms of recovery, repeatability, and LOQ. Fatty fish products are more prone to contamination with hydrocarbon contaminants.HIGHLIGHTS: MAS allows for rapid and efficient sample preparation. An LC-GC-FID method for MOH/POH determination in fish products was validated. Fish products may be contaminated with variable amounts of hydrocarbon contaminants.