Method validation and analysis of halogenated natural products (HNPs) in seafood samples

Halogenated natural products (HNPs) are a diverse group of organohalogen compounds, predominantly found in the marine environment. Selected HNPs show structural similarity to persistent organic pollutants (POPs), but data on their occurrence is limited. An analytical method for the detection of 17 commonly reported HNPs, as well as selected POPs, using gas chromatography with electron-capture negative ionisation mass spectrometry (GC/ECNI-MS) was established and validated for salmon and blue mussel. The validation confirmed the applicability of the method with recovery rates and inter-day coefficients of variations of 52-101% and 3.7-16%, respectively. The subsequent application of the method to 17 samples of frequently consumed seafood products from the German retail market demonstrated its suitability for a wide variety of matrices. HNPs were detected in all analysed samples, with contents ranging from <0.05 to up to 7000 ng/g lipid weight (lw). Highest median values were found for mixed-halogenated compound 1 (MHC-1), 2,4,6-tribromoanisole (2,4,6-TBA), and the heptachlorinated bipyrrole Q1 (19, 6.0, and 3.4 ng/g lw, respectively). In 14 out of 17 analysed samples, the sum of HNPs was in the same concentration range or exceeded the sum of the investigated POPs, indicating the relevant exposure of consumers of seafood products in Germany to HNPs and emphasising the relevance of HNPs as organohalogen compounds in seafood samples.