Arsenolipids represent a relevant step in the biosynthesis of organoarsenicals from inorganic arsenic compounds. Their fate after human consumption is still uncertain.

By means of a HPLC-ICP-MS/ESI-Q-TOF-MS method, 16 lipid soluble arsenic compounds, including seven formerly unknown organoarsenicals, have been identified in commercial herring fillet.

The structural assignment was done by exact mass and high resolution MS/MS data. This is the first identification of arsenolipids in herring (Clupea harengus). They contribute with (3.6±0.2) mg kg⁻¹ arsenic to 62.3% of the total arsenic content of (5.7±0.3) mg of arsenic per kg dry mass. Current studies indicate that a metabolization by humans to cancerous dimethylarsinic acid is very likely. The presented results are highly relevant as herring is a very popular food fish species in Europe. Moreover, the screening of different fish species revealed that arsenolipids are more widespread than previously assumed.