The extract from a shellfish, Neptunea cumingii, showed toxicity to mice. Tetramine (tetramethyl ammonium ion) in the salivary gland was detected with thin-layer chromatography and ion chromatography. The contents of tetramine in the shellfish were determined by two different methods, bio-assay with mice and ion chromatography. These analytical results agreed with each other (γ=0.9848, n=14). Contents of tetramine ranged from 1.6 to 39 mg per shellfish.
