Arsenic‐Containing Long‐Chain Fatty Acids in Cod‐Liver Oil: A Result of Biosynthetic Infidelity?

tioned between hexane and aqueous methanol, and the polar phase subjected to preparative chromatography with sizeexclusion and anion-exchange media to yield a fraction enriched in polar arsenolipids. Analysis of this fraction by HPLC–inductively coupled plasma mass spectrometry (ICPMS) revealed the presence of at least 15 arsenolipids (Figure 2). Further investigation of the fraction with HPLC– electrospray ionization MS (ESI-MS), under conditions that provided simultaneous detection of elemental arsenic and molecular masses, [3] showed that six of the major arsenicals (A–F in Figure 2) had the following molecular masses: A 334, B 362, C 390, D 418, E 388, and F 436. The mass spectral data for four of these compounds (A–D) were consistent with the presence of a homologous series of arsenic-containing saturated fatty acids of the type (CH3)2As(O)-(CH2)nCOOH (n = 12, 14, 16, and 18) with a dimethylarsinoyl group,