Fig. 7. (A) Collisionally induced dissociation of the deprotonated molecular ion BMSF. The ion at m/z 333 fragments to lose water and CO₂. Ions at m/z155 (OHC.C₆H₁₀.COO^-) and 193 ([C₄H₃O].C₆H₁₀.COO^-), are characteristic; both lose CO₂ under further MS³ dissociation. (B) Electron impact mass spectrum of the methyl ester O-trimethylsilyl ether of BMSF showing ions at m/z 492 (M⁺.), 351 and 243 are characteristic of an 8,X-diHEPE. (C) Catalytic hydrogenation of the A₂₄₀ material results in the formation of 8,13-dihydroxy eicosanoic acid, with characteristic ions at m/z 502 (M⁺.), 201, 245, 322, 359 and 403.