Tandem mass spectrometric identification of eicosanoids: Leukotrienes and hydroxyeicosatetraenoic acids

The product ion spectra of the fast atom bombardment (FAB) desorbed [M - H]− ions of leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) have been obtained on a tandem magnetic sector mass spectrometer with introduction by coaxial continuous flow FAB. Upon collisional activation, the product ion spectra of the [M - H]− ions of these derivatives of arachidonic acid reveal structurally informative product ions. The location of the hydroxy groups on the fatty acid chain, and the position and type of the cysteine-containing moiety of the LTs, can be readily determined from the product ion spectra. Tandem mass spectrometry was used to identify 11-and 15-HETE produced in a low-temperature microsomal enzymatic oxidation of arachidonic acid.