Fast atom bombardment and collision-induced dissociation of prostaglandins and thromboxanes: Some examples of charge remote fragmentation

Abstract

The mass spectra of products found by collisional activation of selected prostaglandins and thromboxanes were studied by tandem mass spectrometry as barium carboxylate salts and as carboxylate anions. Collision-induced dissociation (CID) of these closed shell ions generated by fast atom bombardment mass spectrometry reveals a wealth of structural information for these hydroxy acids. Decomposition reactions were found to be dependent upon the eicosanoid ring structure and the type of ion being studied, either positive or negative ion. The bariated carboxylate salts undergo reactions by processes that are similar to those previously characterized as charge remote mechanisms in which neutral species are lost as in thermal and photolytic decompositions. The most abundant ion is formed by loss of water from each of the hydroxyl groups present on the prostaglandin or thromboxane structure. For these multifunctionalized eicosanoids, typical patterns of decomposition emerge as characteristic of the oxygen substituents present along the carbon chain of the eicosanoid structure. The structural information obtained from the barium salts along with those from the carboxylate anions is substantially different, yet the structural information from each process is complementary. The CIDs of positive ions (metalated salts) provide structural information concerning the substituents between the carboxyl group and C12 of the eicosanoid structure, whereas the decompositions of the carboxylate anions (negative ion mode) provide data concerning structure alterations of the eicosanoid structure between C15 and C20.

Formation of Highly Reactive A-ring and J-ring Isoprostane-like Compounds (A4/J4-neuroprostanes) in Vivo from Docosahexaenoic Acid

“…A relatively small body of literature exists regarding the characterization of eicosanoids using LC/MS compared with GC/MS. Nonetheless, our present findings are consistent with our previous studies and reports by other investigators (3,(27)(28)(29)(30)(31). As noted, Fig.…”

Mass spectrometric analysis of leukotriene A4 and other chemically reactive metabolites of arachidonic acid

“…Collisional activation of the carboxylate anion (m/z 351) derived from the chemically unstable endoperoxide PGH 2 produced a product ion spectrum ( Figure 5) indistinguishable from the negative ion MS/MS spectra for prostaglandin E 2 and prostaglandin D 2 previously reported [19,20]. Briefly, collisional activation resulted in the loss of one and two molecules of water observed at m/z 333 and 315 as well as the loss of water and carbon dioxide resulting in product ions at m/z 289 and 271.…”

Quantitative high performance liquid chromatography/tandem mass spectrometric analysis of the four classes of F 2 -isoprostanes in human urine

“…So does 17,17,18,18-d 4 -iPF 2␣ -VI. This suggests that the ion at m͞z 115 is the charge-remote vinylic fragment of the molecular ion (35)(36)(37)(38). Its formation includes a process of proton transfer from the hydroxyl group at C5 (Fig.…”