Secondary ozonides of substituted cyclohexenes: a new class of pollutants characterized by collision-induced dissociation mass spectrometry using negative chemical ionization.
Recent studies indicate that secondary ozonides of cyclic alkenes are formed in atmospheric reactions and may be relatively stable. The secondary ozonides (SOZs) of cyclohexene (1), 1-methylcyclohexene (2), 4-isopropyl-1-methylcyclohexene (3) and 4-isopropenyl-1-methylcyclohexene (limonene) (4) have been characterized by rapid gas chromatography electron ionization (EI), negative and positive chemical ionization (CI: ammonia, isobutane and methane) and collision-induced dissociation (CID) mass spectrometry. Both EI and positive CI spectra were found unsuitable for reproducible analysis. However, negative CI showed stable (M-H)(-) ions with minor fragmentation. CID of the (M-H)(-) ions resulted in simple and reproducible fragmentation patterns for all four SOZs with loss of m/z 18, 44 and 60, tentatively assigned as H(2)O, CO(2) and C(2)H(4)O(2) or CO(3), respectively. Thus, negative CI-MS-MS in combination with rapid gas chromatography is the preferred method for identification of secondary ozonides of cyclohexenes.
Nørgaard
Asger W
AW
Indoor Environment Group, National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen Ø, Denmark.
Nøjgaard
Jacob K
JK
Clausen
Per A
PA
Wolkoff
Peder
P
D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D053138:Cyclohexenes / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006571:Heterocyclic Compounds / Q000032:analysis* / Q000737:chemistry; D053719:Tandem Mass Spectrometry
C503429:1,2,4-trioxane; D000393:Air Pollutants; D053138:Cyclohexenes; D006571:Heterocyclic Compounds