Collision-induced dissociation of the M+˙ and [M + H]+ ions of ploycyclic aromatic hydrocarbons produced by keV-ion bombardment

✍ Scribed by Chhabil Dass

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 319 KB
• Volume: 28
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210280435

✦ Synopsis

OMS Letters

Dear Sir,

Collision-induced Dissociation of the M+' and [ M + H] + Ions of Polycyclic Aromatic Hydrocarbons Produced by keV-Ion Bombardment

Polycyclic aromatic hydrocarbons (PAHs) constitute a hazardous class of compounds because of their putative carcinogenic and mutagenic properties. Analysis of these compounds is a challenging task from the viewpoint of the isomerspecificity. Because mass spectrometry (MS) techniques inherently provide a high level of molecular specificity, they have been applied frequently for the analysis of PAHs. By using mixed chemical ionization (CI) with argon/methane as the reagent gas mixture, it was demonstrated that the [M + H]+/M+' ratio is a structure-specific parameter.' The ease of formation of the Diels-Alder cycloadducts with CH2=O+-CH3 reagent ions was used to distinguish anthracene from phenanthrene.' A correlation between the electron affinity (EA) and the electron capture (EC) ionization response was reported; only those PAHs with EA values >0.5 eV produced a molecular anion (M-*) signaL3 The isomer-specific negative-ion chemical ionization (NICI) spectra were obtained for certain P A H s . ~-~ Ion-molecule reactions with reactive reagent gases have also been used for isomer differentiation of isomeric PAHS.',~ Some researchers have used tandem mass spectrometry (MS/MS) for analysis of PAHs.~-' ' Recently, we used fast atom bombardment (FAB)MS for characterization of several PAHs," wherein it was observed that these relatively non-polar compounds are readily ionized when sulfolane, an aprotic molecule, is used as the liquid matrix. A number of PAHs were shown to produce M+' ions in excellent yield, with no evidence of fragmentation. In addition, the [M + HI' ions were also observed. No M+' or [M + HI' ion single is observed when glycerol or any other protic matrix is used. It was further observed that the [M