| Title: | Molecular Characterization of Volatiles and Petrochemical Base Oils by Photo-Ionization GCxGC-TOF-MS |
| Author(s): | Giri A; Coutriade M; Racaud A; Okuda K; Dane J; Cody RB; Focant JF; |
| Address: | "University of Liege , Department of Chemistry, Organic & Biological Analytical Chemistry Group, Allee du 6 aout, B6c, B-4000 Liege (Sart Tilman), Belgium. Total Marketing Services, Centre de Recherche de Solaize , Chemin du Canal-BP 22, 69360 Solaize, France. Jeol U.S.A. , 11 Dearborn Road, Peabody, Massachusetts 01960, United States" |
| DOI: | 10.1021/acs.analchem.7b00124 |
| ISSN/ISBN: | 1520-6882 (Electronic) 0003-2700 (Linking) |
| Abstract: | "The characterization of organic mixtures by comprehensive two-dimensional gas chromatography (GCxGC) coupled to electron impact (EI) ionization time-of-flight mass spectrometry (TOF-MS) allows the detection of thousands of compounds. However, owing to the exhaustive fragmentation following EI ionization, despite the use of mass spectral libraries, a majority of the compounds remains unidentified because of the lack of parent ion preservation. Thus, soft-ionization energies leading to organic compounds being ionized with limited or no fragmentation, retaining the molecular ion, has been of interest for many years. In this study, photoionization (PI) was evaluated as the ion source for GCxGC-TOF-MS measurements. First, capabilities and limitations of PI were tested using an authentic mixture of compounds of several chemical classes. Ionization energy exhibited by PI, equivalent to 10.8 eV, resulted in significant retention of molecular ion information; [M](+*) for alkanes, ketones, FAMEs, aromatics, [M-H](+*) for chloroalkanes, and [M-H(2)O](+*) for alcohols. Second, considering the potential of PI for hydrocarbons, base oils, complex mixtures of saturated and unsaturated hydrocarbons blended for finished lubricant formulations, were extensively evaluated. Several chemical classes of hydrocarbons were positively identified including a large number of isomeric compounds, both aliphatics and cyclics. Interestingly, branched-alkanes were ionized with lower excess internal energy, not only retaining the molecular ions but also exhibiting unique fragmentation patterns. The results presented herein offer a unique perspective into the detailed molecular characterization of base oils. Such unprecedented identification power of PI coupled with GCxGC-TOF-MS is the first report covering volatiles to low-volatile organic mixtures" |
| Notes: | "PubMed-not-MEDLINEGiri, Anupam Coutriade, Marion Racaud, Amandine Okuda, Koji Dane, John Cody, Robert B Focant, Jean-Francois eng 2017/04/15 Anal Chem. 2017 May 16; 89(10):5395-5403. doi: 10.1021/acs.analchem.7b00124. Epub 2017 Apr 26" |
