scholarly journals Comparison of Thermal and Flow-Based Modulation in Comprehensive Two-Dimensional Gas Chromatography—Time-of-Flight Mass Spectrometry (GC × GC-TOFMS) for the Analysis of Base Oils

Separations ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 70
Author(s):  
Haleigh A. Boswell ◽  
Matthew Edwards ◽  
Tadeusz Górecki

Base oils are produced by refining crude oil or through chemical synthesis. They are a key component of engine oils. With an immense range of carbon numbers and boiling points, analyzing such complex mixtures is very difficult. The need to monitor industrial petroleum processing steps, as well as to identify petrochemical environmental pollutants, drives the search for improved characterization methods. Comprehensive two-dimensional gas chromatography (GC × GC) is one of the best tools for that. The modulator used in GC × GC is responsible for trapping/sampling the first dimension (1D) column analytes, then reinjecting them in the form of narrow bands onto the second dimension (2D) column for further separation. Modulators used today generally fall into two categories, thermal and flow ones. Heater-based thermal modulators trap the 1D column effluent at or above ambient temperatures. Flow-based modulators utilize storage loop(s) to collect the 1D effluent, which is subsequently flushed into the second-dimension column for further separation. A single-stage, consumable-free thermal modulator and a reverse fill/flush flow modulator were compared for the characterization of base oils. Both were evaluated on their ability to achieve separation of several conventional and synthetic engine oils components. A reverse column set, polar 1D and nonpolar 2D, allowed group-type analysis of all classes, including linear, branched, and aromatic species. The results show the ability to achieve a comprehensive separation of specific compound classes and the differentiation of engine oil types and manufacturers. Soft ionization assisted in tentative identification of two alkylated diphenylamines in each sample. The advantages and limitations of both thermal and flow modulation are presented.

2012 ◽  
Vol 1255 ◽  
pp. 202-206 ◽  
Author(s):  
Sonja Stadler ◽  
Pierre-Hugues Stefanuto ◽  
Jonathan D. Byer ◽  
Michał Brokl ◽  
Shari Forbes ◽  
...  

2007 ◽  
Vol 21 (1) ◽  
pp. 286-294 ◽  
Author(s):  
Jacqui F. Hamilton ◽  
Alistair. C. Lewis ◽  
Marcos Millan ◽  
Keith D. Bartle ◽  
Alan A. Herod ◽  
...  

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Elin Näsström ◽  
Nga Tran Vu Thieu ◽  
Sabina Dongol ◽  
Abhilasha Karkey ◽  
Phat Voong Vinh ◽  
...  

The host–pathogen interactions induced by Salmonella Typhi and Salmonella Paratyphi A during enteric fever are poorly understood. This knowledge gap, and the human restricted nature of these bacteria, limit our understanding of the disease and impede the development of new diagnostic approaches. To investigate metabolite signals associated with enteric fever we performed two dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC/TOFMS) on plasma from patients with S. Typhi and S. Paratyphi A infections and asymptomatic controls, identifying 695 individual metabolite peaks. Applying supervised pattern recognition, we found highly significant and reproducible metabolite profiles separating S. Typhi cases, S. Paratyphi A cases, and controls, calculating that a combination of six metabolites could accurately define the etiological agent. For the first time we show that reproducible and serovar specific systemic biomarkers can be detected during enteric fever. Our work defines several biologically plausible metabolites that can be used to detect enteric fever, and unlocks the potential of this method in diagnosing other systemic bacterial infections.


Química Nova ◽  
2012 ◽  
Vol 35 (5) ◽  
pp. 982-987 ◽  
Author(s):  
Samantha S. Barbosa ◽  
Felipe D. Leal ◽  
Monica C. Padilha ◽  
Raphael S. F. Silva ◽  
Henrique Marcelo G. Pereira ◽  
...  

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