Performance Characteristics of a Comprehensive GCxGC-High Resolution TOFMS System Utilizing Chemical Ionization
Poster May 22, 2015
Jonelle Shiel, Mark Merrick, Scott Pugh, Matthew Soyk, and Viatcheslav Artaev
Comprehensive two-dimensional gas chromatography (GC×GC) is a powerful tool which leads to dramatically improved separation for complex samples. This technique generates very narrow chromatographic peaks, requiring a high speed detection system to accurately represent the chromatographic separation in two-dimensional space. When combined with a rapid acquisition High Resolution Time-of-Flight Mass Spectrometer (HRTOFMS), the resulting accurate mass data provides additional information for compound identification.
A soft ionization source, which generates mostly molecular or quasi molecular ions, further enhances the information available by allowing for the unambiguous, or nearly unambiguous, identification of the elemental composition of compounds of interest. Conventional Electron Ionization (EI) sources used for MS detection systems generate multiple fragment ions and can limit the formation of the parent ion of interest. Incorporating Chemical Ionization (CI) can greatly assist in maintaining the molecular or quasi molecular ion relative to the typically used EI source. This work demonstrates the performance of a GC×GC-HRTOFMS with a CI source.
The LECO Pegasus® GC-HRT 4D supports standard CI reagent gases, including methane, isobutane, and ammonia, while also allowing for custom gases to be chosen. To assist in optimization of the ion source, both automated and manual reagent gas flow optimizations are available. In addition, the instrument allows for simple exchange of the ion source between CI and EI.
The data presented includes: Benzophenone standards to demonstrate the instrument’s performance regarding detection limit, linear dynamic range, precision, resolution, and mass accuracy. A 10% Diesel sample is also included to demonstrate the two-dimensional separation capability of the instrument.