Simplifying GC×GC Method Development for Implementation in Forensic Fields

When analyzing a complex sample using one-dimensional gas chromatography (1D GC), many analytes will co-elute if they are very similar, so it is difficult to differentiate between two analytes that show up with similar retention times. To address this issue, comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry (GC×GC-TOFMS) is used. This technique uses two columns and a modulator, allowing for more opportunities for the analytes to separate from one another. One drawback of GC×GC is the extensive and daunting method development compared to 1D GC because of the addition of parameters to optimize. Knowing the advantages of GC×GC compared to traditional one-dimensional techniques, the main hindrance to this technique being used in routine applications is the additional parameters that must be addressed during method development. This research aimed to simplify the GC×GC-TOFMS method development process and implement sustainable carrier gas strategies to encourage adoption of this technique. A workflow was developed and tested on forensic samples and chemical warfare agents where nontargeted analysis is helpful because there may not be prior knowledge of the components of a forensic sample. Method translation and development with hydrogen carrier gas was also investigated. These new workflows led to decreased time to a function method, faster run times, increased peak intensity, and more optimal peak shape. Hydrogen carrier gas also provided, on average, about a 50% decrease in runtime, increasing throughput for applications requiring routine analysis. With a more streamlined method development workflow, GC×GC can be a more accessible and sustainable technique used in laboratories, especially ones analyzing forensic evidence.