μGC × μGC: comprehensive two-dimensional gas chromatographic separations with microfabricated components

Area of Science:

• Analytical Chemistry
• Separation Science
• Microfluidics

Background:

• Comprehensive two-dimensional gas chromatography (μGC × μGC) offers enhanced separation power for complex mixtures.
• Miniaturization of GC systems is crucial for portable and high-throughput analytical applications.

Purpose of the Study:

• To develop and characterize a microanalytical subsystem for μGC × μGC separations.
• To evaluate the performance of different stationary phases in the second dimension (2D) column.

Main Methods:

• Fabrication of silicon-micromachined separation columns and a thermal modulator (μTM).
• Utilized poly(dimethylsiloxane) (PDMS) for the first dimension and either a room-temperature ionic liquid (RTIL) or OV-215 for the second dimension.
• Employed conventional injection and flame ionization detection with temperature-ramped separations.

Main Results:

• Initial tests with an RTIL stationary phase showed limitations due to strong retention of polar compounds, resulting in broad peaks.
• Switching to an OV-215 stationary phase in the 2D column significantly improved performance.
• A 36-component mixture was successfully separated in 22 minutes, demonstrating modulated peak widths from 90 to 643 ms and modulation numbers of 1-6.

Conclusions:

• The developed μGC × μGC system with an OV-215 coated 2D column is effective for analyzing complex mixtures.
• Stationary phase selection in the second dimension is critical for achieving optimal separation and resolution.
• This microanalytical subsystem shows promise for portable and efficient chemical analysis.