Experimental study of the quantitative precision for valve-based comprehensive two-dimensional gas chromatography

Area of Science:

• Analytical Chemistry
• Chromatography

Background:

• Complex sample analysis demands enhanced separation capabilities in chromatography.
• Comprehensive two-dimensional gas chromatography (GC × GC) has advanced separation science.
• Maintaining quantitative accuracy is crucial alongside increased peak capacity and production.

Purpose of the Study:

• To experimentally investigate the relationship between modulation ratio (M(R)), peak sampling phase (φ), retention time variation (Δt(R)), and quantitative precision (RSD) in valve-based GC × GC.
• To determine optimal parameters for maximizing peak capacity production while ensuring reliable quantitative analysis.

Main Methods:

• Utilized a valve-based GC × GC instrument for experimental analysis.
• Varied the modulation ratio (M(R)) from ~1 to 10 by adjusting the second dimension separation run time (300–2900 ms) while maintaining a constant first dimension peak width (~3 s).
• Conducted a long-term study (35 h) with 126 replicate injections to assess quantitative precision at M(R) of 2.5.

Main Results:

• An average relative standard deviation (RSD) of 2.1% was achieved at an M(R) of 2, enabling a peak capacity production of ~1200 peaks/min.
• RSD increased significantly below an M(R) of 2.
• A long-term study at M(R) 2.5 yielded an average RSD of 3.0% over 35 hours.

Conclusions:

• An M(R) of approximately 2 is optimal for achieving high peak capacity production with excellent quantitative precision in GC × GC.
• These findings enable the optimization of GC × GC methods by allowing longer second dimension run times without compromising quantitative accuracy.