Determination of Volatiles in Liquors by GC-FID with Dual Acquisition System

Importance of the topic

Volatile organic compounds in distilled beverages contribute significantly to aroma and taste, but some pose health risks if present above safety thresholds. Reliable, high‐throughput analytical methods are essential for quality control and regulatory compliance in spirit production.

Objectives and Overview of the Study

This work demonstrates the use of a dual acquisition GC‐FID system (Shimadzu Nexis GC‐2030) for the simultaneous analysis of two groups of volatiles in liquors. By dividing target analytes into two mixtures and employing two independent columns, the approach minimizes downtime and avoids manual column switching.

Methodology and Instrumentation

Sample Preparation:

• Calibration standards prepared in 40% (v/v) ethanol at 30, 150, 300, and 600 ppm.
• Internal standard: 300 ppm 3-pentanol spiked into all standards and samples.
• Liquor samples analyzed directly by liquid injection.

Instrument Configuration:

• Shimadzu Nexis GC‐2030 with Dual AOC-20i/s autosampler and two FID detectors.
• Column 1: Rtx-502.2 (30 m × 0.25 mm × 1.4 µm film) for Mixture 1.
• Column 2: SH-Stabilwax (30 m × 0.32 mm × 1 µm film) for Mixture 2.
• Carrier gas: Helium at linear velocities of 36 cm/s (Mixture 1) and 57.8 cm/s (Mixture 2).
• Injection: Split mode (10:1), 0.5 µL volume, 200 °C, high‐pressure injection to avoid backflash.

Main Results and Discussion

Both mixtures were baseline‐resolved with sharp peaks. Calibration curves for all compounds exhibited excellent linearity (R2 > 0.9997). Two commercial liquors were analyzed: common fusel alcohols, esters, and aldehydes were quantified. Methanol levels of 177.5 ppm and 37.7 ppm in the two samples were below the EU agricultural spirit limit of 200 ppm, confirming safety. Trace detection of isopropanol and acetone was negligible, indicating no contamination.

Benefits and Practical Applications

This dual GC‐FID configuration allows:

• Continuous operation without manual column or detector changes.
• Rapid, accurate quantification of a broad range of volatile analytes.
• Effective prevention of injector backflash when analyzing high‐water content samples.

It is particularly suited for routine QA/QC in distilleries and flavor profiling in laboratories.

Future Trends and Opportunities

Advancements may include coupling this dual system with mass spectrometry for enhanced identification, expanding target compound lists, and integrating automated data processing for real‐time monitoring. Miniaturized or portable dual‐column GC systems could further streamline field testing.

Conclusion

The dual acquisition GC‐FID method on Nexis GC‐2030 provides a robust, efficient workflow for volatile analysis in spirits, combining high sensitivity, excellent linearity, and minimized downtime. This approach meets industry needs for flavor characterization and safety assurance.

References

[1] Dragone C., Mussatto S.I., Covico C., Teixeira J.A., Characterisation of volatile compounds in alcoholic beverage produced by whey fermentation, Food Chemistry 112 (2009) 929–935.
[2] Paine A., Dayan A., Defining a tolerable concentration of methanol in alcoholic drinks, Human & Experimental Toxicology 20 (2001) 563–568.