Analysis of Distilled Spirits Using an Agilent J&W DB-WAX Ultra Inert Capillary GC Column

Importance of the Topic

Accurate characterization of volatile congeners in distilled spirits is crucial for quality control, flavor profiling, and regulatory compliance in the beverage industry. High water and ethanol content in these samples often challenge traditional GC columns, leading to peak tailing, poor reproducibility, and column degradation. An inert capillary GC phase can overcome these issues, enabling more reliable quantification of alcohols, aldehydes, and organic acids.

Objectives and Study Overview

The primary goal of this application note was to evaluate the performance of the Agilent J&W DB-WAX Ultra Inert (UI) GC column when analyzing distilled spirits with high water content. Key aims included:

• Assessing peak shape and retention time stability for problematic congeners.
• Demonstrating column inertness and phase stability through repeated injections.
• Comparing performance in different GC configurations and sample matrices.

Methodology and Instrumentation

Two GC/FID systems were employed under defined conditions:

• System 1: Agilent 7890B with helium carrier at 0.7 mL/min, split ratio 30:1, temperature program 40 °C to 200 °C (36 min run).
• System 2: Agilent 7890B with hydrogen carrier at 2.5 mL/min, split ratio 20:1, temperature program 35 °C to 240 °C (total 20 min run).

Autosampler: Agilent 7683B, 0.5 µL injection. Key consumables included the DB-WAX UI column (30 m × 0.25 mm, 0.25 µm), ultra-inert split liner, nonstick septa, and Vespel/graphite ferrules. Samples of Chinese liquor and Maker’s Mark bourbon were analyzed neat.

Key Results and Discussion

Chromatograms of a Chinese spirit revealed sharp, symmetrical peaks for methanol, higher alcohols (e.g., propanol, butanol), esters, aldehydes, and organic acids. Baseline separation was achieved for ethyl acetate vs. acetal and for 2-pentanol vs. ethyl valerate—compounds that coelute on standard PEG columns. Over 200 injections of a 38% ethanol/62% water spirit, retention time drift was negligible and peak shapes remained consistent, confirming phase inertness.
An overlay of the first and 50th injections of neat bourbon maintained peak integrity for alcohols, aldehydes, and acids, demonstrating the column’s robustness in aqueous matrices.

Benefits and Practical Applications

• Enhanced quantification accuracy for trace congeners in spirits quality control.
• Extended column lifetime and consistent performance in high-water samples.
• Improved resolution of closely eluting flavor compounds for sensory profiling and product development.

Future Trends and Potential Applications

Advances in inert column chemistries will further reduce analyte interactions, enabling:

• High-throughput screening of flavored beverages by GC/MS with minimal maintenance.
• Integration with automated headspace systems for routine QC labs.
• Expansion into other aqueous food and beverage matrices with challenging analytes.

Conclusion

The Agilent J&W DB-WAX Ultra Inert capillary column provides superior inertness and stability for direct analysis of distilled spirits containing high water content. It delivers consistent retention times, sharp peak shapes, and reliable quantification of alcohols, aldehydes, and organic acids across hundreds of injections, making it an ideal choice for flavor analysis and quality assurance in the beverage industry.

References

1. Piggott, J. R. Whisky, Whiskey and Bourbon: Composition and Analysis of Whiskey. Encyclopedia of Food and Health, Elsevier, 2016.
2. Shurtleff, W.; Aoyagi, A. History of Koji-Grains and/or Soybeans Enrobed with a Mold Culture. Soyinfo Center, 2012.
3. Zheng, Y. et al. Analysis of volatile compounds of Bandaojing sesame-flavor liquor. Food Sci. 2014, 35, 60–65.
4. Lynam, K. Agilent J&W DB-624 Ultra Inert Capillary Column Screens Distilled Spirits by GC/MS Headspace; Application note, Agilent Technologies, Inc., 2012.