Assessing wine quality with IC

Importance of the Topic

Organic acids are key determinants of wine quality, influencing aroma, flavor, color and stability. Monitoring their profile supports authenticity assessment, tracks fermentation and aging processes, and ensures compliance with international enological standards.

Objectives and Study Overview

This work presents two ion chromatography methods employing suppressed conductivity detection for comprehensive organic acid and anion analysis in wine. A rapid isocratic screening method targets major organic acids and common inorganic anions, including sulfite. A more detailed binary-gradient approach resolves 15 organic acids for in-depth profiling.

Methodology

Samples of red and white wines were diluted 10–50× with ultrapure water and filtered automatically via inline ultrafiltration through a 0.22 μm regenerated cellulose membrane. Suppressed conductivity detection enabled low-background, high-sensitivity measurements of ionized organic acids and anions.

Instrumentation Used

• 940 Professional IC Vario ONE/SeS/HPG with sequential suppression and binary high-pressure gradient
• IC Conductivity Detector with high temperature stability and DSP signal processing
• Metrosep A Supp 10-100/4.0 column for fast isocratic separations
• Metrosep A Supp 7-250/4.0 column for gradient separations
• 858 Professional Sample Processor for automated injection and inline ultrafiltration
• 800 Dosino and MSM-HC suppressor rotor for automatic suppressor regeneration

Key Results and Discussion

Fast screening (<20 min) separated acetate, malate, tartrate, oxalate and anions chloride, phosphate, sulfite and sulfate. Tartrate was predominant (1 534–1 756 mg/L); RSDs were below 2 %. Gradient analysis resolved 15 organic acids with detection limits of 0.1–5 mg/L. Suppressed conductivity avoided UV interferences from sugars and phenols. Inline ultrafiltration reduced carryover to <0.1 % and protected columns.

Benefits and Practical Applications

• High throughput multi-component screening in a single run
• Automated sample preparation reduces manual labor and error
• Sensitive detection in the lower mg/L range without UV interferences
• Column longevity through inline ultrafiltration
• Flexibility to extend with mass spectrometry for peak confirmation and lower detection limits

Future Trends and Applications

Integration of inline dilution for automated calibration will further streamline workflows. Coupling IC to mass spectrometry can enhance selectivity and sensitivity. Method extensions may include phenolic acid profiling for authenticity verification and real-time monitoring of fermentation. Miniaturized and field-deployable IC platforms could enable on-site quality control.

Conclusion

Ion chromatography with suppressed conductivity detection delivers robust, sensitive and rapid analysis of organic acids and anions in wine. The combination of fast isocratic screening and detailed gradient profiling, together with automated inline ultrafiltration, maximizes laboratory efficiency and analytical performance for enological quality control.

References

1. Waterhouse R., Sacks G., Jeffery D. (2016) Understanding Wine Chemistry. John Wiley & Sons, UK, ISBN 1118627806.
2. International Organization of Vine and Wine (OIV) (2021) Compendium of International Methods of Analysis of Wines and Musts. OIV, France, ISBN 978-2-85038-030-3.
3. Metrohm Application Note WP-065 Simplified sulfite determination in foods and beverages using ion chromatography.