VLB: Analysis of Organic Acids in Beer by Ion-Exclusion Chromatography and Post-Column pH-Buffering Conductivity Detection

Importance of the Topic

The profile of organic acids in beer has a direct impact on flavor, pH balance and microbial stability, influencing both sensory quality and shelf life. Accurate determination of these acids supports quality control, product consistency and regulatory compliance.

Objectives and Study Overview

This study introduces an ion-exclusion chromatography method combined with post-column pH buffering and conductivity detection to quantify key organic acids in beer. Its aims are to achieve baseline separation, high sensitivity and efficient throughput for routine brewery analysis.

Methodology and Instrumentation

Sample Preparation

• Degassing of beer samples by ultrasonication and tenfold dilution with ultrapure water
• Filtration prior to injection

Chromatographic Conditions

• System: Nexera Organic Acid Analyzer
• Columns: Two Shim-pack SCR-102H columns (300 × 8 mm, 7 µm) in series with guard column
• Eluent: 5 mM p-toluenesulfonic acid
• Reagent: 5 mM p-toluenesulfonic acid 0.1 mM EDTA•4H 20 mM BIS-TRIS
• Flow rates: 0.8 mL/min for both eluent and reagent
• Column oven temperature at 50 °C
• Detection by conductivity cell at 53 °C
• Injection volume 20 µL, run time 35 minutes

Main Results and Discussion

• Baseline resolution achieved for citric, pyruvic, malic, succinic, lactic, formic, acetic and pyroglutamic acids
• Limits of detection between 1 and 6 µM with linear calibration from 0.05 to 2 mM
• Precision of retention time and peak area below 2 percent relative standard deviation
• Quantified organic acid concentrations in five beer samples reflecting diverse fermentation profiles
• Overlap injection function reduced per-run analysis time by 13 minutes from the second injection onward

Benefits and Practical Applications

• Reliable organic acid profiles support flavor optimization and process control in brewing
• High sensitivity and reproducibility facilitate compliance with quality standards
• Automated overlap injection enhances laboratory throughput

Future Trends and Possibilities of Application

• Development of faster column chemistries and higher flow rates for reduced run times
• Integration with mass spectrometric detection for compound confirmation
• Miniaturized or on-site systems for rapid quality checks
• Data analytics and chemometric tools for comprehensive fermentation monitoring

Conclusion

The presented ion-exclusion chromatography method with post-column pH buffering and conductivity detection offers a robust and sensitive approach for profiling organic acids in beer. Baseline separation and low detection limits enable accurate quality assessment while time-saving features improve operational efficiency.

Reference

• Anderson H E Santos I C Hildenbrand Z L Schug K A Analytica Chimica Acta 1085 1–20 2019
• Shimadzu Application News No 01-00171-EN Nexera Organic Acid Analysis System and its Application
• Shimadzu Technical Report C190-E237A High-Speed Analysis of Organic Acids Using Shim-pack Fast-OA and pH-Buffered Electrical Conductivity Detection