Analysis of Organic Acids

Importance of the Topic

The quantification of organic acids is vital in food and beverage quality control, environmental monitoring, and pharmaceutical research. Precise profiling of carboxylic acids informs process optimization, safety assessments, and compliance with regulatory standards.

Objectives and Study Overview

This application note demonstrates a robust ion-exclusion chromatography method for simultaneous separation and detection of 28 organic acids at 500 mg/L each. The aim is to achieve baseline resolution within a single analytical run, illustrating method performance on Shimadzu’s Nexera Organic Acid system.

Methodology and Instrumentation

An isocratic ion-exclusion approach was implemented using p-toluenesulfonic acid-based mobile phase buffered with Bis-Tris and EDTA. Separation leverages the differing acidity and ionic sizes of target analytes.

• Chromatographic system: Shimadzu Nexera Organic Acid system
• Analytical column: Shim-pack SCR-102H (300 mm × 8.0 mm I.D.) with guard column SCR-102H (50 mm × 6.0 mm I.D.)
• Mobile phase composition: 5 mmol/L p-toluenesulfonic acid, 20 mmol/L Bis-Tris, 0.1 mmol/L EDTA
• Flow rate: 0.8 mL/min
• Column temperature: 45 °C
• Injection volume: 20 µL
• Detection: Conductivity detector

Key Results and Discussion

All 28 organic acids, including formic, acetic, citric, tartaric, succinic, and fumaric acids, were baseline-separated within 50 minutes. The chromatogram exhibits sharp peaks and consistent retention times, highlighting column reproducibility. Early eluters (formic to malonic acid) appear between 5–20 minutes, while larger di- and tri-carboxylic acids elute later. Conductivity detection provided sensitive response for low-ionic-strength analytes.

Benefits and Practical Applications

This method offers high resolution and reproducibility, simplified sample preparation, and compatibility with routine QA/QC workflows. It is well suited for:

• Beverage and fermentation monitoring
• Metabolite profiling in biotechnology
• Environmental water analysis
• Pharmaceutical impurity testing

Future Trends and Potential Applications

Advances may include gradient elution to shorten run times, coupling with mass spectrometry for enhanced identification, micro-flow systems for reduced solvent consumption, and automated sample handling to increase throughput. Integration with data analytics will further refine method sensitivity and selectivity.

Conclusion

The ion-exclusion method using Shim-pack SCR-102H on the Nexera Organic Acid system provides a reliable, high-throughput solution for comprehensive organic acid analysis. Its robust performance supports diverse industrial and research applications.

References

• Application News 01-00171 (JP), Shimadzu Corporation, First Edition Dec. 2021