Analysis of Organic acids by UV method

Significance of the topic

Accurate quantification of organic acids is essential across food science, biotechnology, pharmaceutical quality control, and environmental monitoring. Their high polarity and structural similarity present challenges for chromatographic separation. Developing a robust reversed-phase method with reliable UV detection addresses demands for routine analysis of these compounds in diverse matrices.

Objectives and Study Overview

This study evaluates the performance of the Shim-pack GIST C18-AQ column for simultaneous analysis of seven common organic acids by UV detection. The goal is to demonstrate sharp peak shapes, good retention, and baseline separation under optimized conditions suitable for routine laboratory applications.

Methodology and Instrumentation

Ultrahigh-performance liquid chromatography was carried out using the Shimadzu Nexera Series.

• Column: Shim-pack GIST C18-AQ HP, 250 mm × 3.0 mm I.D., 3 μm particle size
• Mobile phase: 10 mmol/L sodium phosphate buffer, pH 2.6
• Flow rate: 1.0 mL/min
• Column temperature: 40 °C
• Injection volume: 4 μL
• Detection wavelength: UV at 210 nm
• Sample preparation: Aqueous standards of formic, pyruvic, malic, lactic, acetic, citric, and succinic acids were injected at concentrations between 10 and 100 mg/L.

Main Results and Discussion

The method achieved baseline separation of all seven acids within a single run, with formic acid eluting first followed by pyruvic, acetic, lactic, malic, succinic, and citric acids. Peak symmetry was satisfactory, and retention times showed high reproducibility (RSD <1%). UV detection at 210 nm provided adequate sensitivity for the target concentration range. The use of a low-pH phosphate buffer minimized peak tailing and improved retention of highly polar analytes on the C18-AQ stationary phase.

Benefits and Practical Applications

This protocol offers:

• Efficient separation of structurally similar polar acids
• Short analysis time compatible with high sample throughput
• Routine UV detection without the need for mass spectrometry
• Simplified mobile phase preparation with a single buffer system
• Applicability to quality control in food, beverage, fermentation, and environmental testing

Future Trends and Possibilities

Advances may include coupling this method with mass spectrometric detection to increase sensitivity and selectivity, implementing greener buffer systems, exploring sub-2 μm particle or core–shell columns to further reduce run times, and integrating automated sample preparation for high-throughput analysis. Tailoring stationary phases for improved retention of ultra-polar compounds and miniaturized systems for point-of-care testing are also promising directions.

Conclusion

The Shim-pack GIST C18-AQ column combined with a simple phosphate buffer mobile phase and UV detection provides a reliable, reproducible, and efficient approach for the simultaneous analysis of key organic acids. This method meets routine laboratory requirements for robustness and ease of use.

References

• Application News L578, Shimadzu Corporation, First Edition Dec. 2021.