Comparison of Separation and Selectivity of Nexera™ Organic Acid Analysis System and Reversed Phase-UV Method

Importance of the Topic

Strong and sensitive analysis of low molecular weight organic acids is essential in food quality control, beverage development, environmental monitoring and industrial process management. Accurate quantitation of multiple acidic components supports product consistency, regulatory compliance and metabolic studies.

Objectives and Study Overview

This study evaluates two HPLC approaches for simultaneous multi-analyte determination of organic acids: a conventional reversed phase separation with UV detection and a post-column pH-buffered conductivity detection method. Comparative assessments were performed on standard mixtures and real samples (sports drink and red wine) to gauge speed, selectivity and robustness.

Methodology and Instrumentation

• Reversed Phase-UV Method: Shimadzu Nexera Series, Shim-pack GIST C18-AQ HP column (250×3 mm, 3 μm), mobile phase 10 mM sodium phosphate buffer (pH 2.6), flow rate 1.0 mL/min, column temperature 40 °C, UV detection at 210 nm.
• Post-column Conductivity Method: Nexera Organic Acid Analysis System, two Shim-pack SCR-102H columns (300×8 mm, 7 μm) with guard column, mobile phase 5 mM p-toluenesulfonic acid, buffered reagent (5 mM p-toluenesulfonic acid, 20 mM Bis-tris, 0.1 mM EDTA), flow rate 1.0 mL/min, column temperature 40 °C, conductivity detection.

Main Results and Discussion

• Standard Mixture: Both methods resolved key acids (e.g., phosphoric, citric, malic, lactic, acetic acids) with sharp peaks; UV method offered shorter runtime (~6 min) while post-column method delivered enhanced sensitivity and baseline stability.
• Sports Drink: Low matrix interference allowed reversed phase-UV to achieve satisfactory separation and faster analysis. Conductivity method confirmed peak identities with high reproducibility.
• Red Wine: Complex matrix caused multiple UV-absorbing interferences and extended retention times under reversed phase conditions, reducing reliability. The post-column approach provided high selectivity and clear separation of wine acids in <14 min.

Benefits and Practical Applications of the Method

• UV Method: Rapid screening for low-contaminant samples such as beverages and quality control in food processing.
• Post-column Conductivity Method: Robust quantitation in complex matrices (wine, environmental samples) with minimal interference and improved sensitivity.

Future Trends and Potential Applications

The integration of automated buffering kits and high-throughput sampling can further streamline organic acid profiling. Emerging microbore columns, novel detection schemes (e.g., mass spectrometry coupling), and AI-driven data analysis will enhance method sensitivity, reduce solvent consumption and expand applications in metabolomics and environmental screening.

Conclusion

Both reversed phase-UV and post-column conductivity detection methods offer reliable separation of common organic acids. Method selection should be guided by sample complexity, required throughput and sensitivity needs. Combining these approaches enables versatile workflows across research, industrial and regulatory laboratories.