High-Speed Analysis of Organic Acids Using Shim-pack Fast-OA and pH-Buffered Electrical Conductivity Detection

Importance of the Topic

Organic acids play critical roles in food quality control, pharmaceutical formulations, biomass fermentation and metabolic research. Rapid and selective analysis of these compounds is essential for real-time process monitoring, quality assurance and efficient adjustment of bioprocess parameters.

Objectives and Study Overview

The main goal of this study was to develop a high-speed analytical method for quantifying organic acids in complex samples. By combining the Shimadzu Shim-pack Fast-OA high-speed organic acid column with post-column pH-buffered electrical conductivity detection, the investigators sought to shorten analysis time while maintaining sensitivity and selectivity.

Methodology and Instrumentation

• Column setup: Shim-pack Fast-OA column (100 mm × 7.8 mm I.D., 5 µm) with guard column; up to three columns in series for enhanced resolution.
• Mobile phase: 5 mmol/L p-toluenesulfonic acid; post-column buffer: 5 mmol/L p-toluenesulfonic acid, 20 mmol/L Bis-Tris, 0.1 mmol/L EDTA.
• Flow rate: 0.8 mL/min for both mobile phase and buffer; column temperature varied between 35 °C and 50 °C.
• Detection: Shimadzu CDD-10AVP conductivity detector equipped with a high-efficiency microreactor mixer and PEEK and stainless steel tubing for post-column buffering.
• Injection volume: 10 µL.

Main Results and Discussion

Using a single Fast-OA column, 25 organic acids eluted within 10 minutes at 45 °C, with retention times shifting predictably with temperature. Connecting two or three columns in series improved peak resolution for closely eluting acids such as lactic and formic acids. Calibration in culture media demonstrated linear response (R2>0.999) over 1–100 mg/L for key acids. Analysis cycle times were reduced to under 10 minutes for standards and under 20 minutes for complex samples, enabling efficient high-throughput workflows.

Benefits and Practical Applications

This method delivers rapid, sensitive and selective detection of organic acids in samples containing high levels of interferents. It supports real-time fermentation monitoring, intestinal flora studies, biomass energy research, food quality testing and pharmaceutical counterion analysis, while reducing solvent consumption and improving laboratory throughput.

Future Trends and Opportunities

Future developments may include integration with automated bioprocess control systems, miniaturized column formats, coupling with mass spectrometry for structural insights, and expansion into metabolomics and environmental monitoring. Novel buffer systems and column chemistries could further enhance speed and resolution.

Conclusion

The combination of Shim-pack Fast-OA high-speed columns with post-column pH-buffered conductivity detection provides a powerful platform for fast, selective and robust organic acid analysis in complex matrices, offering significant benefits for industrial and research laboratories.

References

Nakashima M., Koterasawa K. High-Speed Analysis of Organic Acids Using Shim-pack Fast-OA and pH-Buffered Electrical Conductivity Detection. Shimadzu Technical Report C190-E237A, 2019.