Analysis of organic acids on an Agilent InfinityLab Poroshell 120 HILIC-Z column

Significance of Topic

Polar and charged organic acids play critical roles in food and beverage quality control, nutritional analysis and fermentation monitoring. HILIC methods address the challenges of retaining and resolving small polar compounds that are poorly separated by reversed-phase chromatography.

Objectives and Study Overview

This study demonstrates a fast UHPLC method for baseline separation of ten common organic acids using an Agilent InfinityLab Poroshell 120 HILIC-Z column and an Agilent 1290 Infinity LC system. The goal was to achieve high resolution in under five minutes with robust performance suitable for routine analysis.

Methodology and Instrumentation

The method employed a 2.1×100 mm, 2.7 µm superficially porous Poroshell 120 HILIC-Z column operated isocratically with a mobile phase of 30 mM sodium phosphate buffer (pH 6.7) and acetonitrile in a 30 : 70 ratio. Flow rate was 0.5 mL/min, injection volume 0.1 µL, column temperature 30 °C and UV detection at 214 nm. The Agilent 1290 Infinity LC configuration included a low-dispersion binary pump, mixer, high-performance autosampler, thermostated column compartment and diode array detector. Standards of acetic, butyric, lactic, citric, ascorbic, sorbic, succinic, fumaric, oxalic and trans-aconitic acids were prepared in acetonitrile–water mixtures.

Results and Discussion

All ten organic acids were baseline resolved in four minutes with sharp symmetrical peaks and high efficiency. Phosphate buffer minimized baseline noise at low-wavelength detection, and premixing prevented salt precipitation. The zwitterionic HILIC-Z stationary phase delivered excellent peak shape for charged analytes and consistent retention in mid-pH conditions.

Benefits and Practical Applications

This rapid HILIC approach offers high throughput with minimal sample preparation and long-term robustness. It is ideal for routine quality control in food and beverage laboratories, environmental screening and clinical metabolomics. Superficially porous particles lower system backpressure while maintaining high resolution and sensitivity.

Future Trends and Opportunities

Emerging directions include coupling with mass spectrometry for enhanced selectivity, applying volatile formate or acetate buffers for MS compatibility, and extending analyses to broader polar metabolite classes. Automation of sample handling and data processing will further boost throughput and reproducibility.

Conclusion

The Agilent InfinityLab Poroshell 120 HILIC-Z column combined with a simple isocratic phosphate–acetonitrile mobile phase achieves fast, robust baseline separation of multiple organic acids in under five minutes, providing significant advantages for routine analysis of small polar compounds.

Reference

Mack A Analysis of organic acids on an Agilent InfinityLab Poroshell 120 HILIC Z column Application Note 5991-8985EN Agilent Technologies 2018