Simultaneous analysis of inorganic anions, organic acids, amino acids and carbohydrates using the Agilent Basic Anion Buffer

Significance of the topic

Accurate profiling of inorganic anions, organic acids, amino acids and carbohydrates is critical in food and beverage analysis for quality control, nutritional assessment and process monitoring. This CE-based approach enables simultaneous quantification of multiple analytes in a single run, reducing analysis time and resource consumption.

Goals and Overview

This study aims to demonstrate the extension of the Agilent Basic Anion Buffer for a comprehensive screening method combining inorganic anions, organic acids, amino acids and carbohydrates. The method leverages high-pH conditions and reversed electroosmotic flow to achieve effective separation and uses indirect UV detection to visualize low-chromophore species.

Methodology and Instrumentation

High-pH buffer: pre-formulated Agilent Basic Anion Buffer PN 5064-8209.
Capillary electrophoresis system: fused silica capillary 50 µm i.d., 104 cm effective length, 112.5 cm total in an Agilent CE platform.
Operating conditions:

• Injection: pressure injection at 50 mbar for 6 s sample, followed by post-injection of buffer at 50 mbar for 4 s
• Voltage: -30 kV negative polarity to reverse EOF
• Capillary temperature: 15 °C
• Detection: indirect UV at 350/20 nm signal, 230/10 nm reference

Sample preparation involves dilution in deionized water, protein removal via 30 kDa centrifugal filters for complex matrices, and buffer vials prepared in glass to avoid carbonate adsorption.

Main Results and Discussion

The method resolved 43 analytes, including seven inorganic anions, various organic acids, 16 amino acids and 15 carbohydrates. All species were baseline separated except the Leu Ile pair, and arginine can be observed when prepared in alkaline medium. Effective electrophoretic mobilities were determined at 20 °C, with inorganic anions ranging from -7.18 to -4.08 x10-4 cm2 V-1 s-1 and carbohydrates between -0.98 and -0.06 x10-4 cm2 V-1 s-1. Reproducibility tests (n=5) yielded migration time RSDs below 0.3% and peak area RSDs between 0.6% and 5.4%.

Benefits and Practical Applications

This unified CE method significantly reduces analysis time and sample preparation effort by combining multiple analyte classes into one run. It is demonstrated for complex samples such as soy sauce and pineapple juice, achieving clear separation and quantification of key taste-determining compounds such as citrate, malate and sugars for quality control in food industries.

Future Trends and Potential Applications

• Integration with mass spectrometry for enhanced sensitivity and structural elucidation
• Development of tailored reagent kits to improve resolution of closely migrating species
• Automation and online sample preparation to increase throughput
• Application to environmental and bioprocess monitoring by expanding analyte scope

Conclusion

The described CE method using Agilent Basic Anion Buffer provides a robust, high-throughput approach for the simultaneous analysis of diverse anionic species in food and beverage matrices. Its simplicity, reproducibility and broad coverage support its adoption for routine quality control and research applications.

References

• Soga T and Ross GA J Chromatogr A 1997 767 223-230 Agilent 5965-8067E
• Soga T and Heiger DN Anal Biochem 1998 261 73-78 Agilent 5968-0772E
• Soga T and Ross GA J Chromatogr 1999 837 231-239 Agilent 5968-4470E