Separation of Sorbate, Benzoate, and Benzisothiazolone on a Thermo Scientific ™ Acclaim™ Mixed-Mode WAX-1 Column

Separation of Sorbate, Benzoate, and Benzisothiazolone on a Thermo Scientific Acclaim Mixed-Mode WAX-1 Column

Importance of the Topic

Preservatives such as potassium sorbate, sodium benzoate and benzisothiazolone are widely used to inhibit microbial growth in food, beverages, cosmetics and industrial formulations. Reliable chromatographic methods are essential to verify compliance with regulatory limits, ensure consumer safety and maintain product quality. The combination of reversed-phase and weak anion-exchange retention mechanisms in a single column offers enhanced selectivity for these anionic compounds.

Objectives and Study Overview

This application note aims to demonstrate the baseline separation of sorbate, benzoate and benzisothiazolone using a Thermo Scientific Acclaim Mixed-Mode WAX-1 column. The focus is on achieving efficient peak shape, short analysis time and low solvent consumption while maintaining method robustness.

Methodology

An isocratic mobile phase consisting of acetonitrile, water, ammonium phosphate buffer and pyrophosphate was used at a flow rate of 0.64 mL/min. Samples spiked at 50 µg/mL each in a model matrix (6 % glycerol + 1 % glucose) were injected in 6 µL volumes. Detection was carried out by UV absorbance at 254 nm. The column temperature was held at 30 °C.

Used Instrumentation

• Column: Thermo Scientific Acclaim Mixed-Mode WAX-1, 3 µm, 3.0 × 150 mm
• LC System: Thermo Scientific Dionex UltiMate 3000
• Detector: UV at 254 nm

Main Results and Discussion

The chromatogram showed baseline resolution of the three preservatives within 9 minutes. Retention times were approximately 3.0 min for sorbate, 5.0 min for benzoate and 7.5 min for benzisothiazolone. Peak efficiency was high, with sharp, symmetric peaks and no coelution. The mixed-mode column allowed fine-tuning of selectivity by adjusting buffer strength and organic content.

Benefits and Practical Applications

• Rapid analysis suitable for high-throughput QC laboratories
• Low organic solvent consumption reduces operating costs and environmental impact
• Robust method applicable to diverse sample matrices in food, beverage and industrial products

Future Trends and Applications

Emerging directions include coupling mixed-mode separations with mass spectrometry for increased sensitivity, miniaturized LC formats for point-of-use testing and further development of green chromatography protocols. Method adaptation for regulatory monitoring of novel preservatives and complex matrices will enhance analytical coverage.

Conclusion

The Thermo Scientific Acclaim Mixed-Mode WAX-1 column provides an efficient, reproducible and versatile solution for separating common anionic preservatives. Its combined retention mechanisms enable rapid baseline separation, making it a valuable tool for routine compliance and quality control analysis.