Separation of a Mixture of Vitamin K Isomers Using a Solid Core HPLC Column at Sub-ambient Temperature

Significance of Topic

Vitamin K analysis is critical for quality control in pharmaceuticals, nutritional supplements, and biochemical research. Accurate separation of vitamin K1 and K2 isomers supports reliable quantification, informs on bioavailability, and ensures product consistency.

Objectives and Study Overview

The primary aim was to develop a rapid, high-resolution method for separating vitamin K1 cis/trans isomers and vitamin K2 (menaquinone-4) using a solid-core HPLC column under sub-ambient conditions. The study evaluated temperature and flow rate effects on retention, resolution, and system backpressure.

Methodology and Instrumentation

The method employed a Thermo Scientific Accela UHPLC system equipped with an Accucore C30 2.6 µm, 100 × 2.1 mm column.

• Mobile phase: 4% water / 96% methanol isocratic
• Column temperature: optimized at 15 °C
• Flow rates: evaluated 250–500 µL/min
• Injection: 2 µL partial loop, wash solvent 20:80 water/acetonitrile
• Detection: UV at 250 nm

Main Results and Discussion

Vitamin K2 eluted first, followed by the trans and cis isomers of K1. Optimal resolution of the K1 isomers was achieved at 15 °C; higher temperatures (>20 °C) led to co-elution. Increasing flow rate reduced analysis time from under 6 minutes down to under 4 minutes at 500 µL/min, while preserving baseline resolution and maintaining backpressures within standard HPLC limits. Replicate injections (n = 6) at 350 µL/min and 15 °C demonstrated excellent retention time precision (CV ≤ 0.1%) and consistent resolution (1.79 ± 0.2%).

Benefits and Practical Applications

• Fast throughput: complete separation in under 6 minutes.
• High shape selectivity: clear cis/trans isomer resolution.
• Low backpressure: compatible with conventional HPLC systems.
• Robustness: stable performance in aqueous mobile phases.

Future Trends and Possibilities

Further method acceleration can be explored via higher flow rates or shorter columns. Expanding this approach to other lipid-soluble vitamins and carotenoids may benefit nutritional analysis and lipidomics. Integration with mass spectrometry could enhance sensitivity and compound identification.

Conclusion

The Accucore C30 column at sub-ambient temperature provides a rapid, efficient, and reproducible separation of vitamin K1 and K2 isomers, supporting high-throughput analysis in research and QA/QC environments.