Thermo Scientific Vanquish UHPLC System

Significance of the Topic

Precise control of column and eluent temperature in ultra-high-performance liquid chromatography (UHPLC) is critical for achieving optimal separation efficiency, reproducible retention, and reliable method transfer between instruments. Thermal effects such as viscous heating can induce radial and axial temperature gradients, leading to peak distortion and loss of resolution.

Objectives and Overview of the Study

This application note introduces the Thermo Scientific Vanquish UHPLC system, which integrates an active eluent pre-heater and advanced column thermostatting modes. It aims to demonstrate how these combined features eliminate thermal mismatch, maintain retention factors, and allow users to choose between efficiency optimization and retention reproducibility under varying UHPLC conditions.

Methodology and Instrumentation

Experiments were conducted using a high-efficiency Hypersil GOLD column operated in isocratic mode with 50% acetonitrile in water at 30 °C. Linear velocities ranged from 0.07 to 1.04 mL/min to assess viscous heating effects. Data acquisition was performed with UV detection at 240 nm and 100 Hz.

Used Instrumentation

• Thermo Scientific Vanquish UHPLC system with real-time active eluent pre-heater (1 µL volume)
• Column thermostatting modes: still air and forced air
• Stationary phase: Hypersil GOLD, 1.9 µm, 2.1 × 100 mm
• UV detector: 240 nm, 100 Hz acquisition rate, 4 nm bandwidth

Main Results and Discussion

Van Deemter analysis showed that under high linear velocities, forced air mode removed frictional heat efficiently but resulted in a steeper C-term slope and up to 40% lower efficiency at 880 bar compared to still air. Conversely, still air mode retained frictional heat within the column, suppressing radial gradients and delivering up to 10% higher efficiency and 20% faster optimal analysis speeds at 3 mm/s. Retention factor measurements revealed that forced air maintained consistent k′ values up to and slightly beyond uopt, while still air exhibited decreasing retention with increasing flow rate. These findings highlight the trade-off between peak shape and retention control depending on the chosen thermostatting strategy.

Benefits and Practical Applications

• Still air mode: maximizes separation efficiency and resolution at very high analysis speeds, ideal for superfast UHPLC methods.
• Forced air mode: ensures robust retention reproducibility and smoother method transfer from HPLC to UHPLC or between UHPLC platforms.
• Active eluent pre-heating: minimizes extra-column volume effects and provides precise eluent temperature control up to 120 °C without impacting column efficiency.

Future Trends and Opportunities

Advances in UHPLC temperature control may include predictive thermal management using real-time sensor feedback, integration of machine learning for dynamic thermostatting, and expansion of high-temperature eluent systems for challenging separations. Such developments could further enhance method robustness, reduce development time, and enable novel applications in complex sample analysis.

Conclusion

The Thermo Scientific Vanquish UHPLC system’s combination of active eluent pre-heating and dual-mode column thermostatting effectively addresses thermal mismatch and retention variability. By offering both still air and forced air options, it empowers users to tailor performance for either maximum efficiency or reproducible retention, facilitating reliable method transfer and superior chromatographic outcomes.

References

No references were provided in the original text.