Towards a solution for viscous heating in ultra-high pressure liquid chromatography using intermediate cooling

Area of Science:

• Analytical Chemistry
• Chromatography
• Chemical Engineering

Background:

• Viscous heating in chromatographic systems becomes significant at ultra-high pressures (>1200 bar).
• This heating effect can compromise column efficiency and temperature stability.
• Existing systems face limitations in managing thermal effects at elevated pressures.

Purpose of the Study:

• To propose and validate a generic solution for mitigating deleterious viscous heating effects in adiabatic or near-adiabatic systems.
• To enable stable operation of chromatographic columns at pressures exceeding current ultra-high pressure ranges.
• To investigate the impact of column segmentation and active cooling on system efficiency and temperature stability.

Main Methods:

• A column of length L was segmented into n smaller segments of length L/n.
• Active cooling was applied to the capillaries connecting these segments.
• Proof-of-principle experiments were conducted using existing commercial equipment.

Main Results:

• Column segmentation did not result in significant efficiency loss compared to a standard column.
• The system demonstrated improved temperature stability over time and space, with reduced axial temperature rise.
• The method effectively removed viscous heat at connection points, preventing efficiency loss at the column wall.

Conclusions:

• Column segmentation with active cooling is a viable strategy for managing viscous heating in high-pressure chromatography.
• This technique enhances thermal stability and allows for operation at pressures of 1500 bar and above.
• While promising, complex non-linear effects may moderate improvements in specific applications like pharmaceutical method transfer.