Very high pressure liquid chromatography using core-shell particles: quantitative analysis of fast gradient...

Area of Science:

• Analytical Chemistry
• Chromatography

Background:

• Rapid gradient separations in very high pressure liquid chromatography (VHPLC) face challenges with column thermal stability due to high flow rates and pressures.
• Uneven thermal effects and the need for thermal equilibrium restoration between analyses impact efficiency.

Purpose of the Study:

• To investigate methods for controlling mobile phase flow rate to minimize thermal instability in VHPLC.
• To achieve reproducible gradient separations without post-run equilibration times.

Main Methods:

• Evaluated five mobile phase flow rate control methods for gradient elution in VHPLC.
• Tested constant flow rates, constant pressure operations (two sets), programmed flow constant pressure, and constant net heat loss at the column wall.
• Assessed reproducibility using six replicate gradient separations of a nine-component RPLC standard mixture.

Main Results:

• Constant flow rates, programmed flow constant pressures, and constant heat loss at the column wall yielded reproducible separations.
• Programmed flow under high constant pressure reduced analysis time by 16% compared to constant flow rate methods.
• No post-run equilibration time was needed for reproducible data in constant flow rate, programmed flow constant pressure, and constant wall heat experiments.

Conclusions:

• Effective control of mobile phase flow rate is crucial for thermal stability and reproducibility in rapid VHPLC gradient separations.
• Programmed flow constant pressure is an efficient method, reducing analysis time and eliminating the need for post-run equilibration.
• These findings enable faster and more reliable analytical workflows in VHPLC.