Peak capacity optimization in comprehensive two dimensional liquid chromatography: a practical approach.

Area of Science:

• Analytical Chemistry
• Chromatography
• Separation Science

Background:

• Comprehensive two-dimensional liquid chromatography (LC x LC) is a powerful separation technique.
• Optimizing LC x LC requires balancing parameters like column dimensions, flow rates, and mobile phase composition.
• Under-sampling, where peaks are not adequately resolved between dimensions, can significantly limit separation efficiency.

Purpose of the Study:

• To develop a practical optimization approach for LC x LC using a gradient Poppe method.
• To incorporate under-sampling correction into the optimization strategy.
• To investigate the impact of under-sampling on peak capacity and identify optimal operating conditions.

Main Methods:

• Applied a gradient implementation of the Poppe approach for peak capacity optimization.
• Incorporated under-sampling correction into the optimization model.
• Considered gradient elution in both dimensions with practical constraints on mobile phase composition.
• Analyzed four classes of solutes with different retention properties.

Main Results:

• The under-sampling effect significantly impacts LC x LC optimization, leading to counter-intuitive results.
• Optimal effective LC x LC peak capacity can be achieved when the first dimension is run under sub-optimal conditions.
• The optimal sampling rate is slower than previously reported and increases with longer first-dimension gradient times.

Conclusions:

• Under-sampling correction is crucial for accurate LC x LC optimization.
• Deliberately operating the first dimension under sub-optimal conditions can paradoxically improve overall peak capacity.
• The findings provide new insights into optimizing sampling rates and gradient times for enhanced LC x LC performance.