Pressure-Driven Chromatographic Separation Modes in Self-Enclosed Integrated Nanocapillaries

Area of Science:

• Nanofluidics
• Chromatography
• Separation Science

Background:

• Nanofluidic channels are crucial for high-resolution separations.
• Pressure-driven chromatography offers efficient sample analysis.
• Diverse cross-sectional geometries impact separation performance.

Purpose of the Study:

• To investigate the pressure-driven chromatographic separation characteristics of nanofluidic channels with varying cross-sectional geometries.
• To compare the performance of cylindrical, triangular, and rectangular nanocapillaries.
• To evaluate the potential for analyzing ultra-low volume samples.

Main Methods:

• Fabrication of self-enclosed nanocapillaries (cylindrical, triangular) using semiconductor processing.
• Chromatographic separation experiments in 10 mm long nanocapillaries under various modes (normal-phase, reversed-phase, ion-valence, hydrodynamic).
• Analysis of van Deemter plots and plate heights based on linear mobile phase velocity.

Main Results:

• Excellent agreement between experimental and theoretical plate heights for 300 nm radius capillaries and 750 nm deep slits.
• Minimum plate heights below 2 μm and theoretical plate numbers in the order of 10^5 plates/m achieved.
• Cylindrical nanocapillaries, particularly 300 nm radius, exhibit high resolving power.

Conclusions:

• Robust, self-enclosed nanocapillaries are suitable for pressure-driven chromatographic analysis.
• Nanofluidic channels enable high-efficiency separation of minute sample volumes.
• The demonstrated technology facilitates advanced analytical capabilities for single-cell analysis.