A robust and extendable sheath flow interface with minimal dead volume for coupling CE with ESI-MS.

Area of Science:

• Analytical Chemistry
• Separation Science
• Mass Spectrometry

Background:

• Capillary electrophoresis-mass spectrometry (CE-MS) interfaces are crucial for sensitive analysis.
• Minimizing interface dead volume is essential for improving separation efficiency and detection sensitivity.
• Existing sheath flow interfaces often suffer from significant dead volume, limiting performance.

Purpose of the Study:

• To develop a robust sheath flow-based CE-MS interface with minimal dead volume.
• To enhance the separation efficiency, detection sensitivity, and working reliability of CE-MS.
• To provide a simple and robust interface for routine analytical applications.

Main Methods:

• Utilized a fused-silica capillary as both separation capillary and electrospray emitter.
• Employed an extendable sheath-flow interface mode with a surface sheath flow.
• Optimized parameters including capillary extending distance, emitter diameters, sheath flow capillary shape, and flow rate.

Main Results:

• Achieved a minimal interface dead volume of approximately 4 pL, the smallest reported for sheath flow-based CE-MS interfaces.
• Demonstrated high separation efficiency (2.07–3.38 µm plate heights) and good repeatabilities (< 6.1% RSD) for peptide mixture separation.
• The developed interface showed enhanced working reliability and sensitivity.

Conclusions:

• The novel sheath flow-based CE-MS interface significantly reduces dead volume, improving analytical performance.
• This simple and robust interface offers a viable alternative for commercial CE-MS development.
• The interface has potential applications in proteomics, metabolomics, and single-cell analysis.