Condensation nucleation light scattering detection for capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Capillary electrophoresis (CE) offers high-resolution separations but often requires sensitive detection methods.
• Interfacing CE with aerosol-based detectors like condensation nucleation light scattering (CNLS) presents challenges due to low flow rates.

Purpose of the Study:

• To develop and evaluate two novel interfaces for coupling CE with CNLS detection.
• To improve limits of detection (LODs) for analytes separated by CE.

Main Methods:

• A fused-silica capillary with a Nafion membrane and pneumatic nebulizer was tested.
• A PEEK (polyether ether ketone) capillary served as both separation conduit and nebulizer, with conductive paint for grounding.

Main Results:

• The Nafion membrane system yielded LODs in the low microgram per milliliter range for amino acids, limited by background.
• The PEEK capillary system significantly reduced background signals, achieving LODs below 1 μg/mL (<100 fmol) for amino acids and peptides.
• Both systems generated aerosols effectively from low CE flow rates.

Conclusions:

• The PEEK capillary interface offers a simpler and more sensitive approach for CE-CNLS detection compared to the Nafion membrane system.
• These interfaces are effective for aerosol generation in CE and adaptable to other aerosol-based detectors.