A strategy to modulate the electrophoretic behavior in plastic microchips using sodium polystyrene sulfonate.

Area of Science:

• Analytical Chemistry
• Separation Science
• Polymer Chemistry

Background:

• Plastic microchips are widely used in microfluidic devices.
• Poorly defined surface properties of plastic microchips limit their application.
• Efficient separation in microchannels requires controlled electroosmotic flow (EOF).

Purpose of the Study:

• To investigate the use of an anionic polymer as a background electrolyte (BGE) for stable EOF in plastic microfluidic devices.
• To improve the electrophoretic separation of biogenic amines (BAs).
• To develop a fast method for BA determination in food samples.

Main Methods:

• Utilized sodium polystyrene sulfonate (PSSNa) as the BGE in cyclic olefin copolymer microchips.
• Generated stable cathodic EOF (∼3.3×10^-4cm²V^-1s^-1).
• Employed capillary electrophoresis coupled with fluorescence detection for BA separation and analysis.

Main Results:

• Achieved efficient separation of fluorescein isothiocyanate labeled BAs within 50s.
• Obtained high theoretical plate numbers (8.0×10⁵/m).
• Confirmed PSSNa's roles as a surface modifier, viscosity regulator, and pseudostationary phase.

Conclusions:

• PSSNa effectively modulates electrophoretic behavior and provides stable EOF in plastic microchips.
• The developed method enables rapid and efficient determination of BAs in complex matrices like fish meat.
• This approach enhances the applicability of plastic microfluidic devices for chemical analysis.