Integration of three-phase microelectroextraction sample preparation into capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science
• Biochemistry

Background:

• Capillary electrophoresis (CE) excels at small sample injection (<100 nL), posing a challenge for analyzing large-volume (20–1500 µL) or dilute samples.
• Electromigration-based sample preparation methods share principles with CE and offer potential for overcoming sample volume limitations.
• Integrating sample preparation with CE is crucial for enhancing the analysis of trace analytes in complex matrices.

Purpose of the Study:

• To demonstrate the coupling of three-phase microelectroextraction (3PEE) with capillary electrophoresis (CE) for effective sample preparation and preconcentration.
• To validate the 3PEE-CE system for the analysis of biogenic amines (serotonin, tyrosine, tryptophan) in biological samples.
• To assess the performance of the integrated system in terms of sensitivity, linearity, and reproducibility.

Main Methods:

• Developed a novel setup coupling three-phase microelectroextraction (3PEE) to the inlet of a capillary electrophoresis system.
• Electroextraction was performed from an aqueous phase, through an organic filter phase, into an aqueous droplet at the capillary inlet.
• Analyzed model compounds (crystal violet) and biogenic amines (serotonin, tyrosine, tryptophan) in aqueous solutions and spiked human urine.

Main Results:

• Successfully demonstrated proof-of-concept using crystal violet and validated the method for extracting serotonin (5-HT), tyrosine (Tyr), and tryptophan (Trp).
• Achieved optimized limits of detection of 15 nM for 5-HT and 33 nM for Tyr, with good linearity (R² > 0.9967) and satisfactory reproducibility (RSD < 14%).
• Successfully extracted and separated 5-HT, Tyr, and Trp from spiked human urine samples, demonstrating applicability to real biological matrices.

Conclusions:

• The coupled 3PEE-CE system effectively addresses the sample volume mismatch in CE, enabling preconcentration of large samples.
• This integrated approach shows significant potential for sensitive bioanalysis and metabolomics studies, particularly for dilute analytes in biological fluids.
• The method requires minimal adaptation of standard CE equipment, suggesting its practical utility and broad applicability in analytical laboratories.