Continuous-flow microelectroextraction for enrichment of low abundant compounds

Area of Science:

• Analytical Chemistry
• Microfluidics
• Electrochemistry

Background:

• Traditional methods for analyzing low-abundance metabolites often require large sample volumes and extensive pre-concentration steps.
• Developing efficient microfluidic devices for analyte extraction is crucial for sensitive and rapid analysis.

Purpose of the Study:

• To introduce a continuous-flow microelectroextraction flow cell for electric field enhanced analyte extraction.
• To demonstrate the stabilization of the interface between flowing and stagnant phases using a phaseguide.
• To assess the device's performance for acylcarnitine extraction and its application in biological samples.

Main Methods:

• Design and fabrication of a continuous-flow microelectroextraction cell with a phaseguide.
• Visual assessment of chip performance using crystal violet.
• Off-line coupling with reversed-phase liquid chromatography-time-of-flight mass spectrometry (RP-LC-TOF-MS) for acylcarnitine analysis.
• Application to urine samples spiked with acylcarnitines.

Main Results:

• Achieved concentration factors of up to 80 times for acylcarnitines from 1 mL samples into 13.4 μL acceptor phase.
• Demonstrated high recoveries (up to 107.8%) for certain acylcarnitines.
• Established low detection limits (0.3-2 nM) for acylcarnitines in spiked urine samples.
• Identified several putative endogenous acylcarnitines in urine.

Conclusions:

• The developed microelectroextraction flow cell effectively concentrates analytes from large volumes, enabling sensitive detection of low-abundance metabolites.
• The phaseguide technology stabilizes the interface, crucial for efficient extraction in flowing systems.
• This method is well-suited for analyzing complex biological samples like urine, offering improved detection limits.