Towards exhaustive electromembrane extraction under stagnant conditions.

Area of Science:

• Analytical Chemistry
• Separation Science
• Electrochemistry

Background:

• Electromembrane extraction (EME) offers potential for in-field analysis but is limited by evaporative losses in open systems.
• Previous stagnant EME designs suffered from reduced performance due to sample and acceptor evaporation.

Purpose of the Study:

• To develop and optimize a completely closed stagnant electromembrane extraction system.
• To evaluate the extraction efficiency of basic drugs from aqueous solutions and whole blood.
• To assess the suitability of the optimized system for in-field applications.

Main Methods:

• Utilized a laboratory-made polyoxymethylene (POM) well plate for sample and a filter plate for the supported liquid membrane (SLM) and acceptor.
• Investigated and optimized design parameters (compartment, electrode geometry) and operational parameters (sample volume, voltage, time).
• Coupled the optimized EME system with liquid chromatography-mass spectrometry (LC-MS) for analysis.

Main Results:

• Optimized conditions (50 μL sample, 60 min, 75 V) achieved exhaustive extraction from buffer (75-87% recovery).
• Extraction from whole blood yielded slightly lower recoveries (57-96%).
• LC-MS analysis of methadone in blood met regulatory requirements (LOD: 0.4 ng/mL, LOQ: 1.4 ng/mL).

Conclusions:

• The developed closed stagnant EME system effectively minimizes evaporative losses.
• The optimized system demonstrates improved performance and potential for reliable in-field drug analysis.
• This advancement brings stagnant EME closer to practical field deployment.