Selective electromembrane extraction at low voltages based on analyte polarity and charge

Area of Science:

• Analytical Chemistry
• Separation Science
• Electrochemistry

Background:

• Electromembrane extraction (EME) is a sample preparation technique.
• Investigating EME under low-voltage conditions is crucial for developing milder analytical methods.
• Understanding the influence of compound properties on EME efficiency is essential for method optimization.

Purpose of the Study:

• To investigate the feasibility and selectivity of low-voltage (0-15 V) electromembrane extraction for basic drug substances.
• To determine the impact of compound physicochemical properties (logP, number of basic groups, polar surface area) on extraction efficiency at low voltages.
• To compare low-voltage EME performance with conventional voltage levels and assess its reliability for complex matrices.

Main Methods:

• Electromembrane extraction (EME) was performed on 29 basic model drug substances.
• Low voltages (0-15 V) were applied, with comparisons to 50 V.
• Extraction efficiency and compound selectivity were evaluated based on logP, number of basic groups, and polar surface area.
• Analyses were conducted using complex biological matrices including human plasma, urine, and breast milk.

Main Results:

• Drug substances with logP<2.3 were not extracted at voltages <15 V.
• Extraction of substances with logP≥2.3 and two basic groups was suppressed at voltages <15 V.
• Substances with logP≥2.3 and one basic group were extracted with high selectivity, influenced by polar surface area.
• Recoveries for this group ranged from 0-23% at 5 V and 5.5-51% at 15 V.
• Selective extractions from plasma, urine, and breast milk were demonstrated based on mass transfer differences.

Conclusions:

• Low-voltage EME is a selective technique for specific basic drug substances.
• Physicochemical properties significantly influence extraction efficiency under mild conditions.
• Reliable analytical data can be obtained using low-voltage EME, offering a gentler alternative to conventional methods.