Experiences with carrier-mediated transport in liquid-phase microextraction

Area of Science:

• Analytical Chemistry
• Separation Science
• Pharmaceutical Analysis

Background:

• Liquid-phase microextraction (LPME) is a sample preparation technique.
• Efficient extraction of hydrophilic basic drugs requires suitable carriers.
• Optimization of carriers is crucial for complex matrices like human plasma.

Purpose of the Study:

• To evaluate diverse organic compounds as extraction carriers in three-phase LPME.
• To investigate the efficacy of ion-pairing for extracting hydrophilic basic drugs.
• To assess carrier compatibility with biological matrices, specifically human plasma.

Main Methods:

• Three-phase LPME utilizing a polypropylene hollow fiber.
• Employing various organic borates, phosphates, sulfates, and carboxylic acids as carriers.
• Utilizing n-octanol or peppermint oil as the organic liquid membrane.
• Analysis of hydrophilic basic drugs through ion-pair complex formation.
• Testing water-soluble (e.g., 1-heptanesulfonic acid) and water-insoluble carriers (e.g., DEHP/TEHP mixture).
• Optimization and validation using bromthymol blue with human plasma samples.

Main Results:

• 1-Heptanesulfonic acid showed promise as a water-soluble carrier.
• A mixture of di(2-ethylhexyl) phosphate (DEHP) and tris(2-ethylhexyl) phosphate (TEHP) demonstrated efficiency as water-insoluble carriers.
• Bromthymol blue exhibited compatibility with human plasma, yielding 45-75% extraction recoveries for eight model drugs.
• Validation studies confirmed acceptable data for phenylpropanolamine and practolol extraction from plasma using bromthymol blue.

Conclusions:

• Organic carriers, particularly bromthymol blue, are effective for three-phase LPME of basic drugs from plasma.
• Ion-pairing is a viable mechanism for extracting hydrophilic basic drugs.
• The developed method shows potential for pharmaceutical analysis in biological samples.