Liquid-Phase Microextraction Techniques in Analytical Chemistry

Liquid-phase microextraction (LPME) encompasses a suite of miniaturised solvent-based approaches designed to isolate and pre-concentrate analytes from complex matrices prior to instrumental analysis. By dramatically reducing solvent volumes and sample handling, LPME aligns with green analytical chemistry principles while delivering high enrichment factors, enhanced selectivity and lower limits of detection than conventional liquid–liquid or solid-phase extraction. Key configurations include single-drop microextraction, dispersive liquid–liquid microextraction (DLLME), hollow-fibre liquid-phase microextraction (HF-LPME), solvent-bar microextraction and electromembrane extraction. Recent developments focus on alternative extraction media—such as ionic liquids, deep eutectic solvents and supramolecular solvents—alongside advances in supported liquid membranes and parallel artificial liquid membrane extraction. Applications span environmental monitoring of pollutants and pesticides, residue analysis in food and beverage, trace determination of pharmaceuticals and biomolecules in clinical and forensic samples, and real-time bioanalysis. The versatility of LPME techniques, their amenability to automation and compatibility with hyphenated detection platforms have driven widespread adoption, enabling rapid, cost-effective and environmentally responsible sample preparation across diverse analytical challenges.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Research from all publishers

A comprehensive review of liquid-phase microextraction modes highlights the evolution of DLLME, single-drop microextraction, HF-LPME and electromembrane extraction across environmental, food, pharmaceutical and forensic fields. The analysis underscores the integration of green solvents—nanostructured supramolecular solvents, deep eutectic solvents and ionic liquids—as key enablers for enhanced selectivity and reduced ecological footprint, and presents case studies of automated and high-throughput platforms. A study on membrane-based LPME has defined the optimal extraction window for three-phase supported liquid membranes using deep eutectic solvents as carrier phases. By systematically varying analyte polarity (log P), membrane aromaticity and ionic carrier content, recoveries up to 98 percent were achieved for non-polar compounds within log P 2–5, while the inclusion of an ionic carrier broadened the window to polar analytes (log P –0.5 to 2). This work establishes design principles for tailored membrane selection in pharmaceutical and environmental assays. In the realm of bioanalysis, a comparison of hollow-fibre LPME and parallel artificial liquid membrane extraction for aromatic amines demonstrates superior recoveries and automation potential of the latter. Under optimised conditions, the parallel approach achieved high sensitivity, low limits of detection and rapid throughput in urine samples, confirming its promise as a green alternative to conventional liquid–liquid extraction in toxicological and clinical applications.

Liquid-Phase Microextraction Techniques in Analytical Chemistry publication trend

The graph below shows the total number of articles in liquid-phase microextraction techniques in analytical chemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Dispersive liquid–liquid microextraction (DLLME): A technique in which a mixture of extraction and disperser solvents is rapidly injected into an aqueous sample to form a cloudy solution of fine droplets, facilitating rapid mass transfer and phase separation.

Hollow-fibre liquid-phase microextraction (HF-LPME): A three-phase system using a porous fibre membrane impregnated with extraction solvent to isolate analytes from sample into an internal acceptor solution.

Single-drop microextraction (SDME): A method in which a single solvent droplet is suspended at the tip of a microsyringe in the sample to extract analytes by diffusion.

Electromembrane extraction (EME): An electrically driven LPME technique employing an applied potential across a supported liquid membrane to transport ionised analytes selectively.

Deep eutectic solvent (DES): A class of green solvents formed by hydrogen-bonded mixtures of quaternary ammonium salts and hydrogen-bond donors, used as extraction media with tunable polarity.

Supported liquid membrane (SLM): A porous barrier impregnated with an extraction solvent that separates donor and acceptor phases, enabling selective analyte transfer.

Parallel artificial liquid membrane extraction (PALME): A multi-well format of membrane-based LPME in which each well contains a supported liquid membrane, allowing high-throughput extraction of multiple samples simultaneously.

References

1. Overview of Different Modes and Applications of Liquid Phase-Based Microextraction Techniques. Processes (2022).
2. Membrane-based liquid-phase microextraction of basic pharmaceuticals – A study on the optimal extraction window. Journal of Chromatography A (2021).
3. Liquid-phase microextraction of aromatic amines: hollow fiber–liquid-phase microextraction and parallel artificial liquid membrane extraction comparison. Analytical and Bioanalytical Chemistry (2023).