Liquid-Liquid Microextraction Techniques in Food and Environmental Analysis

Liquid-liquid microextraction encompasses a suite of miniaturised sample-preparation methods that transfer target analytes from aqueous, food or environmental matrices into a small volume of immiscible solvent. These approaches achieve high enrichment factors, low solvent consumption and rapid throughput, aligning with green chemistry principles. Dispersive liquid-liquid microextraction (DLLME) dominates the field, utilising a ternary mixture of extraction solvent, disperser solvent and sample to generate fine droplets with large collective surface area. Variants have emerged to address diverse analytical challenges, including ionic-liquid based systems that combine extraction and dispersion in a single step, ultrasound-assisted DLLME for enhanced mass transfer, and techniques that obviate centrifugation through solidification of the floating organic droplet. In food analysis, L-L microextraction methods have been applied to pesticide residues in fruits and dairy products, mycotoxins in grains and pharmaceutical contaminants in beverages. Environmental applications target trace organic pollutants, antibiotics and industrial dyes in water, soil and sediment, often coupling microextraction with chromatographic or mass-spectrometric detection. Innovations such as deep eutectic solvents and magnetic nanoparticle-assisted extraction have improved selectivity, sensitivity and automation, enabling routine monitoring of complex matrices with minimal ecological footprint. Future directions include integration with online analysis, reduction of manual steps and expansion into more polar and high-molecular-weight analyte classes.

Research from Nature Portfolio

Recent studies have introduced an ionic-liquid based microextraction approach integrated with functionalised magnetic nanoparticles for simultaneous solid-phase enrichment and liquid-liquid partitioning. Core–shell magnetic particles coated with task-specific ionic liquids selectively capture industrial dyes from water samples, while a dispersive layer of ionic liquid mediates rapid mass transfer. Magnetic retrieval of the sorbent replaces centrifugation, and the enriched phase is directly compatible with high-performance chromatography. Method development has focused on tuning ionic-liquid composition to balance hydrophobicity, viscosity and analyte affinity, as well as optimising nanoparticle size and surface chemistry to enhance reproducibility and reduce processing time. This hybrid technique attains detection limits in the low microgram-per-litre range and demonstrates excellent robustness across diverse water matrices.

Liquid-Liquid Microextraction Techniques in Food and Environmental Analysis publication trend

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

Technical terms

Dispersive liquid-liquid microextraction (DLLME): A microextraction technique that forms a cloudy solution by injecting a mixture of extraction and disperser solvents into a sample, facilitating rapid analyte partitioning into fine extraction droplets.

Ionic liquid: A low-melting, non-volatile salt used as a green extraction solvent with tunable polarity and high solvation capacity for organic and inorganic compounds.

Deep eutectic solvent: A mixture of hydrogen-bond donors and acceptors that forms a eutectic with a melting point lower than that of individual components, serving as an environmentally benign extractant.

Magnetic solid-phase extraction: A sample-preparation approach where magnetic particles functionalised with selective coatings bind analytes, enabling separation via an external magnetic field.

Ultrasound-assisted DLLME: A variant of DLLME that employs ultrasonic waves to promote extraction solvent dispersion and enhance mass transfer efficiency.

Solidification of floating organic droplet (SFO): A DLLME strategy in which the extraction solvent solidifies at low temperature, facilitating easy separation of the enriched phase without centrifugation.

References

1. Advancements in overcoming challenges in dispersive liquid-liquid microextraction: An overview of advanced strategies. TrAC Trends in Analytical Chemistry (2024).
2. Ionic liquid-based dispersive liquid-liquid microextraction combined with functionalized magnetic nanoparticle solid-phase extraction for determination of industrial dyes in water. Scientific Reports (2017).
3. Simultaneous Determination of Sulfonamides Antibiotics in Environmental Water and Seafood Samples Using Ultrasonic-Assisted Dispersive Liquid-Liquid Microextraction Coupled with High Performance Liquid Chromatography. Molecules (2022).
4. A Vortex-Assisted Dispersive Liquid-Liquid Microextraction Followed by UPLC-MS/MS for Simultaneous Determination of Pesticides and Aflatoxins in Herbal Tea. Molecules (2019).