Magnetic ionic liquids as extraction solvents in vacuum headspace single-drop microextraction

Area of Science:

• Analytical Chemistry
• Separation Science
• Environmental Analysis

Background:

• Short-chain free fatty acids (FFAs) are important biomarkers in various biological and environmental samples.
• Existing methods for FFA determination often require complex sample preparation and can be time-consuming.
• Magnetic ionic liquids (MILs) offer unique properties for extraction and separation applications.

Purpose of the Study:

• To introduce and validate a novel vacuum magnetic ionic liquid headspace single-drop microextraction (vacuum MIL-HS-SDME) technique.
• To determine short-chain FFAs in complex matrices like milk samples.
• To compare the performance of vacuum MIL-HS-SDME with atmospheric pressure methods.

Main Methods:

• Development of a vacuum MIL-HS-SDME method utilizing a rod magnet to stabilize the MIL microdroplet under reduced pressure.
• Optimization of MIL selection, extraction conditions (temperature, time, agitation), and sample matrix (NaCl concentration).
• Analysis of extracted FFAs using gas chromatography-mass spectrometry (GC-MS) after static headspace desorption.

Main Results:

• The trihexyl(tetradecyl)phosphonium tris(hexafluoroacetylaceto)manganate(II) MIL was identified as the most suitable for FFA extraction.
• Vacuum conditions significantly enhanced extraction efficiency and reduced equilibrium times compared to atmospheric pressure methods.
• The method demonstrated wide linearity, low detection limits (down to 14.5 µg L⁻¹), good reproducibility (RSD < 13%), and recoveries (79.5–111%).

Conclusions:

• Vacuum MIL-HS-SDME is a highly efficient and sensitive method for the determination of short-chain FFAs.
• The use of reduced pressure accelerates the extraction process and improves overall analytical performance.
• The method was successfully applied to the quantification of FFAs in real milk samples, showcasing its practical applicability.