microextraction

Microextraction refers to a set of sample preparation techniques designed to extract analytes from complex matrices using minimal or no solvents and to concentrate trace compounds for subsequent instrumental analysis. The approach emphasizes small volumes and often integrates extraction with analysis, reducing solvent waste and enabling rapid processing.

The most common forms are solid-phase microextraction (SPME), liquid-phase microextraction (LPME) and its variants such as single-drop microextraction (SDME), hollow-fiber LPME, and dispersive liquid-liquid microextraction (DLLME). Another widely used approach is stir-bar sorptive extraction (SBSE), which uses a coated stir bar to absorb analytes. SPME uses a fiber or coating that adsorbs analytes from the sample; after exposure, analytes are desorbed into a chromatograph, typically by heating or solvent. LPME employs a very small extraction phase, either a drop of organic solvent (SDME) or a hollow fiber containing solvent, with DLLME dispersing a small amount of extractant in the sample to form droplets that extract analytes rapidly.

History and development: solid-phase microextraction was introduced in the 1990s by Jan Pawliszyn and colleagues, while DLLME was proposed around 2003 by Rezaee and co-workers. Since then, microextraction techniques have been coupled with GC, LC, and MS for a wide range of applications, including environmental monitoring, food safety, clinical analysis, and forensic science.

Advantages and limitations: microextraction offers reduced solvent use, high preconcentration, and compatibility with automated workflows and analytical instruments. Limitations include limited sorbent capacity or extractant volume, potential fragility of coatings or fibers, and matrix effects that can complicate quantification or require careful calibration and method development.