Microextractie

Microextractie, or microextraction, is a family of sample preparation techniques that extract trace components from a liquid or solid sample into a very small amount of extraction phase, often enabling simultaneous preconcentration and cleanup. The approach minimizes solvent use and handling compared with traditional liquid-liquid extraction.

Common forms include solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), and various liquid-phase microextraction methods such as single-drop microextraction, hollow-fiber liquid-phase microextraction (LPME), and dispersive liquid-liquid microextraction (DLLME). In SPME and SBSE, a coated solid phase or a coated stir bar adsorbs analytes from the sample; the coating is then thermally or solvent desorbed into a chromatographic instrument. In liquid-phase microextraction, a small solvent phase or sorbent phase is used, often forming a microdrop or being confined inside a hollow fiber, from which analytes are desorbed to gas chromatography or liquid chromatography.

The technique is applied to environmental, food, pharmaceutical, and clinical samples, for compounds such as pesticides, pollutants, drugs, and metabolites. It is compatible with GC-MS and LC-MS and can be automated for high-throughput analysis.

Advantages include reduced solvent consumption, faster preparation, high preconcentration factors, and, in some methods, eco-friendly benefits. Limitations include limited sorbent capacity, potential matrix effects, instrument compatibility requirements, and the need for method optimization for the polarity and volatility of target compounds.

The development of microextraction methods began in the late 20th century with the advent of SPME and SBSE, and has since evolved into numerous variations.