Solid phase microextraction (SPME) is an innovative and sensitive solvent-free sample preparation technology. Based on the principle of adsorption/absorption and desorption, SPME uses a coated fiber to concentrate volatile and semi-volatile compounds from a sample.
SPME is widely used for a variety of applications involving environmental, biological and pharmaceutical samples, foods and beverages, flavors and fragrances, forensics and toxicology and product testing. Typical uses include:
SPME uses a fiber coated with an extraction phase: a liquid (polymer), a solid (sorbent), or a combination of both. The coated fiber is housed in a protective needle and attached to a holder that looks like a syringe.
When the fiber is exposed to a sample, the sample’s analytes partition from the sample matrix into the stationary phase until an equilibrium is established. The fiber’s coating extracts compounds from the sample either by absorption (liquid coatings) or adsorption (solid coatings). After a prescribed extraction time, the fiber is removed and inserted directly into a chromatographic instrument, usually gas chromatography (GC) or HPLC, for desorption and analysis. The desorption in GC of analytes is carried out thermally, whereas HPLC uses a solvent for desorption into a liquid-phase.
SPME combines analyte sampling, isolation, and enrichment into one, simple step. By controlling the polarity and thickness of the fiber coating, maintaining consistent sampling time, and controlling several other extraction parameters, SPME allows an analyst to ensure highly consistent and quantifiable results from samples, even when analytes are at low concentrations.
Other benefits of SPME include:
Conventional SPME is used to extract and concentrate analytes for the purpose of GC analysis. Extraction is carried out either by direct immersion (DI-SPME), where the fiber is directly immersed in the liquid sample, or headspace SPME (HS-SPME), where the fiber is exposed in the vapor phase above a sample.
BioSPME is a bioanalytical microsampling and sample preparation technique used to quickly and selectively extract a broad range of analytes from biological samples while repelling unwanted macromolecules (e.g., lipids, proteins). Subsequent analysis is usually by LC/MS or direct MS. BioSPME operates via direct extraction, involving no sample pretreatment. This provides a non-exhaustive, equilibrium-based extraction, allowing multiple analyses to be performed from the same aliquot.