Solid-Phase Microextraction (SPME)
Definition
Solvent-free extraction in which a fused silica fibre coated with a stationary phase is exposed to the sample or its headspace, and the fibre is desorbed directly into a GC injector.
- Mechanism
- Fused silica fibre coated with a stationary phase absorbs analytes
- Sampling mode
- Direct immersion or headspace exposure
- Solvent use
- Solvent-free extraction
- Detection
- Fibre desorbed directly into a GC injector
Common questions
Why is headspace SPME favoured for fire debris and volatile analysis?+
Sampling the vapour above a specimen avoids exposing the fibre to nonvolatile matrix contaminants and concentrates volatile ignitable-liquid components onto the coating before thermal desorption, which improves sensitivity for trace accelerant residues without solvent extraction steps.
What limits the range of compounds SPME can recover from a sample?+
Recovery depends on the fibre coating's affinity for a given analyte class and on the analyte's volatility and polarity, so a single fibre type does not extract all compound classes equally well and coating choice is matched to the target analytes.
Related terms
- Accelerated Solvent Extraction (ASE)
- Extraction of solid matrices at 100 to 200 degrees Celsius and around 1500 psi in sealed stainless steel cells. Also called pressurised...
- Dried Blood Spot (DBS)
- Sampling format in which 50 microlitres of capillary blood is spotted on Whatman 903 paper, dried and shipped at ambient temperature.
- HPTLC
- High-performance TLC with smaller silica particles, automated Camag Linomat band application and densitometric scanning that delivers quantitative results comparable to HPLC.
- Mixed-Mode SPE
- Sorbent that combines reverse-phase and ion-exchange chemistry on the same particle. Strata-X-C, Oasis MCX and Bond Elut Certify are the cation-exchange forms...
- Solid-Phase Extraction (SPE)
- Sample clean-up in which analytes are retained on a packed bed of bonded silica or polymer, interferences are washed off, and analytes...