Extraction Of Organic Compounds From Challenging Matrices That Requires Zero Solvents

The GERSTEL Twister enables efficient extraction of organic compounds from aqueous matrices based on Stir Bar Sorptive Extraction (SBSE). SBSE is a solvent-free extraction technique, which is significantly faster than most conventional extraction techniques.

SBSE is up to 1000 x more sensitive than SPME since the stir bar has significantly more sorbent volume and since it can extract, and concentrate analytes from, a much larger sample volume due to the efficient stirring.

Gerstel Twister
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Are you currently carrying out phenols, pesticides, PAHs, PCBs analysis in water and waste water?

Liquid-liquid extraction is that way outdated and almost always results in bad recoveries and dirty sample extracts. Traditional SPE cleanup of 1 lit of water is quite laborious and often results in lower recoveries? Maybe you are using solid phase micro-extraction (SPME) approach and maybe facing an issue of fibers breaking very often?

To do away with all of these problems and increase the efficiency of extraction at least 1000 times compared to SPME we recommend a new generation extraction technology called Stir Bar Sorptive Extraction (SBSE), popularly known as Twister.

The Twister may look like a conventional magnetic stirring rod, but while it stirs samples, such as water, body fluids or beverages it adsorbs and concentrates organic compounds onto its sorbent coating. A large number of samples can be extracted simultaneously using multi-position stir plates resulting in high productivity and throughput. Once the adsorption of the organic molecules onto Twister is complete, Twister then is desorbed into the inlet for the further analysis.

Twister/SBSE Benefits:

  • Up to 1000 times more sensitive than SPME
  • Quantitative, with large linear range
  • A large number of samples can be extracted simultaneously for highest productivity
  • Requires minimal time and labor
  • Thermal desorption and GC/MS analysis are performed in one automated system

Twister Sorbent Phases

PDMS Twister
EG/Silicone Twister 
Phase Polydimethylsiloxane (PDMS) Polydimethylsiloxane (PDMS)/Ethylene glycol (EG) - copolymer on an inert metal grid for mechanical stabilization
EnrichmentUnspecific sorption of apolar compounds log(Kow) > 4
The polarity range can be extended bu adding salt to the sample (salting out).
Unspecific sorption of apolar compounds, additionally specific binding if polar hydrogen bond doners, such as phenols
Application examplesPesticides in water
PAH in marine tissue
2,4,6-TCA in wine
Flavor compounds in food
Flavor compounds in beverages


When the SBSE-step has been completed, the Twister is transferred to either a Thermal Desoption Unit TDU or a Thermal Desorption System TDS. Thermal desorption and GC/MS determination of the concentrated organic compounds are then performed in one integrated system under integrated software control. Using the multi-desorption mode, multiple Twister desorptions can be performed for each GC/MS run resulting in even higher sensitivity and lower limits of detection.


Involatile, polar or thermally labile compounds can be extracted from the Twister with a solvent using TwisterBackExtraxtion TBE for subsequent determination by LC/MS.


  • Food and beverages
  • Flavour and Fragrance
  • Environmental analysis of water (EU-WFD) or waste water
  • Extractables and leachable from pharmaceutical packaging

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