Gerstel logo

Twister/Stir Bar Sorptive Extraction SBSE

Extraction without solvents

The Gerstel-Twister allows analysis of organic compounds from aqueous matrices by Stir Bar Sorptive Extraction (SBSE): Faster than conventional liquid/liquid extraction techniques, and omitting time/cost preparation steps and solvents and up to 1000´ more sensitive than SPME.

The GERSTEL-Twister looks like a conventional magnetic stirring rod and works the same; except for one small difference: While stirring, it adsorbs and concentrates the organic contents onto its sorbent coating. It makes no difference if the carrier solution is drinking or waste water, body fluids or beverages.

After extraction, the Twister may be washed in UHQ water to remove not truly absorbed material.

Twister faser:


PDMS Twister

EG/Silicone Twiste

PhasePolydimethylsiloxane (PDMS)Polydimethylsiloxane (PDMS) / Ethylene glycol (EG) – copolymer on an inert metal grid for mechanical stabilization

Unspecific binding of apolar compounds

log(Kow) > 4

The polarity range can be increased by adding salt

Unspecific binding of apolar compounds, additionally specific binding of polar hydrogen bond donors, e.g. phenols
Application examples

Pesticides in water

PAH in marine tissue

2,4,6-TCA in wine

Flavor compounds in food…

Flavor compounds in beverage



After extraction, Twister is transferred to the Thermal Desorption Unit TDU or to the Thermal Desorption System TDS. This means that the thermal desorption, chromatography and subsequent detection of the organic compounds adsorbed on the PDMS coating are performed directly from the Twister.


Non volatile or thermally unstable compounds can be extracted from the Twister by TwisterBackExtraxtion (TBE) and subsequently analyzed by LC or LC/MS. Also this entire process, solvent addition, wait for extraction and injection is fully automated by Maestro.


  • Up to a 1000 times lower detection limits than SPME
  • Quantitative, with large linear range
  • Several samples may be extracted at the same time
  • Time efficient

Twister Application Fields

The Twister has proved itself in many different application fields, for example essence and perfume industries, and detection of environmentally harmful substances such as polyaromatic hydrocarbons and pesticides. Due to its mechanical stability Twister may also be used for outdoor applications and is easily shipped.


  • Foods, especially beverages
  • Flavors and perfumes
  • Environmental analysis of water or waste water and air
  • Biomedicine, including body fluids
  • Quality control
  • Residue

Feel free to send us a message via the contact form and we will reply back as soon as possible.

Contact us on

Or call our main number

 +45 44 53 93 66

Contact form