Gerstel
Gerstel specializes in providing advanced automation solutions for sample preparation and sample introduction for GC/MS (Gas Chromatography/Mass Spectrometry) and LC/MS (Liquid Chromatography/Mass Spectrometry) analysis. Gerstel have a long-standing reputation in laboratory automation since they were founded in 1967.
They offer a range of products including autosamplers, software, and various systems for dynamic headspace, thermal desorption, and more, catering to laboratories in fields such as food safety, pharmaceuticals, environmental analysis, and others.
Element Laboratory Solutions supplies a selection of Gerstel products and colleagues in Cambridge have been a trusted partner of Gerstel’s for almost 30 years, offering bespoke automation solutions for a diverse range of application areas.
Consumable products include SPME (solid phase micro-extraction) and SPME arrow fibres, thermal desorption tubes, filtration options as well as vials & caps specific to applications such as dispersive liquid-liquid extraction (DiLMME) and vacuum SPME.
Choice of SPME Fibres
Several phases are available for SPME extraction. These include standard SPME Fibers, smart SPME fibres for the newer platforms and SPME arrow. Each type of phase is colour coded and the choice of phase depends on the specific application. Information on some of fibres available is given in the table below and comprehensive guides to fibre selection are available online.
| Phase | Analyte/application types |
| Polydimethylsiloxane (PDMS) | Non-polar volatiles and semi-volatiles (variety of phase volumes available) |
| Polyacrylate (PA) | Polar semi-volatiles |
| Polydimethylsiloxane/Divinylbenzene (PDMS/DVB) | Volatiles, amines and nitro-aromatic compounds |
| Carboxen®/Polydimethylsiloxane (CAR/PDMS) | Gases and low molecular weight compounds |
| Divnylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) | Flavour compounds: volatiles and semi-volatiles and trace compound analysis |
Choice of Thermal Desorption Tubes
The Gerstel Thermal Desorption Unit (TDU) comes in 2 sizes, the TDU II or TD 3.5+ with a range of tubes to match. As well as performing direct thermal desorption or Twister™ extraction sorbent tubes can be used for offline sampling with existing protocols, or in combination with the Gerstel DHS for a fully automated sample extraction/introduction online with GC.
The range of TDU II tubes are shown in the table below
| Packing | Applications |
Tenax®TA |
Volatile and semi-volatile compounds. Has a low affinity to water and methanol |
Tenax®GR |
Composite material containing 30% graphite carbon and 70% Tenax TA. Compared to Tenax TA it has a higher retention volume for volatile compounds and is twice as dense. It has a relatively low affinity to water or methanol |
| Polydimethylsiloxane (PDMS) |
For non-polar compounds. very inert and low affinity to water or methanol |
Carbopack™B Carbopack™ X |
Multi-bed adsorbent combination of two graphitized carbon blacks used for sampling compounds in the range C4 to C12. Relatively low affinity to water and methanol, but retains more water and methanol than Tenax |
Carbopack™B Carbopack™ X Carboxen™-1000 marked with a red dot for identification |
Multi-bed adsorbent combination of two graphitized carbon black and a molecular sieve. In comparison to the CarbopackB/Carbopack X combination it allows additional sampling of smaller molecules. Range C2-C12. The marked affinity to water and methanol has to be considered during sampling. |
Carbopack™ C Carbopack™ B Carbosieve™ S-III  |
Multi-bed adsorbent combination of two graphitized carbon black and a molecular sieve. In comparison to the Carbopack™B Carbopack™ X Carboxen™-1000 combination it provides an even wider sampling range of compounds (C1 to >C12). The affinity of the Carbosieve-SIII to water and methanol is also larger than it is with Carboxen- 1000. |
Carbopack™B Carboxen™-1000  Marked with a red dot or a notch |
Multi-bed adsorbent combination of one graphitized carbon black and a molecular sieve. It has similar properties as Carbopack™B Carbopack™ X Carboxen™-1000 but each layer is longer and therefore has a higher capacity. |
Carbotrap™ B, Carbopack™ X, Shincarbon X Marked with 2 red dots for identification |
Multi-bed. Designed for GERSTEL MVM method for sampling of very high volatiles (such as acetaldehyde) The marked affinity to water and methanol has to be considered during sampling. |
Vacuum SPME speeds up and improves recovery of various analyte types by undertaking the extraction under vacuum as opposed to at atmospheric pressure. The vacuum SPME closures necessary for this technique are supplied by Extratech™ and you can read about this exciting technique in Aprils Lab Mate UK & Ireland publication or in Element application Note AS304
