Magnetic stir bar Twicester®

The GERSTEL Twicester® offers a simple possibility to position one or more Twisters magnetically on the inner wall of a sample vial for more efficient sample extraction. The Twicester approach enables the extraction of a sample using more Twisters simultaneously, for example using Twisters with different types of phases for a more complete combined extraction and improved analyte recovery. The method, referred to as Multi-Stir Bar Sorptive Extraction (mSBSE), was developed in a cooperation between GERSTEL K.K., Tokyo, Japan, and the Research Institute for Chromatography (RIC) of Professor Pat Sandra in Kortrijk, Belgium. Twicester is well suited for the simple and efficient determination of a wide range of flavor compounds in aqueous matrices and it has been used successfully for the analysis of beverages. A key element of the method is the use of both PDMS- and EG-Silicone Twisters in one vial and the simultaneous desorption of both Twisters combined into a single GC/MS run. While the PDMS Twister stirs the sample extracting non-polar to medium polarity compounds, the EG-Silicone Twister is held in position on the inside wall of the vial by the Twicester clip. The EG-Silicone Twister very efficiently extracts more polar compounds that form hydrogen bonds as hydrogen donors, for example phenols. Twicester can be used to place Twisters in the liquid phase or in the headspace as required. mSBSE using the GERSTEL Twicester® enables the determination of compounds over a wide polarity range in just one step.