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How the Twister SBSE Transformed Sample Preparation for Chromatography

SBSE_Pat-Sandra.jpgIt may now be the extraction technique of choice for many sample types, but stir bar sorptive extraction (SBSE) started with a complaint. Pat Sandra, University of Ghent Professor Emeritus and founder of the Research Institute of Chromatography in Belgium, recalled that a commenter to one of his papers on analyte absorption by polydimethylsiloxane (PDMS) observed that adsorption of PCBs on a typical Teflon-coated stir bar used in the experiments interfered with the data interpretation.

Taking that as a challenge, Sandra discovered that eliminating the need for a Teflon stir bar by coating a stir bar directly with PDMS absorbed all the PCBs, leading to the invention of SBSE. The preparation technique didn’t require solvents, increased sensitivity for hydrophobic compounds, and changed how chemists prepare samples for chromatography. Professor Sandra wrote about the history of what became the Twister stir bar in a recent article in GERSTEL Solutions Worldwide.

Initially, SBSE was used for compound extraction from aqueous solutions — several methods eventually were developed to work with food, beverages, biological fluids and other matrices. While Sandra had no intention of commercializing SBSE, GERSTEL approached him with an interest in commercialization and the Twister SBSE was officially introduced. Sandra observed that SBSE has been cited in more than 1,000 papers since its 1999 invention.

Sandra said the benefits of PDMS-coated SBSE quickly became obvious:

  • It was a green preparation technique minimizing solvent use.
  • It made analyte recovery predictable, calculating recovery from log P values of hydrophobicity.
  • It allowed very low detection limits and excellent reproducibility.

Since its invention, several more in situ derivatization methods have been introduced, expanding the technique’s applications to more hydrophilic compounds and a wider variety of matrices, and reducing the cleanup steps needed. Other coatings, such as ethylene glycol-silicone (EG Silicone) are now available, allowing high-recovery extraction of specific analyte classes in beverages, biological fluids and other matrices.

SBSE symposia, which were launched in 2011 by a scientist at Veolia Water in Paris after discovering how the Twister could detect odors in drinking water, have brought together scientists from around the world to discuss sample preparation using SBSE. This year’s meeting included speakers from France, Belgium, the U.S., Japan, the Slovak and Czech republics, and Italy.

Ironically, Sandra noted that initial criticism of the Twister’s high sensitivity have turned into an advantage. As regulations worldwide have reduced the levels of allowable contaminants in food, water, and other materials (including zero tolerance of pesticides in baby foods, etc.), SBSE’s sensitivity may have become a required part of analysis of these matrices.

You can check out Dr. Sandra’s comments and more details on the evolution of the Twister technology in the article, “Stir Bar Sorptive Extraction (SBSE): Established, Useful and Quite Often Simply the Extraction Technique of Choice,” in the GERSTEL Solutions Worldwide magazine.

We also invite you to contact us for a deeper conversation about the Twister SBSE technology, and sample preparation techniques in chromatography.