PDMS-Overcoating of SPME Fibers enabling improved Extractions from complex Food Samples

Klaus Buckendahl, Merck/Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany (klaus.buckendahl@merckgroup.com)
Katherine Stenerson, Milliporesigma, Bellefonte Pa, Usa
Robert Shirey, Milliporesigma, Bellefonte Pa, Usa
Yong Chen, Milliporesigma, Bellefonte Pa, Usa
Leonard Sidisky, Milliporesigma, Bellefonte Pa, Usa

Solid Phase Micro Extraction (SPME), invented by Janusz Pawliszyn in 1991 [1], has become an important technology for sample preparation in different application areas. However, for complex samples containing e.g. sugars or proteins, SPME was not ideal, in particular when using adsorbent (particle) fibers. These adsorb also matrix components too strongly, which are decomposed in the GC injector degrading the fiber and contaminating the injector. A recently developed SPME fiber technology, applying an overcoating layer of PDMS polymer over the traditional adsorbent fiber coating, can circumvent this issues.

The primary advantage of adsorbent (particle) based fiber coatings is, that the porous materials retain analytes stronger than absorbent type fiber coatings (also known as film fibers) due to the surface interaction in the pores of the particles, providing typically lower LODs. But this high analyte retention advantage may become a disadvantage if the fiber is immersed in a sample with complex matrix. The properties of adsorbent coatings that retain analytes tightly also may tightly retain non-volatile components from the matrix. This can result in fouling of the fiber coating and shorten the lifetime of the fiber and/or cause contamination of the GC injector port. By applying a layer of PDMS coating over the adsorbent coating, large matrix components are repelled or can easily be washed off, while the smaller analytes of interest can pass through the outer PDMS layer and will be retained by the adsorbent. This results in a longer fiber life time and more reproducibility.

This work will explain the overcoating technology and compare the lifetime of overcoated vs. conventional adsorbent fiber coatings for pesticide determination from complex matrices such as spaghetti sauce and show further application examples, demonstrating the expansion of the applicability of SPME.



[1] Arthur, C. L., Pawliszyn, J., Anal Chem, 1990, 62(19):2145


Short Biography of Presenting Author

Klaus Buckendahl, from Merck/Sigma-Aldrich Chemie GmbH Germany, is by training a chemical engineer with major in instrumental analysis. He started his career in the technical service of Supelco in Germany in 1995 focussing on chromatography products and is working today for Merck as an analytical science liaison for Western Europe, providing support to customers and internal stake holders with analytical know how and experience. Throughout the years in various positions, he was always focusing on analytical topics, also frequently giving technical seminars on topics in the area of GC, HPLC, LC/MS, SPME, SPE, Air Monitoring, and also covering food analysis subjects

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