Abstract Most sample-enrichment procedures currently available rely on adsorption of the analytes of interest by a suitable adsorbent material. Although good performance can be obtained for many practical problems, in some cases the applicability of adsorptive sample preparation falls short, particularly for the enrichment of polar and/or high-molecular-weight compounds, especially in combi- nation with thermal desorption. Because of the very strong retention of adsorbent materials, undesired effects such as incomplete desorption and artifact formation are ob- served. Polar solutes are easily adsorbed but readily un- dergo surface-catalyzed reactions and on desorption yield compounds different than those originally sampled. High- molecular-weight compounds cannot be desorbed because of extremely strong interactions with the adsorbent and their low volatility. To overcome some of these problems sample-prepara- tion techniques based on polydimethylsiloxane sorption have been developed over the past 15 years. In contrast with adsorptive trapping, sorption is based on dissolution of the analytes in a liquid polymeric material. This is a much more inert means of solute retention which overcomes some of the limitations encountered when working with adsorbents. In this contribution, the basic principles of sorption, the different instrumentation used, and applica- tions of the technique will be reviewed. The review cov- ers the sorptive sample-preparation techniques, open-tubu- lar trapping (OTT), solid-phase microextraction (SPME), gum-phase extraction (GPE), equilibrium gum-phase ex- traction (EGPE), and stir-bar-sorptive extraction (SBSE). Because of the nature of sorptive sample-preparation tech- niques, which perform particularly well in combination with thermal desorption, this review focuses strongly on gas chromatography as the means of chemical analysis. Keywords Sorptive sample preparation · Gas chromatography · Thermal desorption · Polydimethylsiloxane Introduction Most of the sample-preparation techniques currently avail- able rely on trapping of the analytes of interest from the sample (gas, liquid, or solid) by an adsorbent material; this is followed by desorption and (chromatographic) analysis. Adsorbents are porous materials with a high internal sur- face area (typically 5–1000 m 2 g –1 ) and the analytes are temporarily stored on the adsorbent surface. After analyte trapping and matrix removal the trapped analytes can be released by extraction with a small amount (typically mil- liliters) of an organic solvent. An aliquot (typically mi- crolitres) of this extract is subsequently injected into the analytical instrument. Although this approach works quite successfully, it is likely to result in poor sensitivity be- cause only a fraction of the sample is used. Overcoming this sensitivity limitation is the topic of much research into sample-preparation. Possible solutions include on- line combination of extraction with liquid chromatogra- phy and injection of large volumes into the analytical sys- tem (i.e. large-volume injection in gas chromatography). As an alternative to liquid desorption, thermal desorp- tion under an inert gas stream is increasingly being used. Thermal desorption can be coupled rather conveniently to a gas chromatograph and the (heated) carrier gas is used for thermal desorption. When cryogenic focusing is em- ployed, quantitative transfer of the analytes trapped on the adsorbent material to the chromatographic column is pos- sible; this results in a considerable increase in sensitivity compared with liquid desorption. Consequently, thermal E. Baltussen · C. A. Cramers · P. J. F. Sandra Sorptive sample preparation – a review Anal Bioanal Chem (2002) 373 : 3–22 DOI 10.1007/s00216-002-1266-2 Received: 21 November 2001 / Revised: 15 February 2002 / Accepted: 20 February 2002 / Published online: 9 April 2002 SPECIAL ISSUE PAPER E. Baltussen (✉) Notox B.V., Hambakenwetering 7, 5231DD, ‘s Hertogenbosch, The Netherlands e-mail: erik.baltussen@notox.nl C.A. Cramers Eindhoven University of Technology, Laboratory of Instrumental Analysis, P.O. Box 513, 5600 MB Eindhoven, The Netherlands P.J.F. Sandra Research Institute for Chromatography, Kennedypark 20, B-8500, Kortrijk, Belgium © Springer-Verlag 2002