5. Presentation of conventional media

The choice of adsorbent depends on the volume to be preconcentrated to achieve the required detection limits, and the nature of the solutes to be extracted. For this reason, a sound knowledge of solute retention mechanisms on the stationary phases used in LC, and therefore close to those used in SPE, enables a judicious choice of adsorbent and of the preconcentration protocol to be implemented. This knowledge will also enable us to deduce the most favorable elution conditions for solutes.

For the analysis of aqueous samples, the adsorbents used are those employed in reverse phase polarity partition chromatography, since water is then the least eluting solvent, which is favorable to solute retention. On the other hand, for the analysis of organic samples (petroleum, oils, etc.) or the purification of extracts from solid matrices contained in organic solvents, polar...