16 Sep


You have the sample which you have been waiting for but it is only a few milliliters and you must clean it up before analysis.  The answer is to use solid phase extraction as part of your sample preparation.  SPE disks and columns have a solid stationary phase of polar compounds bound to silica (for reverse phase) of either C8 or C18 on a disk in the bottom of a syringe or small column.  Normal phase uses polar compounds bound to silica as the stationary phase.  Ion exchange SPE is also available.

The disks are first wetted or conditioned with appropriate solvent or buffer for the solid phase.  The disks then washed with the sample buffer.  The sample is the loaded or passed through the disk by either gravity or vacuum (columns) or pressure (syringe disks) or centrifugation (microplate disks).  The disks are then washed with a solvent which will not elute the analyte of interest so the analyte is retained on the disk.  The sample is then eluted from the disk with an appropriate solvent (non-polar for reversed phase, polar for normal phase).   It may then be necessary to evaporate the elution solvent and reconstitute your sample in an appropriate solvent or buffer for further analysis.

Robin Prymula