Three Reasons To Use Solid-Phase Extraction (SPE)
1. You need to remove specific interferences from your sample so that they do not cause problems for the detection and quantitation of analytes of interest. In the example shown here, an inadequate sample preparation protocol failed to remove interferences, as seen by the residual yellow color of the extract and many peaks overlapping the analytes of interest in the chromatogram.
2. You need to increase the concentration of the analyte of interest in the original sample so that it can be more readily detected and more accurately quantitated by your analytical technique. A large sample volume may be loaded onto an SPE column if the analyte of interest is strongly retained. Then the analyte may be eluted in a very small volume, thereby increasing its concentration in the sample aliquot presented to your chosen analytical tool.
3. You need to remove interferences in your sample that, though invisible, suppress the signal for the analyte of interest as detected by mass spectrometry. In the example shown here, protein precipitation failed to remove the phospholipids from a plasma extract, causing severe ion suppression. An optimized mixed-mode SPE protocol provides the cleanest extract and minimizes ion suppression.