Solid-phase extraction (SPE) is a sample preparation technique routinely used in analytical laboratories for the extraction of analytes from a complex matrix.
This sample preparation technique enables the extraction, cleanup and concentration of analytes prior to their quantification. Solid phase extraction prevents most problems encountered with liquid-liquid extraction and improves quantitative recovery yields. This technique is rapid (most extraction in less than 30 min), easy to perform and can be automated. In addition, low amount of solvents is handled and this technique is fully adapted for the pre-treatment of complex matrices such as urine, blood, food samples, water etc…
Solid phase extraction uses the difference of affinity between an analyte and interferents, present in a liquid matrix, for a solid phase (sorbent). This affinity allows the separation of the target analyte from the interferents.
A typical solid phase extraction involves four steps :
- First, the cartridge is equilibrated or conditioned with a solvent to wet the sorbent.
- Then the loading solution containing the analyte is percolated through the solid phase. Ideally, the analyte and some impurities are retained on the sorbent.
- The sorbent is then washed to remove impurities.
- The analyte is collected during this elution step.
Importance of the phase for a high selectivity
A broad range of phases exists for SPE. Most of them are based on ionic, hydrophobic or polar interactions. Their selectivity is limited and the target analyte often co-elutes with interfering compounds.
Molecularly Imprinted Polymers are the most highly selective phases available today. This technology enables to reduce the presence of interferents during the elution step and obtain higher recoveries in chromatography analysis even at low levels.
As a pioneer and expert in the development of Molecularly Imprinted Polymers, AFFINISEP has developed AFFINIMIP® SPE, a range of selective Solid Phase Extraction sorbents using the molecular imprinting procedure for sample cleanup before analysis.