The purpose of this module is to highlight the various steps in the protocol for various modes (sorbents) for conventional solid phase extraction procedures including: non-polar SPE, polar SPE, cation exchange SPE, anion exchange SPE, and mixed-mode SPE. For each mode the various portocol steps are examined in terms of the solvents and solutions used, sorbents used, solvent additives, pH, and ionic strength manipulation.

At the end of this unit you will be able to identify the correct SPE mode to optimize the selectivity of the procedure for the analyte of interest, choose the correct sorbent for various modes of SPE, optimize analyte retention through correct sorbent equilibration, conditioning, and sample loading by controlling sorbent activity, sample and sorbent ionic strength analyte and sorbent degree of ionization, maximize extract cleanliness by optimizing the wash solution solvent strength and ionic strength and pH where appropriate, and maximize analyte recovery and selectivity by optimizing the elution solvent and ionic strength and pH where appropriate.

Topics include: 

• Non-polar SPE
• Non-polar SPE sample pre-treatment
• Non-polar equilibration and sample loading
• Non-polar sorbent washing and analyte elution
• Polar SPE
• Polar sample pre-treatment
• Polar sorbent conditioning, equilibration, and sample loading
• Polar sorbent washing and analyte elution
• Cation exchange SPE
• Cation exchange SPE sorbents
• Cation exchange sample pre-treatment
• Cation exchange sorbent conditioning, equilibration, and sample loading
• Cation exchange washing and analyte elution
• Anion exchange SPE
• Anion exchange SPE sorbents
• Anion exchange sample pre-treatment
• Anion exchange sorbent conditioning, equilibration, and sample loading
• Anion exchange washing and analyte elution
• Minimum pKa differential
• Mixed-mode SPE
• Mixed-mode SPE sorbents
• Mixed-mode sample pre-treatment
• Mixed-mode sorbent conditioning, equilibration, and sample loading
• Mixed-mode washing analyte elution
• Mixed-mode summary