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HPLC Columns: Column Configuration Packing Material Bonded Phases. HPLC Column Configuration. Porous frits close the ends of the column to retain the packing particles. HPLC Support Particles. Most often silica or silica gel (hydrated silicon-oxygen).
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HPLC Columns: • Column Configuration • Packing Material • Bonded Phases
HPLC Column Configuration Porous frits close the ends of the column to retain the packing particles
HPLC Support Particles Most often silica or silica gel (hydrated silicon-oxygen) Less often hydrated aluminum-oxygen polymers (alumina)
HPLC Support Particles Micropellicular Particle: Solid core Thin outer skin of stationary phase 1.5 – 2.5 μm sizes Very low surface area Fast separation, low capacity
HPLC Support Particles Porous Micro-sphere: Most common Large surface area Variety of pore sizes High capacity
HPLC Support Particles Perfusion Particle: Least common Very large pores (0.5 μm) High flow rate (fast) Macromolecules (proteins)
Particle Size Considerations H dp2 ΔP L/ dp2 N ≈ 3500 L / dp L in cm dp in μm
Particle Size Considerations Substituted benzenes
Solid Stationary Phases (Adsorption – Normal Phase) Liquid-Solid Adsorption Analyte interacts directly with Si-OH groups Silica gel is acidic Irreversible adsorption is likely Slow re-equilibration
Bonded Stationary Phases Use Si-OH reaction Rapid Equilibration No Irreversible Adsorption
Bonded Stationary Phases R group may be: polar (normal phase) non-polar (reversed phase) ionic (ion exchange)
Bonded Stationary Phases Un-reacted Si-OH groups must be shielded or end-capped
Bonded Stationary Phases 1. Histidine 2. Arginine 3. Valine
Bonded Stationary Phases Polycyclic Aromatic Hydrocarbons
Bonded Stationary Phases monomeric C-18 polymeric C-18 end-capping
Bonded Stationary Phases: R groups Cross-linked polystyrene ion-exchange resin
Bonded Stationary Phases: R groups Normal Phase R Groups
Bonded Stationary Phases: R groups Normal Phase separation of sugars using an amino bonded stationary phase and 75:25 acetonitrile:water 1. fructose 2. glucose 3. sucrose 4. maltose
Bonded Stationary Phases: R groups Normal Phase R Groups
Bonded Stationary Phases Size Exclusion Stationary phase consists of porous particles with controlled pore diameter Separation based on size (not MW) No chemical interactions involved
Bonded Stationary Phases Each Size Exclusion column has a defined range of separation