HPLC columns

Reverse phase HPLC

• mobile phase: polar liquid
  (often a mixture of water with either methanol, ethanol, acetonitrile, or tetrahydrofuran)
• stationary phase: nonpolar sorbent
  (often C18-phase immobilized on carrier)
  
• most commonly used HPLC technique in environmental trace analysis of organic pollutants

Normal phase HPLC

• mobile phase:
  apolar liquid
  
• stationary phase: polar sorbent

stainless steal cylinders (length: up to 25 cm; inner diameter: mm-size)