Explain the difference between normal-phase and reversed-phase chromatography.

Explain the difference between normal-phase and reversed-phase chromatography.

• A. Normal-phase uses polar stationary phase (e.g., silica) with nonpolar mobile phase; reversed-phase uses nonpolar stationary phase (e.g., C18) with polar (water-containing) mobile phase.
• B. Normal-phase uses nonpolar stationary phase with polar mobile phase; reversed-phase uses polar stationary phase with nonpolar mobile phase.
• C. Both use the same stationary phase; differences are in detector type.
• D. Normal-phase is used for ionizable compounds; reversed-phase for nonpolar compounds.

Answer: (A)