The aim of this module is to give an overview of the mechanism of normal phase chromatography (NP-HPLC) and explain the basis of the retention mechanism. Typical NP-HPLC applications will be highlighted. Retention order in NP-HPLC is explained, and the influence of mobile phase composition on retention demonstrated. We will illustrate how the mobile phase composition and constituents might be manipulated to optimize chromatographic separations in NP-HPLC. The principles which are used to select appropriate stationary phases and column geometry are also discussed. 

At the end of this module you will be able to outline the advantages and limitations of NP-HPLC compared to RP-HPLC as well as describe the issues with water in NP-HPLC mobile phases, giving strategies to practically overcome problems. You will also be able to explain the best way to get started with NP-HPLC, and to optimize the chances of a successful separation.

Topics include: 

• Mechanism of normal phase chromatography
• Applications of normal phase chromatography
• Retention and selectivity - stationary phases 
• Stationary phases for normal phase HPLC
• Typical mobile phases
• Controlling retention
• Mobile phase optimization
• Problems with water in the mobile phase
• Getting started with normal phase HPLC