Off-Line Desalting of Peptide Mixtures

INTRODUCTION

Reversed-phase-trapping (desalting) cartridges are used for concentrating and desalting peptide samples before analysis by liquid chromatography–mass spectrometry (LC–MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI–MS). They provide a robust and efficient method for concentrating very dilute peptide solutions. Because large volumes of wash buffer can be used to wash away unbound salts and other contaminants, the trapping cartridges are frequently used to clean peptide samples before mass spectrometry analysis, as described in this protocol.