Chapter 6: On-line Protein Digestion in Combination with Chromatographic Separation and Mass Spectrometric Detection

On-line digestion coupled prior to or after an analytical separation in combination with electrospray ionization mass spectrometric detection offers many possibilities to analyse proteins by means of peptides and can result in selective, efficient, fast and accurate analytical information. However, compatibility issues need to be kept in mind when directly coupling biochemical reactions with chemical separation and detection principles. This chapter deals with different modes of on-line digestion. In-solution digestion can be used in a similar way to the automated approach frequently used in immobilized enzyme reactors, but without the need to immobilize enzymes.