Solvents, buffers, and additives commonly used in conventional LC, in which detection relies on analytes being in solution, may not be compatible with LC-MS analysis. Mass spectrometric detection relies on desolvation to produce gas phase analyte ions with complete removal of other eluent components. An efficient process will result in optimized analyte response and increased sensitivity. In this module we will examine common additives used in LC-MS and explain the role of solvents, buffers and eluent pH in signal optimization.

Topics include:

• LC-API compatibility
• ESI solution chemistry
• ESI eluent solvent
• Solvent viscosity in ESI
• Organic modifiers in ESI
• Eluent solvent - positive ESI
• Eluent pH - positive ESI
• Eluent pH - negative ESI
• ESI positive/negative ion mode
• ESI reagents for pH control
• Sources for non-volatile systems
• Z-spray and non-volatile systems
• ESI test compound infusion
• ESI buffer choice and concentration
• Eluent buffer ion suppression
• ESI ion pair reagents
• Cationization vs. anionization in ESI
• Pre- and post-column addition in ESI
• Post-column addition in ESI
• ESI adduct formation
• ESI considerations
• APCI solvent choice - overview
• APCI solvent choice - mechanisms
• Buffers for APCI - overview
• Buffers for APCI - concentration
• Ion pairing reagents in APCI
• APCI considerations