Background electrolyte additive

Ionic liquids as background electrolyte additives in capillary electrophoresis... 

Library of Cyclic Oligopeptides as Additives to Background Electrolyte for Chiral Capillary Electrophoresis... 

Enantioresolution in capillary electrophoresis (CE) is typically achieved with the help of chiral additives dissolved in the background electrolyte. A number of low as well as high molecular weight compounds such as proteins, antibiotics, crown ethers, and cyclodextrins have already been tested and optimized. Since the mechanism of retention and resolution remains ambiguous, the selection of an additive best suited for the specific separation relies on the one-at-a-time testing of each individual compound, a tedious process at best. Obviously, the use of a mixed library of chiral additives combined with an efficient deconvolution strategy has the potential to accelerate this selection. 

Fig. 7. Separation of R- and S-propranolol using MIP particles as chiral additive in the background electrolyte, MIP prepared using S-propranolol as template. Reprinted with permission from Walshe M, Garcia E, Howarth J, Smyth MR, Kelly MT (1997) Anal Commun 34 119. Copyright 1997 The Royal Society of Chemistry...

Increase selectivity by increasing the difference in mobilities. This can be achieved by using appropriate electrolyte systems and other additives in the background electrolyte (e.g., complexing agents). 

Create conditions where the diffusion coefficients of the compounds are low. Typically, larger compounds have slower diffusion coefficients therefore, formation of molecular complexes is an interesting tool to enhance separation in CE. In addition, the viscosity of the background electrolyte may be increased also to reduce diffusion effects. Another parameter that may be helpful too is lowering the temperature of the separation. 

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