Chiral separations using polymeric surfactants and polyelectrolyte multilayers in open-tubular capillary...

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Polyelectrolyte multilayer (PEM) coatings on fused-silica capillaries are known for stability in achiral separations.
• Adapting PEM coatings for chiral separations requires significant procedural modifications.

Purpose of the Study:

• To develop and optimize a PEM coating procedure for chiral separations using open-tubular capillary electrochromatography.
• To evaluate the reproducibility and stability of the optimized PEM coatings for chiral compound analysis.

Main Methods:

• Constructed in situ PEM coatings using poly(diallyldimethylammonium chloride) and poly(sodium N-undecanoyl-l-leucylvalinate).
• Optimized deposition parameters including additives, salt concentration, temperature, and bilayer number.
• Assessed reproducibility using relative standard deviation (RSD) of electroosmotic flow (EOF) and a specific chiral analyte.

Main Results:

• Achieved excellent run-to-run and capillary-to-capillary RSD values (<0.5% for EOF, <1% for (R)-(+)-BNP).
• Demonstrated high stability with over 230 runs on a single capillary.
• Successfully applied the modified PEM coating to separate various chiral compounds, including BNP derivatives and barbiturates.

Conclusions:

• Modified PEM coatings are effective for robust and reproducible chiral separations in capillary electrochromatography.
• Optimization of deposition parameters is crucial for successful chiral separation applications.
• The developed method offers a stable and reliable platform for enantiomeric analysis.