Why robust background electrolytes containing multivalent ionic species can fail in capillary zone electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science
• Electromigration Techniques

Background:

• System peaks in electromigration are induced by multivalent weak ionic species in background electrolytes.
• These peaks can negatively impact analyte separation by causing peak broadening and deformation.
• Commonly used background electrolytes, such as phosphate and phthalate buffers, may not be universally applicable due to these phenomena.

Purpose of the Study:

• To demonstrate the induction of system peaks by multivalent weak ionic species in background electrolytes.
• To investigate the interaction between analytes and system peaks, leading to electromigration dispersion.
• To provide theoretical and experimental evidence for the phenomena using phosphoric and phthalic acid-based electrolytes.

Main Methods:

• Theoretical derivation of system peak existence using SystCharts and Peak Shape Diagrams.
• Experimental confirmation of theoretical predictions.
• Systematic study of background electrolytes containing phosphoric acid and phthalic acid.

Main Results:

• System peaks are induced by multivalent weak ionic species in background electrolytes.
• Analyte interaction with system peaks results in significant electromigration dispersion, peak broadening, and loss of resolution.
• Phosphate and phthalate buffers, while often considered robust, can fail for specific analytes due to system peak interference.

Conclusions:

• Multivalent ionic species in background electrolytes are a primary cause of system peaks.
• The presence of system peaks significantly compromises the separation of analytes with similar mobilities.
• Careful selection of background electrolytes is crucial for robust and reliable electromigration-based separations, especially when using phosphate or phthalate buffers.