[Study on cucurbit[ 7] uril-mediated capillary electrophoresis]

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Capillary electrophoresis (CE) is a powerful separation technique.
• Separating neutral analytes in CE can be challenging.
• Macrocyclic molecules offer unique properties for modifying CE separations.

Purpose of the Study:

• To investigate the use of cucurbit[7]uril (CB[7]) as an additive in CE.
• To achieve the separation of neutral nitrobenzenes.
• To understand the effect of CB[7] on electroosmotic flow (EOF) and selectivity.

Main Methods:

• Capillary electrophoresis with UV detection at 254 nm.
• Use of a disodium hydrogen phosphate-hydrochloric acid buffer system.
• Addition of cucurbit[7]uril (CB[7]) at varying concentrations.
• Investigation of buffer pH effects on EOF and analyte separation.

Main Results:

• CB[7] adsorbed onto the capillary wall, reversing the EOF under acidic conditions (pH 2-6.5).
• Increased CB[7] concentration enhanced the selectivity for nitrobenzene separation.
• Optimal separation was achieved with 5 mmol/L CB[7] in a specific buffer-methanol mixture.

Conclusions:

• Cucurbit[7]uril is a promising additive for improving CE separations of neutral analytes.
• CB[7] modifies EOF and enhances selectivity, enabling successful nitrobenzene separation.
• The study provides a potential method for separating challenging neutral compounds using CE.