Self-assembly of cellulose nanoparticles as electrolyte additive for capillary electrophoresis separation

• Octadecyl modified quaternized cellulose (ODMQC) was successfully synthesized.
• ODMQC could self-assemble to form stable nanoparticles in aqueous solution.
• ODMQC coating could generate anodal eletroosmotic flow over a broad pH range.
• ODMQC did not only favor the separation of charged solutes but also neutral solutes.

In this work, a new cellulose derivative, octadecyl modified quaternized cellulose (ODMQC), was synthesized and used as additive in the background electrolyte for capillary electrophoresis. The derivative bearing hydrophobic groups and hydrophilic groups can self-assemble into a stable nano-scaled micelle structure in aqueous solution. When ODMQC was added in running buffer, the capillaries were shown to generate applicable anodal EOF over the investigated range of pH 3.0–12.0. Due to the lack of UV active groups, the ODMQC did not disturb the UV detection. It is shown that ODMQC-added capillaries allow the separation of basic proteins by reducing their adsorption onto the capillary wall. Also, the addition of ODMQC provides adequate separation of aromatic acids with low pKa values and improved separation of sulfa drugs. Moreover, it is demonstrated that the addition of ODMQC can incorporate an additional reversed-phase mechanism that improves the separation of neutral analytes.