Van de Graaff generator for capillary electrophoresis

A new approach for high voltage capillary electrophoresis (CE) is proposed, which replaces the standard high voltage power supply with a Van de Graaff generator, a low current power source. Because the Van de Graaff generator is a current-limited source (10 μA), potentials exceeding 100 kV can be generated for CE when the electrical resistance of the capillary is maximized. This was achieved by decreasing the capillary diameter and reducing the buffer ionic strength. Using 2 mM borate buffer and a 5 μm i.d. capillary, fluorescently labeled amino acids were separated with efficiencies up to 3.5 million plates; a 5.7 fold improvement in separation efficiency compared to a normal power supply (NPS) typically used in CE. This separation efficiency was realized using a simple set-up without significant Joule heating, making the Van de Graaff generator a promising alternative for applying the high potentials required for enhancing resolution in the separation and analysis of highly complex samples, for example mixtures of glycans.