Symmetrical (double-speed) static coating for high-resolution gas chromatography column preparation

“Breakthrough” during static coating could be avoided using a new coating strategy: while filling the capillary support with coating solution, a short mercury plug was placed at the middle of the support length. Mercury was frozen by a cold source and vacuum was applied to both open ends. In this way static coating became symmetric and so evaporation rate was doubled, on a time base, and more than doubled on a coated length base. Coating time at room temperature varied from ∼20 min for 3-m columns to ∼3 h for 15-m columns.