Compact Teflon still for sub-boiling distillation of acids

Abstract

A compact distillation set-up has been developed for the ultra-purification of acids needed for trace analysis. The distillation vessel consists essentially of a double-walled Teflon beaker covered with a fluorinated ethylene propylene (FEP) Teflon window, which allows radiation from an infrared heat lamp to be admitted. The distilled acids condense on the cooled outer wall and are collected through an outlet in the bottom of the vessel between the two walls. Although the set-up was initially designed for purifying hydrofluoric acid, it has also proved to be useful for the purification of other acids, viz., hydrobromic and nitric acid.