The present invention provides an apparatus and method for producing ultra-high purity nitrogen. In accordance with the method and apparatus, air is rectified to produce a tower overhead comprising high purity nitrogen rich in light elements, such as neon, helium and hydrogen. The tower overhead is then partially condensed within a condenser and separated into liquid and vapor phases within a phase separator. The liquid phase is lean in the light elements and the vapor phase is rich in the light elements. The liquid phase is removed from the bottom of the phase separator and is introduced into the column as reflux. As the reflux drops from tray to tray it is stripped of the light elements. A product stream containing ultra-high purity nitrogen is withdrawn as a liquid from the column after suitable stripping of the reflux. The product stream can be further purified by stripping the product stream within a stripper column.