Nitrogen isotope separation with displacement chromatography using cryptand polymer

Chromatographic nitrogen isotope separation was experimentally studied in a break through manner. A solution of 0.4 mol.dm(-3) NH4Cl in methanol was continuously fed at 0.12, 0.25 and 0.50 cm(3).min(-1) into a glass tube packed with cryptand(2(B),2,1) polymer. The temperature of column was kept constant at 293 K by passing temperature-controlled water through a jacket. Nitrogen gas was generated from the effluent reacted with Ca(ClO)(2) solution after removing methanol by vacuum distillation, and the ratio of N-14 N-15 to (NN)-N-14-N-14 was measured with a mass spectrometer (Finnigan MAT252). NH4Cl concentrations in the samples were gravimetrically determined. An enrichment factor, which is defined as an equilibrium separation factor minus unity was determined to be 0.0025 +/- 0.0013. A HETP (height equivalent to a theoretical plate) was evaluated 0.5 +/- 0.2 cm at 14 cm.h(-1). This is the first report on nitrogen isotope separation with cryptand polymer.