Separation of transuranium elements by gas chromatography of their chlorides Recently we have shown1 the possibility of separation of chlorides of lanthanide elements by gas chromatography at relatively low temperature when using the vapours of aluminium trichloride as, a component of the carrier gas. The starting point was the work of GRUEN AND 0~~2~8 who have found that A12C1, vapours interact with solid NdCl, to form gaseous complexes containing neodymium. We have verified1 that this is the common property of lanthanide elements. By adding Al&l, vapours into the carrier gas in the chromatographic experiments we were able to synthesise the complexes at the moment of introduction of the sample of lanthanide chlorides into the column. The excess of Al,Cl, also suppresses the dissociation of the unstable complex molecules. The experiments were carried out in glass capillary columns (2.5 m x I mm I.D.) at 250' by the method of gas-solid chromatography. In this case the vapours of aluminium trichloride also serve to modify dynamically the surface of the glass&vb. Were we report experiments on the separation of the transuranium elements by an analogous technique. We also investigated the behaviour of protactinium and uranium. Use was made of isotopes 281l?a, 2aVJ, 237Np, 2aDPu, HiAm and za4Cm in amounts not in excess of 1 pg. The details of the experimental procedure were described in the previous reportl. In the present work we used a longer column (IO m x I mm I.D.). It should be noted that the chromatogram was measured by collecting fractions of the Al&I, condensate at the exit of the column and by measuring their radioactivity. For the identification of the alpha active elements a fraction was dissolved in hydrochloric acid, about