Development of a packed precolumn for capillary gas chromatographic analysis of amines in acidic aqueous solution

This paper describes an optimization of the analysis of amines in aqueous s olution. Direct injection of the acidic sample (HCl 0.12 N) is performed by the coupling of packed precolumn with a capillary column. The basic suppor t efficiently traps residual vapors of hydrochloric acid and water at the i njection time; the capillary chromatographic performance is maintained. The precolumn coupling with PoraPLOT Amines capillary column enables a separat ion and quantification of the lower volatile aliphatic amines (methylamine, dimethylamine, trimethylamine and ethylamine). The ammonia addition to the solution (200 ppm NH3) reduces amine adsorption in the column. The analysi s repeatability is about 5% for a 50 mu M amine mixture and 21% for the qua ntification limit of 0.5 mu M with a sensitive and specific nitrogen phosph or detector. The precolumn avoids using split injection (sensitivity increa sed). Other nitrogen compounds can be analyzed by this system: aromatic ami nes (aniline) and unsaturated nitrogen heterocycles (pyridine). This new te chnique increases the chromatographic performances in comparison with usual methods; its automation is possible. (C) 1999 IAWQ Published by Elsevier S cience Ltd. All rights reserved.