In-column pyrolysis: A new approach to an old problem

High-molecular-weight fragments produced during pyrolysis of both natural a nd synthetic materials often carry the most significant structural. informa tion. Their diagnostic value is usually limited when using commercial pyrol ysis devices because of analyte discrimination on transfer from the pyrolys is unit to the GC column, A. device enabling pyrolysis in line with GC colu mn was developed to overcome this problem. Pyrolysis is carried out in a se gment of deactivated stainless steel tubing. One and of the tubing is conne cted through a restrictor to a standard GC injector, and the other end is c onnected to a precolumn followed by a GC column. Pyrolysis is carried out b y passing a pulse of electric current from a capacitive discharge power sup ply through the tubing. Nondiscriminated alkane pattern up to C-58 (limited by the temperature limit of the GC stationary phase) was observed for the pyrolysis of polyethylene. A comparison of conventional pyrolysis with in-c olumn pyrolysis indicates that the range of semivolatile pyrolysis products that can be detected in the pyrograms extends much further toward higher-b oiling compounds for the technique proposed. The new approach has also prov ed very useful in methodical variations of pyrolysis, including thermochemo lysis using tetramethylammonium hydroxide.