Problems caused by the activity of Al2O3-PLOT columns in the capillary gas chromatographic analysis of volatile organic compounds

Al2O3-PLOT columns are used with great advantage for the analysis of volatiles, because of the increased capacity ratio and selectivity compared to WCOT-columns. Their applicability is limited to relatively non-polar components with relatively low boiling points i. e. eluting before n-decane. In the analysis of the halocarbons in stratospheric air, the decomposition of certain compounds was observed. In this study the stability of a number of volatile organic compounds was determined in function dependence of the column temperature using a two-dimensional GC-system. A possible reaction mechanism for the decomposition is proposed and confirmed for several chlorinated ethanes.