INSTRUMENT-INDUCED EFFECTS IN THE ANALYSIS OF POLYCYCLIC AROMATIC-COMPOUNDS BY CAPILLARY GAS-CHROMATOGRAPHY WITH ATOMIC-EMISSION DETECTION (GC-AED)

Peak splitting of high molecular weight polycyclic aromatic compounds originating from the microwave plasma of an atomic emission detector ( AED) coupled to a GC has been described and evaluated. The influence o f the solute structure, solute concentration, and physical conditions in the AED (such as detector temperature, make-up gas flow, concentrat ion of reagent gases and distance of column end from the plasma) have been studied. An explanation is presented for peak splitting, which is based on an insufficient solute decomposition and solute mass flow in the discharge tube. Modification of the instrument by introduction of additional make-up gas applied through the transfer line has been sho wn to improve peak shape and solute response.