ATOMIC EMISSION GAS-CHROMATOGRAPHIC DETECTION - CHEMICAL AND SPECTRAL INTERFERENCES IN THE STABILIZED CAPACITIVE PLASMA (SCP)

The stabilized capacitive plasma (SCP) is a 27 MHz discharge in helium at atmospheric pressure used as atomic emission source for element specific detection (ESD) in gas chromatography. The discharge is sustained in a liquid-cooled fused-silica tube surrounded by two annular electrodes. The introduction of small amounts of various gases (H-2, O2, N2, CO2, Ar) into the helium plasma leads to significant changes in the spectral emission pattern and the emission intensity of important analyte lines. The analytes were introduced into the plasma at constant flow using a diffusion device and by chromatographic separation of test mixtures. Both a monochromator and a polychromator system were used to detect spectral emission in the near-infrared region.