Evaluation of a radio frequency plasma for oxygen‐selective detection in capillary gas chromatography

Abstract

SummaryA radio frequency plasma detector for capillary GC has been modified for oxygen-selective detection. Purification of the plasma gas and purging of both ends of the discharge region with helium were crucial to minimizing oxygen background emission from impurities in the plasma. With a pure helium plasma, eluting hydrocarbons released oxygen from the discharge region resulting in interfering signals on the oxygen channel. These interfering signals were efficiently reduced by using a methane-doped (0.15%) low power RF plasma (15 W) sustained in a high make-up flow (150 mL/min). With this plasma, a i03:i oxygen-to-carbon selectivity and a 100 pg oxygen/s detection limit were obtained.The detector was linear over three orders of magnitude.The detection system has been used to screen for oxygenated compounds in two environmental samples.

Determination of Extractable Organic Chlorine and Bromine by Probe Injection Dual-Microplasma Atomic Emission Spectrometry

“…The optical part of the system has been described in detail elsewhere in connection with gas chromatographic detection. − The analytical plasma was viewed side-on through the wall of the silica tube. Atomic emission was measured in the near-infrared part of the spectrum by a Model H-20 IR monochromator (Instruments SA, Metuchen, NJ) equipped with 500 μm slits.…”

“…Therefore, in the present work, a 350 kHz helium plasma was utilized due to the straightforward energy coupling and because of the excellent analytical properties, as demonstrated for gas chromatographic detection. [24][25][26][27][28][29][30][31][32][33][34][35][36][37] To enhance the sensitivity of the method, the extraction solvent was evaporated prior to analysis. The solid sample was subsequently introduced at the plasma inlet by a sample probe.…”

“…Microwaves have frequently been applied to sustain small helium plasmas, but the energy coupling is relatively complicated and requires the use of special cavities. Therefore, in the present work, a 350 kHz helium plasma was utilized due to the straightforward energy coupling and because of the excellent analytical properties, as demonstrated for gas chromatographic detection. − To enhance the sensitivity of the method, the extraction solvent was evaporated prior to analysis. The solid sample was subsequently introduced at the plasma inlet by a sample probe.…”