Characterisation of a Radiofrequency Plasma Discharge Reactor for Use in Chromatography Detection Based on Ion Mobility Spectrometry and Chemiluminescence Measurements

In the proposed project organic compounds are converted in a capacitively coupled rf discharge - under the "catalytic" action of electrons and rare gas ions - to small molecular fragments. Addition of reagent gases such as O2, N2O, CO2, N2, H2O, CH4, H2, etc. allows the combustion conditions in the rf discharge reactor to be varied from oxidising to reducing. The reactor tube wall is maintained at low temperature to minimise corrosion effects. Under appropriate conditions proton transfer and electron attachment produce positive and negative ions in the decaying plasma and the afterglow region. These ions, or stable ion-molecule reaction products, can be separated in a drift tube under the action of an electric field and measured quantitatively at a collector electrode (ion mobility spectrometry). Electrically neutral combustion products will be mixed with in-situ generated ozone or other compounds known for their ability to induce chemiluminescent reactions. The emitted radiation is monitored with spectral resolution to obtain element specific information. All these processes may occur at atmospheric pressure. The dominant constituent of the discharge exhaust gas is a monoatomic inert gas (He or Ar) and conditions are nearly ideal for quantitative determination of sample fragments. Implementation of the plasma as a flow-tube reactor with minimal dead volume allows direct interfacing to the outlet of a gas chromatograph and testing th...(this text has been cut automatically)