A simple radiofrequency helium discharge plasma (RFP) for spectroscopic purposes

Abstract

In this work a radiofrequency powered helium discharge plasma (RFP) for optical or mass spectrometry purposes was developed and investigated. Research focussed on the spectroscopic properties of the RFP, and its suitability as an alternative excitation source for plasma spectroscopy was proved. Halogenated organic compounds were injected into the gas flow to detect fluorine, chlorine, bromine and iodine at their most intense spectral lines resolved from interferences. With this plasma, the detection of Cl down to 125 ng without background correction is possible. Injection of air samples causes few interferences and shows the robustness of the radiofrequency plasma against large sample volumes of up to 500 µL. A Cl selectivity against N ₂ , O ₂ (both more than 5000:1) and C (250:1) is achieved without background correction. A fluorine quantification is possible for 0.25 µg only. I and Br detection also can be achieved down to 0.25 µg without any background correction.