Potential of Radio Frequency Glow Discharge Optical Emission Spectrometry for the Analysis of Gaseous Samples

The analytical potential of a radiofrequency glow discharge (rf-GD) for the analysis of gaseous samples is evaluated investigating the detection by optical emission spectrometry (OES) of nonmetals in organic vapors using helium as plasma gas. Discrete amounts of low boiling point organic liquids are introduced into the rf-GD through a thermoelectrically heated gas exponential dilutor, and their OES characteristics are measured. The design of the discharge chamber and the effect of operating parameters on the emission signals of typical nonmetallic elements are discussed. Analytical performance is evaluated under the optimum conditions for Cl, C, Br, and S using emission lines in the ultraviolet−visible region. Detection limits in the low picogram-per-second range, good precision (RSD < 5%), and linear ranges of 4−5 decades were observed for the four elements. A comparison of this source is carried out with other, more conventional plasmas for the determination of low levels of nonmetals in organic compoun...