Enhancement of emission from indium in flowing liquid anode atmospheric pressure glow discharge using organic media

The effect of addition of low molecular weight organic compounds, Le. acids, salts and alcohols, on the emission measured from In with flowing liquid anode atmospheric pressure glow discharge optical emission spectrometry (FLA-APGD-OES) was studied. It was revealed that a small addition of CH3OH or C2H5OH (0.5%, v/v) enhanced the intensity of In 451.1 nm atomic line over 30-times. The observed boosting of emission was caused both not only by promotion of the analyte transport efficiency from the liquid sample to the plasma phase (increased from 19% to 35%) but also due to some other factors, presumably the improvement of atomization/excitation conditions. The developed FLA-APGD-OES method offered a very low detection limit of In which was 0.21 mu g L-1 (using a miniaturized spectrometer) or even 0.030 mu g L-1 (using a high-resolution spectrometer). Furthermore, it was demonstrated that addition of alcohols significantly reduced the matrix effects from several interfering species, e.g. Ag, Cu, Pb and Zn, and only in case of Na, the anti-interference effect was observed. The intensity improvement which resulted from the addition of alcohols, was observed for In only and it did not occur for other elements such as Ag, Cd, Hg, Pb, Tl and Zn.