EFFECTIVENESS OF INTERFERENCE FILTERS FOR REDUCTION OF STRAY LIGHT EFFECTS IN ATOMIC EMISSION SPECTROMETRY

Quantitative data are presented on the effectiveness of interference filters for reduction or elimination of stray light effects in optical spectrometers employed for trace atomic emission analyses. Specific attention is focused on those analyte species that contribute significant stray light at wavelengths far removed from the offending radiation. For simultaneous multielement determinations with a polychromator, band reflection filters are shown to provide an attractive means of eliminating stray light effects arising from the very intense Ca lines emitted in an inductively coupled plasma. For the spectrometers used in the present study, a major fraction of the background shifts caused by changing concentrations of Mg arose from real background contributions rather than from stray light.