Reduction of Spectral Interferences in Flame Emission Spectrometry by Selective Spectral-Line Modulation

摘要

Spectral interferences in flame emission spectrometry have been significantly reduced through the use of selective spectral-line modulation (SLM). In this method, a mirrored, rotating chopper is used to direct the emission from a sample flame alternately through and around a second (modulating) flame; selective modulation is achieved when the modulating flame contains absorbing atoms identical to emitting analyte atoms in the sample flame. In this paper, the effect of optical configuration and modulating conditions on working curve slope, linearity and signal-to-noise ratio is examined. Also, the ability of SLM to minimize broad-band and narrow-line spectral interferences is demonstrated. In particular, it has been shown that the interference of the 550 nm CaOH band on barium determinations can be largely overcome. Also, interference of several Pd lines on Ni in the 350 nm region can be reduced by SLM. Finally, it is shown how the interference of flame background itself can be restricted in SLM procedures. (Author)