Signal-to-Noise Ratio Comparison for Dispersive and Non-Dispersive Flame Atomic Fluorescence Measurements

Signal-to-noise ratios achievable with dispersive and nondispersive atomic fluorescence systems are compared. In this comparison particular attention has been devoted to considerations affecting optimization of the dispersive system with low and high background flames. Relative signal and noise values are reported for Hg and Fe atomic fluorescence with dispersive, solar-blind nondispersive, and filter nondispersive systems with C 2 H 2 -air, separated C 2 H 2 -air, H 2 -air, and H 2 -O 2 -Ar flames. It is concluded that, when due consideration is given to optimization of the dispersive system for atomic fluorescence measurements, use of a nondispersive system will not generally provide an improvement in the measurement signal-to-noise ratio and may result in a decreased signal-to-noise ratio with an atomizer of even moderate background emission, such as the separated C 2 H 2 -air flame.