Application of Atomic Fluorescence Spectrometry to the Determination of Sulfide Ion in Sewage Waters

Atomic fluorescence spectrometry and direct flame photometry are evaluated as alternative methods for the determination of inorganic sulfide in municipal sewage. The sulfide is volatilized as H₂S from the sewage influent or effluent sample, which has been stabilized by a 0.05 M sodium ascorbate buffer. Both flame spectrometric methods are more sensitive than the standard colorimetric method, but quantification is easier for the atomic fluorescence method. The latter technique has a wide linear dynamic range and is unaffected by a gradual increase in the residual H₂S level in the system. The atomic fluorescence signal is also unaffected by the presence of volatile hydrocarbons in the sewage. The results obtained with the fluorescence method agree well with those obtained with the standard method, while the flame photometric results are low. Studies on the effect of metal ions on the fluorescence signal indicate that the method determines “total sulfide”.