Determination of low concentration of sulphorhodamine B in wastewaters and stabilization ponds

The use of sulphorhodamine B, a known red fluorescent dye as a quantitative tracer in hydrological studies related to wastewaters has been proved experimentally. The interference in the accuracy of fluorescence readings owing to dissolved or suspended contaminants in wastewaters, especially at low concentrations of dye, was solved by successive filtering and eluting of the sample through a sep-pack C-18. The sulphorhodamine B, which is concentrated by displacement with small volumes of methanol, was thus retained. Volumes were then read with an fluorescence spectrophotometer. The procedure was demonstrated to be valid for use with sewers, stabilization ponds and wastewaters for concentrations as low as 5 × 10−7 g litre−1.