A fluorimetric method for the determination of chlorine and tetrachloroethene by bleaching of rhodamine B

A new fluorimetric method for the determination of tetrachloroethene and chlorine is based on the irreversible bleaching of Rhodamine B, which is either immobilized in a silicone polymer, or collected on a filter from an aerosol. Tetrachloroethene is decomposed to produce small amounts of chlorine, which reduces the fluorescence of Rhodamine B. With the immobilized Rhodamine B the detection limits were 2.1 mg/m¹ for chlorine in air, and for C₂Cl₄ 3.5 mg/m³ and 2.3 mg/l. in the gas and liquid phase respectively. A Rhodamine B aerosol was used as a trace catcher. This aerosol was mixed with the trace gas, irradiated, and collected on a membrane filter and its fluorescence intensity was measured. The detection limits by this approach were estimated to be 6 μg/m³ for Cl₂ and 55 μg/m³ for C₂Cl₄.