Date of Award


Document Type


Degree Name

Master of Science (M.S.)



First Advisor

Silvio Rodriguez

First Committee Member

Kishori Chaubal

Second Committee Member

Patrick Jones


The present study involves the determination of traces of thallium and mercury in aqueous solution by forming ion-association complexes of these metals with rhodamine 6G (R6G) in the presence of iodide. Thallium(lll) and mercury(Il) are able to quench the fluorescence of R6G in the presence of iodide by forming ion—association complexes, and the degree of quenching correlates with the thallium(III) or mercury(II) concentrations . By using this method, the minimum amount of thallium- (III) that can be determined in aqueous solutions is approximately 4.00 X 10-6m, while the minimum amount of mercury(II) is approximately 3.00 X 10-6m. Thallium(I) cannot be determined by this method because it is not possible to form ion-association complexes under similar experimental conditions therefore, this method can be used to differentiate between Tl(I) and Tl(III) in aqueous solution. To elucidate the composition of the ion-association complexes in aqueous solutions two spectrophotometric methods are used: the mole-ratio method and the continuous- variation method. The experimental results seem to indicate that two complexes are formed for the mercury(II)-R6G-iodide system. The empirical compositions of these complexes are tentatively determined to be [(R6G)HgI3] and [(R6G)2HgI4).



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