The relationship between micellar sensitization and the structure of the organic chromogenic reagent was studied. The sensitivity of Cd(II)-Cadion 2B was higher than Cd(II)-Cadion without any surfactants. But the sensitivity of Cd(II)-Cadion was enhanced more pronouncedly than that of Cd(II)-Cadion 2B with addition of surfactants. The enhancement by surfactants had such sequence: SDBS > mixed surfactants > SDS > cationic surfactants. Take Triton X-100 as an example, the effective dielec. constants and distribution coefficients of Cadion, Cd(II)-Cadion, Cadion 2B, Cd(II)-Cadion 2B in micellar solution were determine The location and orientation of the solubilizers in the micelles were studied also by means of micelle-sepn. method and spectrophotometry. The structure of Cd(II)-Cadion and Cd(II)-Cadion 2B were investigated. Some conclusions were drawn from these results: It was confirmed that the amphiphilic structure of the reagent and its complex played an important role in the micellar sensitizing effect. The solubilizer had pronounced amphiphilic structure causing solubilized species into the palisade layer of micelle. The cross area section and the amphiphilic structure of the solubilizer determine the sensitizing effect. In such situation the enriching effect of the micelles and the "rigid unsym. microenvironment" effect might take place. The above results were discussed based on the structures of Cd(II)-Cadion and Cd(II)-Cadion 2B.

Key words: SPECTROPHOTOMETRY, MICELLE, SURFACTANTS, COLOUR REAGENTS, MOLECULAR STRUCTURE, NITROBENZENE P, AZO COMPOUNDS, BENZENEDIAZONIUM P, CORELATIONS, SENSITIZING