Abstract:

The fluorescent reactions of lanthanum, yttrium with oxine-5-sulfonic acid(H2QS) in the presence of cationic surfactant-cetyltrimethylammonium bromide (CTMAB) were studied. The sensitizing mechanism of CTMAB on the fluorescent reactions was discussed based on absorptivities and quantum efficiencies of the fluorescent complexes. The fluorimetric method for determination of La, Y was developed. The ternary complexes showed the maximum excitation wavelength at 393 nm, the maximum emission wavelength at 505 nm. In comparing with their binary complexes, the fluorescence intensity of the ternary complex increased by 4-fold in the case of La and 10-fold in Y. 2 ppb Y and 20 ppb La in the solution can be determined. The presence of surfactant also increases the selectivity of the reaction. Y can be determined satisfactorily, even if there is 500-fold excess of La. Based on this principle, the determination of La and Y in the rare earths was designed, by which Y was first determinedand then with a simple graphic method La was determined. Three mixed samples with different known content of rare earth elements were determined for Y and La, the coefficients of variation were less than 10%. Our experiment showed this method was simple and the results were satisfactory without any separation.