Speciation is key information to unveil the environmental behaviors of radionuclides and becomes complicated due to the presence of various components in subsurface environments that potentially interact with radionuclides and the variation of physicochemical conditions. Time-resolved laser fluorescence spectroscopy (TRLFS) is an analytic technique for the speciation of fluorescent actinide ions such as UO22+ and Cm3+ or their chemical homologues such as Eu3+. Conventional data reduction for TRLFS mainly focuses on exponential fitting of fluorescence decay at a given wavelength or deconvolution of a fluorescence spectrum measured at a given time after the irradiation of incident laser light, although TRLFS data itself is inherently multi-dimensional. This loss of information can be circumvented by the use of multi-mode factor analysis. In this study, we will demonstrate the applicability of parallel factor analysis (PARAFAC), a multi-mode factor analysis method, for TRLFS 1. The data analyzed is a collection of TRLFS data as a function of chemical variables such as pH and therefore is defined by three coordinates (wavelength, time, and a chemical variable). The multi-dimensionality of the analysis makes the application robust and allows one to simultaneously obtain the information necessary for the speciation of a target ion, that is, the number of factors and their spectra, decays, and intensity profiles as function of the chemical variable. The sorption of Eu3+ and UO22+ on minerals as well as their complexation with inorganic ligands and natural organic materials have been studied in detail in our group and will be presented in the meeting.1. Saito, T.; Sao, H.; Ishida, K.; Aoyagi, N.; Kimura, T.; Nagasaki, S.; Tanaka, S., Environ. Sci. Technol. 2010 , 44, 5055-5060.

Application of multi-mode factor analysis for time-resolved laser fluorescence spectroscopy to study radionuclide interaction with minerals and natural organic materials

248th National Meeting (2014)

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