Time-resolved laser-induced fluorescence spectroscopy combined with parallel factor analysis: a robust speciation technique for UO2 2+

Time-resolved laser-induced fluorescence spectroscopy (TRLFS) is a powerful speciation technique for fluorescent metal ions and can be further improved by combining with multi-mode factor analysis such as parallel factor analysis (PARAFAC). This study demonstrates the applicability of TRLFS combined with PARAFAC for the speciation of uranyl (UO2 (2+)) in the presence of silicic acid (Si(OH)(4)). A series of TRLFS data with varied Si(OH)(4) concentration was processed by PARAFAC, resulting in three factors corresponding to free UO2 (2+), UO2SiO(OH) (3) (+) , and UO2OH+. The stability constant of UO2SiO(OH) (3) (+) was further optimized, based on the intensity profiles of the factors.