Optimization of solid phase extraction chromatography for the separation of Np from U and Pu using experimental design tools in complex matrices

Abstract

Effective solid phase extraction separation methods of actinides and fission products are required in the control and evaluation of common or experimental nuclear spent fuel reprocessing strategies and environmental contaminated samples. In this study, we have developed a simpler sequential analytical separation scheme to isolate ²³⁷Np from U and Pu. Experimental design tools were used to achieve parameter optimization. We studied the contribution of critical factors such as the type of resin, acidity, sulfamic acid concentration and sample volume to actinide extraction with a multivariate approach. Following a sequential assembly approach, fractional factorial designs were used to select the best resin. Full factorial designs were used to evaluate the expected response for the chosen multifactorial space. After discarding a first order linear model, the designs were augmented and the response surface methodology was used to evaluate the response through the use of a quadratic model together with graphical and canonical analysis. Knowledge acquired from multiple actinide responses allowed us to find multi-criteria compromise solutions that were successfully applied for the separation of Np from Pu and U in complex matrices.