UTEVA-Resin

The use of UTEVA-Resin, an extraction chromatographic resin to be described in more detail below, has also been described for robotic separations of actinides in a glove box64-66 These authors designed their process to allow columns to run dry between steps to simulate what could happen in an unattended open-column process. In addition, corrosive solvents were avoided. They reported >90% recoveries and fractions that were suitable for thermal ion mass spectrometry (TIMS) source preparation without further purification or treatment. 

Actinide Separations in Flow Systems using DP[PP] Chemistry on UTEVA-Resin... 

Briefly compares UTEVA-Resin unfavorably with TRU-Resin for actinide separations for ICP-MS ICP-MS 60... 

Actinides can be separated from matrix elements, other radionuclides, and each other using extraction-chromatographic materials such as TEVA-Resin, TRU-Resin, and UTEVA-Resin. The capacity factors for various actinides on these resins, as a function of nitric or hydrochloric acid concentrations are shown in Figures 9.11 and 9.12.30 31127 Elution peaks or collected fractions from column separations can be... 

U(VI). The long separation column—preconditioned, loaded, and washed with 3 M HN03—was credited with the apparent retention of Np(V) and Am(III) under this elution program. These authors also examined UTEVA-Resin for this actinide analysis application but concluded that TRU-Resin was to be preferred for retention of actinides from urine. 

Several groups have described the use of UTEVA-Resin separations coupled to ICP-MS for actinide analyses (see Table 9.4). UTEVA-Resin contains the extractant dipentyl pen-tylphosphonate (DP[PP]), which is also known as diamylamyl phosphonate (DAAP).31 This extractant retains actinides from nitric acid solutions as nitrato complexes, with increasing uptake as nitric acid concentrations increase (see Figure 9.11). Extraction equilibria for representative species are shown in Equations 9.6 and 9.7, where the bar above a species indicates that it is immobilized on the resin.4... 

Loading the sample in nitric acid solution, the tetravalent actinides are strongly retained along with hexavalent uranium. However, trivalent actinides like Am(III) and Pu(III) are not retained from nitric acid solutions (unlike TRU-Resin). Pu retained as Pu(IV) can be removed from the column by reducing it to Pu(III). Tetravalent actinides and U(VI) are also retained in strong hydrochloric acid solution, with retention sharply dropping off as hydrochloric acid concentrations decrease (see Figure 9.12). Th(IV) is less retained in hydrochloric acid solutions than U(VI). Actinides retained on UTEVA-Resin from nitric acid solutions can be released with diluted nitric acid or low hydrochloric acid concentrations. 

Kang et al. used a UTEVA-Resin column as part of a 10-port valve FI system coupled to ICP-MS.139 Samples were loaded in 3 M HN03 and eluted in 0.02 M HN03. This simple method was developed for the preconcentration and analysis of U in seawater. Similar procedures for the analysis of U in urine or U and Th in body fluids... 

FIGURE 9.17 Separation of actinides on UTEVA-Resin with ICP-MS detection. (Adapted from Pema, L., Betti, M., Moreno, J. M. B., and Fuoco, R., J. Anal. At. Spectrom., 16, 26-31, 2001. Copyright 2001 Royal Society of Chemistry. With permission.)... 

Ohtsuka et al. used UTEVA-Resin to set up a Pu analysis method, taking advantage of the ability to retain Pu in the Pu(IV) state, wash away other trivalents, and then selectively reduce and elute the Pu as Pu(III), thus separating it from still-retained U.58 59 Samples were loaded and washed in 3 M HN03, and Pu(III) was released with 0.01 M ascorbic acid in 3 M HN03. Ascorbic acid provides rapid reduction and is destroyed in the ICP-MS torch. A decontamination factor of 6 to 7 orders of magnitude was estimated for the Pu-U separation. After Pu elution, U could be removed in dilute nitric acid. Chemical recovery of Pu was 70% in the analysis of several sediment reference samples. These authors used the PrepLab system set up as shown in Figure 9.18. 

Richer, P., Brandalise, B., Apostolidis, C., Molinet, R., and Mayer, K., Development of a robotized separation method for U-Pu samples using UTEVA resin, in Proc. Int. Workshop on the Application of Extraction Chromatography in Radionuclide Measurements, IRMM, Geel, 9-10 November, 1998. 

UTEVA resin Selective resin U, actinides (IV) Nitric acid, oxalic acid... 

Online separation and preconcentration of thorium and uranium was carried out by means of UTEVA resin. LOV made possible the full automation of the system by the online regeneration of the column. Figure 8.10 shows a scheme of the flow system configuration. 

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