Plutonium (IV) Quantification in Technologically Relevant Media Using Potentiometric Sensor Array.

The quantification of plutonium in technological streams during spent nuclear fuel (SNF) reprocessing is an important practical task that has to be solved to ensure the safety of the process. Currently applied methods are tedious, time-consuming and can hardly be implemented in on-line mode. A fast and simple quantitative plutonium (IV) analysis using a potentiometric sensor array based on extracting agents is suggested in this study. The response of the set of specially designed PVC-plasticized membrane sensors can be related to plutonium content in solutions simulating real SNF-reprocessing media through multivariate regression modeling, providing 30% higher precision of plutonium quantification than optical spectroscopy.

N,N,N',N'-Tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide as Very Effective Extraction Agent for Trivalent Europium and Americium.

Solvent extraction of microamounts of Eu3+ and Am3+ from water into nitrobenzene by means of a mixture of hydrogen dicarbollylcobaltate (H+B-) and N,N,N',N'-tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide (L) was studied. The equilibrium data were explained assuming that the species HL+, H2L2+, HL+2, ML3+2, and ML3+3 (M3+ = Eu3+, Am3+; L = N,N,N',N'-tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide) are extracted into the nitrobenzene phase. Extraction and stability constants of the cationic complex species in nitrobenzene saturated with water were determined and discussed. From the experimental results it is evident that this effective N,N,N',N'-tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide receptor for the Eu3+ and Am3+ cations could be considered as a potential extraction agent for nuclear waste treatment.

Synergistic extraction of calcium and strontium into nitrobenzene by using hydrogen dicarbollylcobaltate and n,n´-dimethyl-n,n´-diphenyl-2,6-dipicolinamide.

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of N,N´-dimethyl-N,N´-diphenyl-2,6-dipicolinamide (MePhDPA, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, HL+2, ML2+2 and ML2+3 (M2+ = Ca2+, Sr2+) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in nitrobenzene saturated with water have been determined.

N,N'-Diethyl-N,N'-diphenyl-pyridine-2,6-dicarboxamide.

The asymmetric unit of the title compound, C(23)H(23)N(3)O(2), contains two mol-ecules in both of which, one amide N atom is in a syn position with respect to the pyridine N atom, while the other amide N atom is in an anti position (the syn--anti conformation). There are minor conformational differences between the two mol-ecules, as reflected in the N(pyridine)-C-C-N(amide) torsion angles of -44.9 (3) and 136.0 (2)° for one mol-ecule and 43.5 (3) and -131.1 (2)° for the other mol-ecule. However, the two mol-ecules show significant differences in the orientation of an ethyl group, with corresponding C-C-N-C torsion angles of 86.6 (3)° for one mol-ecule and 79.6 (3)° for the other mol-ecule. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular network.

Predicting the Potentiometric Sensitivity of Membrane Sensors Based on Modified Diphenylphosphoryl Acetamide Ionophores with QSPR Modeling.

While potentiometric, plasticized membrane sensors are known as convenient, portable and inexpensive analytical instruments, their development is time- and resource-consuming, with a poorly predictable outcome. In this study, we investigated the applicability of the QSPR (quantitative structure-property relationship) method for predicting the potentiometric sensitivity of plasticized polymeric membrane sensors, using the ionophore chemical structure as model input. The QSPR model was based on the literature data on sensitivity, from previously studied, structurally similar ionophores, and it has shown reasonably good metrics in relating ionophore structures to their sensitivities towards Cu2+, Cd2+ and Pb2+. The model predictions for four newly synthesized diphenylphosphoryl acetamide ionophores were compared with real potentiometric experimental data for these ionophores, and satisfactory agreement was observed, implying the validity of the proposed approach.

N,N,N',N'-Tetra-isobutyl-pyridine-2,6-dicarboxamide.

In the title compound, C(23)H(39)N(3)O(2), the amide O atoms are displaced by 1.020 (1) and 1.211 (1) Šfrom the mean plane of the central pyridine ring. In the crystal, mol-ecules are connected by weak C-H⋯O hydrogen bonds between methyl-ene groups in the isobutyl substituents and the amide O atoms.

N,N,N',N'-Tetra-ethyl-pyridine-2,6-dicarboxamide.

The title compound, C(15)H(23)N(3)O(2), crystallizes with two mol-ecules in the asymmetric unit which are linked by a C-H⋯N hydrogen bond. In the crystal, mol-ecules are connected via weak C-H⋯O and C-H⋯N hydrogen bonds between the amide O atoms and ethyl chains and between pyridine N atoms and aromatic H atoms in para positions. C-H⋯π inter-actions also occur.

Stability of Different BTBP and BTPhen Extracting or Masking Compounds against γ Radiation.

The radiolytic stability of hydrophobic extracting compounds CyMe4-BTBP and CyMe4-BTPhen and a hydrophilic masking agent (PhSO3H)2-BTPhen, widely employed for trivalent minor actinoid and lanthanoid separation, against γ radiation was tested. Even though the solvent with a promising fluorinated diluent BK-1 provides better extraction properties compared to octan-1-ol, its radiation stability is much lower, and no extraction was observed already after an absorbed dose of 150 kGy (CyMe4-BTBP) or 200 kGy (CyMe4-BTPhen). For the (PhSO3H)2-BTPhen hydrophilic masking agent, the results showed that the rate of radiolytic degradation was significantly higher in 0.25 M HNO3 than in 0.5 M HNO3. For both the hydrophobic and hydrophilic agents, degradation was slower in the presence of both organic and aqueous phases during irradiation.

A combination of dynamic measurement protocol and advanced data treatment to resolve the mixtures of chemically similar analytes with potentiometric multisensor system.

Data processing techniques and measuring protocol are very important parts of the multisensor systems methodology. Complex analytical tasks like resolving the mixtures of two components with very similar chemical properties require special attention. We report on the application of non-linear (artificial neural networks, ANNs) and linear (projections on latent structures, PLS) regression techniques to the data obtained from the flow cell with potentiometric multisensor detection of neighouring lanthanides in the Periodic System of the elements (samarium, europium and gadolinium). Quantification of individual components in mixtures is possible with reasonable precision if dynamic components of the response are incorporated thanks to the use of an automated sequential injection analysis system. The average absolute error in prediction of lanthanides with PLS was around 1 × 10(-4)mol/L, while the use of ANNs allows the lowering of prediction errors down to 2 × 10(-5)mol/L in certain cases. The suggested protocol seems to be useful for other analytical applications where simultaneous determination of chemically similar analytes in mixtures is required.