[en] A small-particle (13 μm) styrene-divinylbenzene cation-exchange resin has been used for the separation and determination of trace metals in nuclear materials such as steels, Ni-Cr-Fe alloys, zirconium, and uranium. The eluted metal ions, which included Mn, Fe, Co, Ni, Cu, Zn, and Pb, were monitored with a variable wavelength detector after a post-column reaction with 4-(2-pyridylazo)-resorcinol. The metal ions were determined at 10^-₄ to 1% (w/w) levels by direct injection of solutions of the materials. Interference from uranium, due to the reaction between uranium and the reagent used for detection, was removed either with a masking agent or by a coupled-column technique. 9 figures, 3 tables

[en] This paper reports on hydroxyl radicals that react with halogen substituted phenols by several different ways. One is addition of OH radicals to the aromatic ring, which is followed by elimination of hydrogen halide, H₂O or H^-. The positions of OH radicals attack are dependent on the nature of the halogen which affects the electronic distribution in the ring. The oxidation of fluorophenols, chlorophenols and bromophenols with hydroxyl radicals in N₂O saturated solution has been investigated with pulse radiolysis and γ-irradiation experiments. The intermediates of the reactions were studied by pulse radiolysis. The products created in the γ-irradiation of aqueous solutions of halophenols were analyzed by ion chromatography and high performance liquid chromatography (HPLC). With the combination of time-resolved and steady-state experiments a complete and detailed description of radiolytic oxidation of halophenols by hydroxyl radicals was obtained

[en] The Lewis acid sites present on the underlying zirconium oxide particles are responsible for the unusual elution sequence for amino acids on copper loaded, phosphated zirconium oxide supports reported in an earlier study. To more thoroughly examine the effect of these strong Lewis acid sites in this paper. The authors have studied ligand exchange chromatography on copper loaded zirconium oxide particles. It is shown here that carboxylate functional groups on amino acid solutes strongly interact with surface Lewis acid sites. Addition of competing hard Lewis bases to the eluent attenuates these specific interactions. The result is a chromatographic system with high selectivity which is also suitable for ligand exchange chromatography of proteins

[en] This article indicates the potentials of high performance liquid chromatography (HPLC) as a radiochemical technique for multielement separation of neutron irradiated samples. The focus lies on the convenience to use the detector signal of the eluted components to indicate the chemical yield of the analyte, which has often proved to be a crucial step in radiochemical separations. Two signals have been utilized. The UV signal of the metal-ligand complexes separated by reversed phase HPLC and the radioactive response as a result of sample irradiation of carrier-tracer addition. Change in ratio is discussed between the two signals, if any, for a specific sample. Losses of metal as much as 65% were simulated and corrected using the individual UV response. The method promises improved accuracy for elemental analysis despite losses suffered during the various chemical steps. The procedure omits the necessity of additional analytical steps for yield determination. The present article aims at the chromatographic part of the study. Cobalt as cobalt diethyldithiocarbamate has been used to demonstrate the viability of the concept. The separation was developed on c C18 reverse phase analytical column and optimized on a semi preparative one

[en] A sensitive and specific method for uranium(6) determination using reverse phase ion-pair high performance liquid chromatography with UV detector has been developed. The developed method has been applied for the determination of uranium in a synthetic sample containing most of the interfering ions. Except iron most of the elements and anion which often interfere in uranium assay do not interfere in the present method. Interference of iron is masked by addition of 5mM/1 EDTA solution to the sample

[en] Separation of light lanthanoids with centrifugal partition chromatography (CPC) was investigated in extraction system of 30% HDEHP/CCl₄/n-paraffin and HNO₃. Since separation factors between lanthanoids, Ce, Nd, Pr, Sm, Eu and Gd, were independent of volume ratio of CCl₄ and n-paraffin diluents, difference in the density between the mobile phase and the stationary phase was controlled by varying the volume ratio of two diluents in order to operate at reasonable pump-pressure. The effects of volume of the stationary phase and rotational speed on the separation characteristics of CPC were examined to find the optimum operation conditions. The effect of chain length of n-paraffin (number of carbon atoms: 6--15) as diluents was also examined. The best separation efficiency was obtained with the longest, n-pentadecane. On the basis of the above results, mutual separation of lanthanoids was successfully performed in 30% HDEHP/15% CCl₄/55% n-pentadecane and 0.5 mol/dm³ HNO₃ extraction system at a low pump pressure of 4.5 kgf/cm²

[en] In this paper, a modified method for the separation and determination of Rare Earth Elements in solution is developed. Lanthanide ions were separated by Reversed-Phase Ion Pair Chromatography using a mobile phase gradient of pH and lactic acid concentration. A post-column reaction with 4-(2 pyridyl)azo resorcinol was carried out for the spectrophotometric detection of solutes. The derivatizing reagent composition was optimized for good solute sensitivity and long-term reagent stability. Method limitations due to inadequate instrumentation are presented and discussed

[en] This paper reports on the chromatographic properties of porous microparticulate zirconium oxide surfaces in aqueous media which are highly dependent upon the chemical composition of the eluent. In particular, retention is controlled by the type and concentration of hard Ligand exchange is the dominant mechanism for the retention of solutes which are Lewis bases. consequently, the capacity factor and plate height depend on both the thermodynamic and kinetic properties of whatever competing Lewis bases may be present in the eluent. These Lewis base eluent components act to control retention in two ways. They modify the net ligand exchange contribution to retention, and they serve as sites for secondary interactions, such as hydrogen bonding and hydrophobic interactions between solutes and the dynamic stationary phase