[en] Leachates from a waste degradation experiment, containing ∼700-3700 mg C/I of dissolved organic matter (DOM), were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography (LC), using various separation strategies. Scaling up of the separation scheme to a semi-preparative scale, suitable for hyphenated techniques, was also investigated. Separations with reversed-phase columns suggested that ∼70-93% of the DOM was hydrophilic, and ion-pair chromatography of this fraction showed the presence of several discrete compounds. Labile and non-labile complexes were formed by adding ⁶⁰Co radiotracer. Size-exclusion chromatography indicated that the DOM was primarily in the <1000-1500 Da molecular mass range. (author)

[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] High-performance liquid chromatographic separations (< 20 min) of the lanthanides are illustrated for both 5- and 10-μm bonded-phase strong-acid ion exchangers. The performance of these bonded phase packings is compared with that obtained with a 13-μm styrene-divinylbenzene resin. The eluted metal ions are detected with a variable-wavelength detector after a post-column complexation reaction. The requirements and characteristics of post-column reaction for sensitive metal ion detection after separation on high-performance columns are discussed and the linearity, reproducibility, and sensitivity of the system used in the work are illustrated. The potential of on-column preconcentration for the ultratrace (pg/mL) determination of metal ions is also discussed and illustrated. 7 figures, 2 tables

[en] Ion exchange preconcentration followed by HPLC purification prior to scintillation counting was used to measure the concentration of ¹⁴⁷Pm in urine. the detection limit for this method was found to be 0.1 Bq (3 fg) of ¹⁴⁷Pm in 500 ml of urine

[en] Impurities such as Sm, Gd, Eu, and Dy will degrade the neutron economy of a nuclear reactor when present even at sub-parts-per-million levels, as a result of their high neutron absorption cross sections. Conventional determinations of lanthanide impurities in uranium require 0.5-100 g of uranium. A coupled-column chromatographic procedure has been developed which dramatically reduces the quantity of uranium required. The first column, a semipreparative reversed-phase column, removes the uranium matrix, while the second column, an analytical-scale cation exchange column, concentrates and separates the lanthanides prior to their postcolumn reaction detection with arsenazo III. The maximum loading of uranium onto the reversed-phase column is determined by the volume overload of the lanthanides rather than the concentration overload of the uranium. Using 20 mg of uranium, a detection limit of 0.02 μg/g of U is achieved for Sm, Gd, Eu, and Dy with no interference from transition or alkaline earth metals present in the uranium. 39 refs., 5 figs., 2 tabs

[en] Reversed phases coated with a permanently sorbed ion exchanger and indirect UV detection have been investigated for the determination of simple and multifunctional carboxylic acids in chemical cleaning solutions. The advantages of being able to vary both the ion-exchange capacity and the hydrophobic interactions on these types of ion exchangers for the optimization of resolution and detection are illustrated, and the selection of optimum separation conditions is discussed. Dissolved iron interferes with the analysis due to photochemical, redox, and kinetic effects but good recoveries can be obtained after reduction of the iron with hydroxylamine and complexation with 1,2-diaminocyclohexanetetraacetic acid. Detection limits (3 x base line noise) for oxalate, citrate, ethylenediaminetetraacetate, and hydroxyethylenediaminetriacetate are 0.6-20 μg x mL^-1 for a 20-μL sample, and relative standard deviations are 3 to % in the 75-350 μg x mL^-1 range. Analysis results for reactor decontamination solutions containing up to 250 μg x mL^-1 of iron agree with results obtained by other techniques, and it is shown that this technique should also be useful for determination of metal ions in the samples. A determination of the above reagents in the presence of Fe(II) and Ni(II) takes 7 to 12 min after a 5 to 10 min reduction step. Cr(III) forms nonlabile complexes with ethylenediaminetetraacetic acid, and its presence will cause low results for this acid. 17 references, 4 figures, 6 tables

[en] The experimental factors that contribute to base line noise in the postcolumn-reaction detection of metal ions eluted from high-performance dynamic ion exchangers have been evaluated and compared for a screen-tee reactor (∼ 1 μL internal volume) and three annular membrane reactions having internal volumes of 1.5, 5.3, and 9.6 μL. Measurements of mixing homogeneity, performed with pulseless gas-pressure pumping, showed that both reactor designs gave a mixing homogeneity that was 99.983% of that theoretically possible (perfect mixing) for two solutions differing in absorbance by 2.38 units. For normal operation with high-performance reciprocating pumps for eluent delivery, pump pulsations were responsible for 90-100% of the observed peak-to-peak noise. Column efficiency measurements with a series of lanthanide metal ions gave similar curves for both designs (HETP values of 0.01-0.04 mm). Both reactors gave reproducible peak areas, had good peak shapes, and operated reliably. With the membrane reactors some leakage of eluent into the reagent solution occurred at high eluent or reagent flow rates, but this was not a problem for normal operating conditions

[en] Dynamic ion exchange has been used for the rapid separation (16 min) and determination of rare earths and Y in samples from hydrometallurgical processes used to recover, U, Th, Y, and the rare earths from uranium ore. Optimization of the effective capacity of the dynamic ion exchanger and the selectivity of postcolumn reaction detection permitted analysis down to 0.1 μg-mL^-1 of the rare earths and yttrium in the presence of U, Th, and a number of other metal ions. A comparison with X-ray fluorescence results showed good agreement, and the chromatographic procedure offered considerable savings in analysis time. Studies with Th(IV) and U(VI) showed that both metal ions exhibited selective sorption of their α-hydroxyisobutyric complexes, formed in situ in the eluent, onto reversed phases. The analytical results obtained showed that this dynamic separation process could be used for the determination of Th, and its potential for the determination of U was demonstrated

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