Isotopic signature of selected lanthanides for nuclear activities profiling using cloud point extraction and ICP-MS/MS.

The presence of fission products, which include numerous isotopes of lanthanides, can impact the isotopic ratios of these elements in the environment. A cloud point extraction (CPE) method was used as a preconcentration/separation strategy prior to measurement of isotopic ratios of three lanthanides (Nd, Sm, and Eu) by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). To minimise polyatomic interference, the combination of interferents removal by CPE, reaction/collision cell conditions in He and NH3 mode and tandem quadrupole configuration was investigated and provided optimal results for the determination of isotopic ratio in environmental samples. Isotopic ratios were initially measured in San Joaquin soil (NIST-2709a), an area with little contamination of nuclear origin. Finally, samples collected from three sites with known nuclear activities (Fangataufa Lagoon in French Polynesia, Chernobyl and the Ottawa River near Chalk River Laboratory) were analysed and all exhibited altered isotopic ratios for (143/145)Nd, (147/149)Sm, and (151/153)Eu. These results demonstrate the potential of CPE and ICP-MS/MS for the detection of altered isotopic ratio in environmental samples collected in area subjected to nuclear anthropogenic contamination. The detection of variations in these isotopic ratios of fission products represents the first application of CPE in nuclear forensic investigations of environmental samples.

New method for sintering silica frits for capillary microcolumns.

One of the main steps in the manufacture of robust and efficient packed capillary microcolumns for electro- and capillary chromatography is the generation of porous devices to retain the packed beds. Frits based on sintered silica particles have been found to give the best results in terms of mechanical resistance and efficiency. The conventional procedure to produce these kinds of frits consists in a radial heating of the packed material with either a flame or an electrical resistance, but the frits thus obtained have many drawbacks as a result of the procedure rather than the silica per se as the base material. In the present work we investigated a new approach to produce silica-based retaining devices involving the frontal exposure of a short silica-particle bed packed at the end of a capillary tube. The capillary is radially insulated and frontally exposed to the heat of a muffle oven, generating a transfer of heat that is not radial but rather throughout the capillary axis. This procedure resulted in substantial advantages: an improved radial homogeneity, a protection of the external polyimide, and a generation of extremely short (400-600 µm) frits that were highly permeable and avoided bubble formation.

Measurements of association constants between enantiomers and chiral selectors by capillary gas chromatography. Theoretical and practical considerations.

The association constants of several volatile enantiomers with octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin at temperatures between 50 and 100 °C were measured by gas-liquid chromatography using capillary columns coated with different amounts of chiral selector dissolved in polysiloxane OV-1701 and prepared with a precisely determined phase ratio. Simple expressions were deduced to estimate the apparent distribution constants from accurate hold-up and retention times along with that known phase ratio at each temperature. The enantiomer-chiral selector association constants were then calculated from the linear regression of the apparent constants as a function of the chiral selector concentration. One aim of this study consisted in discussing all the experimental uncertainties inherent in the determination of enantiomer/selector association constants with chiral analytes, and how these fundamental measurements can be performed precisely without resorting to the use of reference solutes.

Phosphonate-functionalized large pore 3-D cubic mesoporous (KIT-6) hybrid as highly efficient actinide extracting agent.

A new type of radionuclide extraction material is reported based on phosphonate functionalities covalently anchored on the mesopore surface of 3-D cubic mesoporous silica (KIT-6). The easily prepared nanoporous hybrid shows largely superior performance in selective sorption of uranium and thorium as compared to the U/TEVA commercial resin and 2-D hexagonal SBA-15 equivalent.

Rapid and sensitive gradient liquid chromatography method for the quantitation of ion from neutrophils.

We developed an improved reversed-phase high-performance liquid chromatography (RPLC) assay for the rapid separation and determination of the 2-hydroxyethidium ion. The 2-hydroxyethidium ion is the specific product of the redox reaction between hydroethidine with superoxide radical. High resolution between the chromatographic bands corresponding to ethidium and 2-hydroxyethidium ions was achieved within a practicable analysis time. The RPLC-fluorescence method can reliably detect 2-hydroxyethidium ion concentrations down to 0.12 µM (or 1.2 pmol) and the signal is linear with concentration beyond 50 µM. An application of the method to neutrophil samples demonstrated that intracellular quantification of 2-hydroxyethidium was reproducible, as evidenced by low values of the relative standard deviations: 0.016 for non-stimulated cells, and 0.056 and 0.0125 for neutrophils incubated with agonists phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (fMLP), respectively. The resulting analytical method combines a rapid separation of the relevant peaks with the degree of sensitivity required for use in routine biological analyses.

Permethylated beta-cyclodextrin in liquid poly(oxyethylene) as a stationary phase for capillary gas chromatography.

This paper reports the study of poly(oxyethylene) as a solvent for heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (PM-beta-CD) and the potential of these mixtures for constructing enantioselective gas chromatography columns. Enantioseparations of volatile racemic mixtures using capillaries coated with 10-50% PM-beta-CD diluted in Carbowax 20M were evaluated. The influence of the polymer type on retention, separation and reproducibility over a period of time is critically discussed. The poly(oxyethylene)-based columns were also compared to columns prepared by dilution of PM-beta-CD in two polysiloxanes, SE-30 and SE-54, at several temperatures. Finally, we evaluated a new stationary phase prepared by crosslinking the chiral selector to the poly(oxyethylene) matrix.