We report spectroscopic studies of laser-induced plasma (LIP) produced by ns-IR-Nd:YAG laser light pulses of different energies onto four different oxides of vanadium (VO, V2O3, VO2, and V2O5) in air under atmospheric pressure. For each oxide with a different oxidation state of vanadium, both electron density and plasma temperature were calculated for different time delays and laser pulse energies. The plasma temperature was determined from Boltzmann plot method, whereas the electron number density was estimated from the Saha equation. The decay rates for plasma temperature as well as electron density were observed to follow power law and were independent of the nature of vanadium oxide. These investigations provide an insight to optimize various parameters during LIBS analysis of vanadium-based matrices.
Thermal ionization mass spectrometry (TIMS) is a widely used method for obtaining information about the isotopic composition of individual isotopes with high resolution and accurate quantification with considerably low detection limits. However, analyses by TIMS require an elaborate sample preparation step to eliminate the matrix and subsequent manual loading of small volumes of purified aqueous samples on a filament surface for thermal ionization. This is cumbersome, particularly for the handling of radioactive solutions. Therefore, in the present work, polymeric material based sorbents were explored for the single step matrix elimination and source preparation for the loading of U(VI) and Pu(IV) ions preconcentrated from a variety of environmental and nuclear fuel reprocessing samples. The solid phase loading offers a number of advantages for handling radioactive materials, and is amenable to matrix elimination and preconcentration of analytes that would further improve the detection limit of TIMS. The polymer based sorbents were prepared by anchoring neutral and acidic phosphate functional groups selective to actinide ions in porous poly(propylene) and poly(ethersulfone) matrices. One of the procedures used for the preparation of polymeric sorbents involved grafting of the monomers phosphoric acid 2-hydroxyethyl methacrylate ester and 2-ethylhexylmethacrylate (EHM) in 1 : 1 molar proportion by UV-initiator induced polymerization in the pores of the host matrix. In another route, the liquid extractants tris(2-ethylhexyl) phosphate (TEHP) along with bis(2-ethylhexyl) phosphoric acid (HDEHP), in different molar proportions, were physically immobilized by capillary force in the pores of poly(propylene) and poly(ethersulfone) membranes and beads. It was observed that the poly(propylene) pyrolyzed easily at a filament temperature close to that used for solution based sample loading, and thus was best suited for the analyses of U(VI) and Pu(IV) by TIMS. The composition of the polymer membrane supported liquid extractant based sorbents was optimized for the preconcentration of U(VI) from ground water and seawater, and also for the preconcentration of Pu(IV) from 3 mol L À1 HNO 3 , which is normally encountered in nuclear fuel reprocessing facilities. The parameters affecting the analytical performance of polymer sorbent based TIMS were evaluated, and tested for the quantification of U and Pu in the ppb concentration range in seawater and urine samples using the isotope dilution method. Sample Pu(IV) conc. (ppm) PolymSorb-TIMS Solution-TIMS Avg. RSD (%) Avg. RSD (%) Dissolver solution 12.90 AE 0.07 0.51 13.05 AE 0.04 0.30This journal is
Single resin bead-based thermal ionization mass spectrometry (TIMS) offers numerous advantages for Pu(iv) determinations in complex aqueous samples.
Gamma spectrometry / Isotope dilution / HPGe / Plutonium / Isotopic composition / ConcentrationSummary. Isotope dilution gamma spectrometry (IDGS) for determination of the Pu concentration, using high resolution gamma-ray spectrometry (HRGS) in the 40-150 keV energy range, is developed and described. The methodology involves purification of Pu by an anion exchange procedure, followed by the determination of Pu isotopic composition using HRGS. For isotope dilution, a precalibrated power reactor grade Pu (∼ 70 at. % 239 Pu) solution from an Indian PHWR was used as a spike for research reactor grade Pu (∼ 95 at. % 239 Pu) samples and vice versa. Changes in 240 Pu/ 239 Pu (45.24 keV/51.62 keV) and 241 Pu/ 239 Pu (148.57 keV/129.29 keV) activity ratios in the spiked samples were determined by gamma spectrometry. Using the atom ratios calculated from the measured activity ratios, the concentration of Pu in the sample was calculated using two different efficiency calibration methods. The isotopic composition and concentration of Pu samples both from power reactor and research reactor grade agreed well with the values obtained by isotope dilution-thermal ionization mass spectrometry. The present method also shows the superiority of using the 240 Pu/ 239 Pu atom ratio against the 241 Pu/ 239 Pu atom ratio in IDGS with respect to the accuracy and precision.
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